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Journal articles on the topic 'Microelectrodes'
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1
Xu, Bin, Kang Guo, Likuan Zhu, Xiaoyu Wu, and Jianguo Lei. "Applying Foil Queue Microelectrode with Tapered Structure in Micro-EDM to Eliminate the Step Effect on the 3D Microstructure’s Surface." Micromachines 11, no. 3 (March 24, 2020): 335. http://dx.doi.org/10.3390/mi11030335.
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When using foil queue microelectrodes (FQ-microelectrodes) for micro electrical discharge machining (micro-EDM), the processed results of each foil microelectrode (F-microelectrode) can be stacked to construct three-dimensional (3D) microstructures. However, the surface of the 3D microstructure obtained from this process will have a step effect, which has an adverse effect on the surface quality and shape accuracy of the 3D microstructures. To focus on this problem, this paper proposes to use FQ-microelectrodes with tapered structures for micro-EDM, thereby eliminating the step effect on the 3D microstructure’s surface. By using a low-speed wire EDM machine, a copper foil with thickness of 300 μm was processed to obtain a FQ-microelectrode in which each of the F-microelectrodes has a tapered structure along its thickness direction. These tapered structures could effectively improve the construction precision of the 3D microstructure and effectively eliminate the step effect. In this paper, the effects of the taper angle and the number of microelectrodes on the step effect were investigated. The experimental results show that the step effect on the 3D microstructure’s surface became less evident with the taper angle and the number of F-microelectrodes increased. Finally, under the processing voltage of 120 V, pulse width of 1 μs and pulse interval of 10 μs, a FQ-microelectrode (including 40 F-microelectrodes) with 10° taper angle was used for micro-EDM. The obtained 3D microstructure has good surface quality and the step effect was essentially eliminated.
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Liu, Hong, Xun Liu, and Ning Ding. "An Innovative in Situ Monitoring of Sulfate Reduction within a Wastewater Biofilm by H2S and SO42− Microsensors." International Journal of Environmental Research and Public Health 17, no. 6 (March 19, 2020): 2023. http://dx.doi.org/10.3390/ijerph17062023.
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Microelectrodes can be used to obtain chemical profiles within biofilm microenvironments. For example, sulfate (SO42−) and hydrogen sulfide (H2S) microelectrodes can be used to study sulfate reduction activity in this context. However, there is no SO42− microelectrode available for studying sulfate reduction in biofilms. In this study, SO42− and H2S microelectrodes were fabricated and applied in the measurement of a wastewater membrane-aerated biofilm (MAB) to investigate the in situ sulfate reduction activity. Both the SO42− and H2S microelectrodes with a tip diameter of around 20 micrometers were successfully developed and displayed satisfying selectivity to SO42− and H2S, respectively. The Nernstian slopes of calibration curves of the fabricated SO42− electrodes were close to −28.1 mV/decade, and the R2 values were greater than 98%. Within the selected concentration range from 10−5 M (0.96 mg/L) to 10−2 M (960 mg/L), the response of the SO42− microelectrode was log-linearly related to its concentration. The successfully fabricated SO42− microelectrode was combined with the existing H2S microelectrode and applied on an environmental wastewater biofilm sample to investigate the sulfate reduction activity within it. The H2S and SO42− microelectrodes showed stable responses and good performance, and the decrease of SO42− with an accompanying increased of H2S within the biofilm indicated the in situ sulfate reduction activity. The application of combined SO42− and H2S microelectrodes in wastewater biofilms could amend the current understanding of sulfate reduction and sulfur oxidation within environmental biofilms based on only H2S microelectrodes.
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Zhu, Zheng Han, Jing Quan Liu, Yue Feng Rui, and Chun Sheng Yang. "A Research on Implantable Microelectrodes for EMG Signal Acquisition." Key Engineering Materials 483 (June 2011): 387–91. http://dx.doi.org/10.4028/www.scientific.net/kem.483.387.
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Signal acquisition microelectrode works as an interface between tissue and circuit in neural engineering. Stable, precise and lossless detection of EMG is important to functional neuromuscular stimulation. In this paper, we propose an implantable microelectrode for EMG acquisition fabricated by MEMS technology and test the impedance of several microelectrodes fabricated with different parameters. By analyzing the amplitudes and power spectrum of the EMG signals acquired from rabbits by fabricated microelectrodes, the signal acquisition performances of the microelectrodes are evaluated and compared both in time domain and frequency domain.
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Erofeev, Alexander, Ivan Antifeev, Anastasia Bolshakova, Ilya Bezprozvanny, and Olga Vlasova. "In Vivo Penetrating Microelectrodes for Brain Electrophysiology." Sensors 22, no. 23 (November 23, 2022): 9085. http://dx.doi.org/10.3390/s22239085.
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In recent decades, microelectrodes have been widely used in neuroscience to understand the mechanisms behind brain functions, as well as the relationship between neural activity and behavior, perception and cognition. However, the recording of neuronal activity over a long period of time is limited for various reasons. In this review, we briefly consider the types of penetrating chronic microelectrodes, as well as the conductive and insulating materials for microelectrode manufacturing. Additionally, we consider the effects of penetrating microelectrode implantation on brain tissue. In conclusion, we review recent advances in the field of in vivo microelectrodes.
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Cheng, E., Ben Xing, Shanshan Li, Chengzhuang Yu, Junwei Li, Chunyang Wei, and Cheng Cheng. "Pressure-Driven Micro-Casting for Electrode Fabrication and Its Applications in Wear Grain Detections." Materials 12, no. 22 (November 10, 2019): 3710. http://dx.doi.org/10.3390/ma12223710.
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The microelectrode is an essential and vital part in microsensors that are largely used in industrial, chemical, and biological applications. To obtain desired microelectrodes in great quality, it is also of great necessity and significance to develop a robust method to fabricate the microelectrode pattern. This work developed a four-terminal differential microelectrode that aims at recognizing microparticles in fluids. This microelectrode pair consisted of a high height–width ratio microelectrode array fabricated using a pre-designed microelectrode pattern (a micro-scale channel) and melted liquid metal. The surface treatment of microelectrodes was also investigated to reveal its impacts on the continuality of melting metal and the quality of the fabricated microelectrode patterns. To evaluate the performance of micro-casting fabricated electrodes, a microfluidic device was packaged using a microelectrode layer and a flow layer. Then impedance cytometer experiments were performed using sample fluids with polymer particles in two different sizes in diameter (5 μm and 10 μm). In addition, engine oil was tested on the microelectrodes as complex samples. The number of abrasive particles in the engine oil can be collected from the developed microfluidic device for further analysis.
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Buyong, M. R., J. Yunas, A. A. Hamzah, B. Yeop Majlis, F. Larki, and N. Abd Aziz. "Design, fabrication and characterization of dielectrophoretic microelectrode array for particle capture." Microelectronics International 32, no. 2 (May 5, 2015): 96–102. http://dx.doi.org/10.1108/mi-10-2014-0041.
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Purpose – The purpose of this study is to design and characterize the dielectrophoretic (DEP) microelectrodes with various array structure arrangements in order to produce optimum non-uniform electric field for particle capture. The DEP-electrodes with 2D electrode structure was fabricated and characterized to see the effect of electrode structure configuration on the capture capability of the cells suspending in the solution. Design/methodology/approach – The presented microelectrode array structures are made of planar conductive metal structure having same size and geometry. Dielectrophoretic force (FDEP) generated in the fluidic medium is initially simulated using COMSOL Multi-physics performed on two microelectrodes poles, which is then continued on three-pole microelectrodes. The proposed design is fabricated using standard MEMS fabrication process. Furthermore, the effect of different sinusoidal signals of 5, 10 and 15 volt peak to peak voltage (Vpp) at fixed frequency of 1.5 MHz on capturing efficiency of microelectrodes were also investigated using graphite metalloids particles as the suspended particles in the medium. The graphite particles that are captured at the microelectrode edges are characterized over a given time period. Findings – Based on analysis, the capturing efficiency of microelectrodes at the microelectrode edges is increased as voltage input increases, confirming its dependency to the FDEP strength and direction of non-uniform electric field. This dependency to field consequently increases the surface area of the accumulated graphite. It is also showed that the minimum ratio of the surface accumulated area of captured graphite is 1, 2.75 and 9 μm2 for 5, 10 and 15 Vpp, respectively. The simulation result also indicates a significant improvement on the performance of microelectrodes by implementing third pole in the design. The third pole effect the particles in the medium by creating stronger non-uniform electric field as well as more selective force toward the microelectrodes’ edges. Originality/value – The microelectrode array arrangement is found as a reliable method to increase the strength and selectivity of non-uniform electric field distribution that affect FDEP. The presented findings are verified through experimental test and simulation results.
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Lei, Jianguo, Kai Jiang, Xiaoyu Wu, Hang Zhao, and Bin Xu. "Surface Quality Improvement of 3D Microstructures Fabricated by Micro-EDM with a Composite 3D Microelectrode." Micromachines 11, no. 9 (September 19, 2020): 868. http://dx.doi.org/10.3390/mi11090868.
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Three-dimensional (3D) microelectrodes used for processing 3D microstructures in micro-electrical discharge machining (micro-EDM) can be readily prepared by laminated object manufacturing (LOM). However, the microelectrode surface always appears with steps due to the theoretical error of LOM, significantly reducing the surface quality of 3D microstructures machined by micro-EDM with the microelectrode. To address the problem above, this paper proposes a filling method to fabricate a composite 3D microelectrode and applies it in micro-EDM for processing 3D microstructures without steps. The effect of bonding temperature and Sn film thickness on the steps is investigated in detail. Meanwhile, the distribution of Cu and Sn elements in the matrix and the steps is analyzed by the energy dispersive X-ray spectrometer. Experimental results show that when the Sn layer thickness on the interface is 8 μm, 15 h after heat preservation under 950 °C, the composite 3D microelectrodes without the steps on the surface were successfully fabricated, while Sn and Cu elements were evenly distributed in the microelectrodes. Finally, the composite 3D microelectrodes were applied in micro-EDM. Furthermore, 3D microstructures without steps on the surface were obtained. This study verifies the feasibility of machining 3D microstructures without steps by micro-EDM with a composite 3D microelectrode fabricated via the proposed method.
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Castagnola, Elisa, Nasim Winchester Vahidi, Surabhi Nimbalkar, Srihita Rudraraju, Marvin Thielk, Elena Zucchini, Claudia Cea, et al. "In Vivo Dopamine Detection and Single Unit Recordings Using Intracortical Glassy Carbon Microelectrode Arrays." MRS Advances 3, no. 29 (2018): 1629–34. http://dx.doi.org/10.1557/adv.2018.98.
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ABSTRACTIn this study, we present a 4-channel intracortical glassy carbon (GC) microelectrode array on a flexible substrate for the simultaneous in vivo neural activity recording and dopamine (DA) concentration measurement at four different brain locations (220µm vertical spacing). The ability of GC microelectrodes to detect DA was firstly assessed in vitro in phosphate-buffered saline solution and then validated in vivo measuring spontaneous DA concentration in the Striatum of European Starling songbird through fast scan cyclic voltammetry(FSCV). The capability of GC microelectrode arrays and commercial penetrating metal microelectrode arrays to record neural activity from the Caudomedial Neostriatum of European starling songbird was compared. Preliminary results demonstrated the ability of GC microelectrodes in detecting neurotransmitters release and recording neural activity in vivo. GC microelectrodes array may, therefore, offer a new opportunity to understand the intimate relations linking electrophysiological parameters with neurotransmitters release.
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Stulík, Karel, Christian Amatore, Karel Holub, Vladimír Marecek, and Wlodzimierz Kutner. "Microelectrodes. Definitions, characterization, and applications (Technical report)." Pure and Applied Chemistry 72, no. 8 (January 1, 2000): 1483–92. http://dx.doi.org/10.1351/pac200072081483.
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Theory, preparation,and applications of microelectrodes and microelectrode arrays are critically reviewed, and future trends in the field are outlined. An operational definition of a microelectrode is also recommended.
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Mooney, J. L., V. Lyall, M. Acevedo, and W. M. Armstrong. "Double-barreled K+-selective microelectrodes based on dibenzo-18-crown-6." American Journal of Physiology-Cell Physiology 255, no. 3 (September 1, 1988): C408—C412. http://dx.doi.org/10.1152/ajpcell.1988.255.3.c408.
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Liquid ion-exchanger microelectrodes based on Corning code 477317 K+ exchanger are known to be much more sensitive to quaternary ammonium ions than to K+. In the presence of such cations, the capability of measuring K+ activities with Corning microelectrodes may be seriously impaired. We have developed a neutral carrier K+-selective microelectrode based on the crown ether dibenzo-18-crown-6. The crown ether cocktail contained (wt/wt) 2.3% dibenzo-18-crown-6, 0.8% Na-tetraphenylborate, 30.1% 2-nitrophenylocylether, and 66.8% O-nitrotoluene. Double-barreled crown ether and Corning microelectrodes were calibrated in KCl solutions with or without choline, acetylcholine, tetramethylammonium, imidazole, Na+, tris(hydroxymethyl)aminomethane (Tris), and N-methyl-D-glucamine. Both kinds of microelectrodes showed similar K+ over Na+, Tris, and N-methyl-D-glucamine selectivities. However, crown ether microelectrodes had immensely greater selectivities of K+ over quaternary ammonium ions and imidazole than Corning microelectrodes. Selectivity factors, defined as log K(ij)K, of crown ether microelectrodes with respect to K+ for tetramethylammonium, choline, acetylcholine, and imidazole were -1.92 +/- 0.13, -2.97 +/- 0.03, -1.75 +/- 0.15, and -1.30 +/- 0.20, respectively. Intracellular K+ activities measured in the same Necturus gallbladders with both kinds of microelectrodes did not differ significantly.
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Chang, An-Yi, Shabnam Siddiqui, and Prabhu U. Arumugam. "Nafion and Multiwall Carbon Nanotube Modified Ultrananocrystalline Diamond Microelectrodes for Detection of Dopamine and Serotonin." Micromachines 12, no. 5 (May 6, 2021): 523. http://dx.doi.org/10.3390/mi12050523.
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Neurochemicals play a critical role in the function of the human brain in healthy and diseased states. Here, we have investigated three types of microelectrodes, namely boron-doped ultrananocrystalline diamond (BDUNCD), nafion-modified BDUNCD, and nafion–multi-walled carbon nanotube (MWCNT)-modified BDUNCD microelectrodes for long-term neurochemical detection. A ~50 nm-thick nafion–200-nm-thick MWCNT-modified BDUNCD microelectrode provided an excellent combination of sensitivity and selectivity for the detection of dopamine (DA; 6.75 μA μM−1 cm−2) and serotonin (5-HT; 4.55 μA μM−1 cm−2) in the presence of excess amounts of ascorbic acid (AA), the most common interferent. Surface stability studies employing droplet-based microfluidics demonstrate rapid response time (<2 s) and low limits of detection (5.4 ± 0.40 nM). Furthermore, we observed distinguishable DA and 5-HT current peaks in a ternary mixture during long-term stability studies (up to 9 h) with nafion–MWCNT-modified BDUNCD microelectrodes. Reduced fouling on the modified BDUNCD microelectrode surface offers significant advantages for their use in long-term neurochemical detection as compared to those of prior-art microelectrodes.
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Zhang, Xiao-Ling, Zhong Yang, Xiao-Ping Wan, Ning Hu, Xiao-Lin Zheng, and Jun Yang. "SOI SUBSTRATE-BASED MICROFLUIDIC CHIP FOR CELL ELECTROFUSION." Biomedical Engineering: Applications, Basis and Communications 26, no. 02 (March 12, 2014): 1450019. http://dx.doi.org/10.4015/s1016237214500197.
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A microelectrode array-based cell electrofusion chip was fabricated by using the MEMS technique. Because of the short distance between two counter microelectrodes, the working voltage on this chip was only 1/100–1/20 as that in the traditional cell electrofusion method. Simulation method was used to analyze the on-chip electric field distribution and optimize the structure of the microelectrodes. The results showed the length and width of the microelectrode, and the distance between two microelectrodes in the horizontal and vertical direction would impact the strength and distribution of the electric field. Thus, optimized chip architecture was obtained, on which six individual chambers were integrated. At least 1680 microelectrodes were patterned within any one chamber. Alternating current signals have been used to manipulate and align cells, and most cells were aligned as cell–cell twins. High-intensity (~103 V/cm) electric pulses were used to fuse the aligned cell–cell twins. The fusion efficiency was about 40%, which was much higher than that in traditional chemical method (less than 1‰) and electrofusion methods (less than 5%).
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Miura, Kohichi, Shun Ichiro Kohmo, Takazo Yamada, and Hwa Soo Lee. "Generation of Microelectrodes for Micro EDM." Key Engineering Materials 581 (October 2013): 310–15. http://dx.doi.org/10.4028/www.scientific.net/kem.581.310.
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In order to fabricate micro holes by EDM process, microelectrodes with high accuracy of form are needed. At present, micro electrodes are generated by grinding and/or on-machine EDM operations and then it is well known that efficient productivity of micro electrodes cannot be realized. Controlling method of thrust force for micro shaft is already proposed. Applying this method, thrust force is controlled to be 0 in turning operation, therefore microelectrodes are generated efficiently. Actually, microelectrode which diameter is less than 0.1 mm can be easily machined in short time. high-precision micro hole machining requires microelectrodes with high cylindricity. In this study, turning method for microelectrodes with high cylindricity is discussed.
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Kim, Jonghun, and Sang-Hee Yoon. "Failure Mechanisms of a Gold Microelectrode in Bioelectronics Applications." Journal of Nanomaterials 2015 (2015): 1–7. http://dx.doi.org/10.1155/2015/792198.
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The generation, growth, and collapse of tiny bubbles are inevitable for a microelectrode working in aqueous environment, thus resulting in physical damages on the microelectrode. The failure mechanisms of a microelectrode induced by tiny bubble collapsing are investigated by generating tiny hydrogen bubbles on a gold microelectrode through deionized water electrolysis. The surface of the microelectrode is modified with a thiol-functionalized arginine-glycine-aspartic acid peptide to generate perfectly spherical bubbles in proximity of the surface. The failure of an Au microelectrode is governed by two damage mechanisms, depending on the thickness of the microelectrode: a water-hammer pressure due to the violent collapse of a single large bubble, formed through merging of small bubbles, for ultrathin Au microelectrodes of 40–60 nm in thickness, and an energy accumulation resulting from the repetitive collapse of tiny bubbles for thick Au microelectrodes of 100–120 nm.
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Kuwana, Yoshihiko. "Epoxy-Based Multichannel Microelectrode for Insect Biopotential Recording." Journal of Robotics and Mechatronics 18, no. 4 (August 20, 2006): 499–503. http://dx.doi.org/10.20965/jrm.2006.p0499.
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Microelectrodes are being developed in order to record action biopotentials of insects. Silicon was conventionally used as the electrode material and microelectrodes were fabricated by anisotropic etching and reactive ion etching. Because electrode microprobe shape and size were very difficult to control, we propose a novel pin-shaped multichannel microelectrode. Epoxy-based UV photoresist must be used as the electrode material to facilitate the control of the microelectrode shape and size. Analysis of the electrical properties of this electrode showed that it has properties excellent enough to record insect biopotentials.
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Cisnal, Ana, Frank R. R. Ihmig, Juan-Carlos Fraile, Javier Pérez-Turiel, and Víctor Muñoz-Martinez. "Application of a Novel Measurement Setup for Characterization of Graphene Microelectrodes and a Comparative Study of Variables Influencing Charge Injection Limits of Implantable Microelectrodes." Sensors 19, no. 12 (June 17, 2019): 2725. http://dx.doi.org/10.3390/s19122725.
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Depending on their use, electrodes must have a certain size and design so as not to compromise their electrical characteristics. It is fundamental to be aware of all dependences on external factors that vary the electrochemical characteristics of the electrodes. When using implantable electrodes, the maximum charge injection capacity (CIC) is the total amount of charge that can be injected into the tissue in a reversible way. It is fundamental to know the relations between the characteristics of the microelectrode itself and its maximum CIC in order to develop microelectrodes that will be used in biomedical applications. CIC is a very complex measure that depends on many factors: material, size (geometric and effectiveness area), and shape of the implantable microelectrode and long-term behavior, composition, and temperature of the electrolyte. In this paper, our previously proposed measurement setup and automated calculation method are used to characterize a graphene microelectrode and to measure the behavior of a set of microelectrodes that have been developed in the Fraunhofer Institute for Biomedical Engineering (IBMT) labs. We provide an electrochemical evaluation of CIC for these microelectrodes by examining the role of the following variables: pulse width of the stimulation signal, electrode geometry and size, roughness factor, solution, and long-term behavior. We hope the results presented in this paper will be useful for future studies and for the manufacture of advanced implantable microelectrodes.
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Heim, Matthias, Lionel Rousseau, Stéphane Reculusa, Veronika Urbanova, Claire Mazzocco, Sébastien Joucla, Laurent Bouffier, et al. "Combined macro-/mesoporous microelectrode arrays for low-noise extracellular recording of neural networks." Journal of Neurophysiology 108, no. 6 (September 15, 2012): 1793–803. http://dx.doi.org/10.1152/jn.00711.2011.
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Microelectrode arrays (MEAs) are appealing tools to probe large neural ensembles and build neural prostheses. Microelectronics microfabrication technologies now allow building high-density MEAs containing several hundreds of microelectrodes. However, several major problems become limiting factors when the size of the microelectrodes decreases. In particular, regarding recording of neural activity, the intrinsic noise level of a microelectrode dramatically increases when the size becomes small (typically below 20-μm diameter). Here, we propose to overcome this limitation using a template-based, single-scale meso- or two-scale macro-/mesoporous modification of the microelectrodes, combining the advantages of an overall small geometric surface and an active surface increased by several orders of magnitude. For this purpose, standard platinum MEAs were covered with a highly porous platinum overlayer obtained by lyotropic liquid crystal templating possibly in combination with a microsphere templating approach. These porous coatings were mechanically more robust than Pt-black coating and avoid potential toxicity issues. They had a highly increased active surface, resulting in a noise level ∼3 times smaller than that of conventional flat electrodes. This approach can thus be used to build highly dense arrays of small-size microelectrodes for sensitive neural signal detection.
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Biswas, Shatavisha, Arkaprava Datta, and Tarun Kanti Bhattacharyya. "(Digital Presentation) Fabrication and Characterization of C-MEMS Based 3-Dimensional Microelectrode Arrays for Cardiac Electrophysiological Studies." ECS Meeting Abstracts MA2022-01, no. 53 (July 7, 2022): 2218. http://dx.doi.org/10.1149/ma2022-01532218mtgabs.
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In-vitro examination of the electrical conduction characteristics and the beating of cardiomyocytes can be done using Microelectrode arrays(MEAs). The microelectrodes continuously monitor the electrical activity of the active cardiac cells on a microsecond timescale and presents a precise data based on that. Since the introduction of MEAs, many efforts have been made by scientists to evolve this technology by means of microfabrication. Previously, planar metallic electrodes were mostly used for this study but they could not penetrate the dead cells and reach the active cell layers. To overcome this, protruding 3-D microelectrodes were introduced that could puncture the dead tissues and reach the active cells for effective recording of cardiac electrical potentials. The characteristics of an electrode are defined by the characteristics of the material used to develop it. In this paper, we focus on the fabrication of cylindrical 3-dimensional Glassy Carbon microelectrode arrays (MEAs) for analyzing cell preparations from cardiac tissues. In order to improve the electrical properties of the commercially available electrodes, we have used a highly conductive material for fabrication. Glassy Carbon microelectrodes were fabricated by the pyrolysis of SU-8 microelectrodes which were developed by a standard lithographic process on Silicon wafer. The ohmic nature and high conductivity of Glassy Carbon makes it a suitable material to be implemented in electrophysiological studies. Further in our work, we have performed the theoretical and structural analysis using Comsol Multiphysics 5.2 considering different geometries of microelectrodes. The skin insertion force is calculated to be 0.012N, which is much lesser than the comprehensive force (15.38N), the maximum bending force (0.885N) and the maximum buckling force (3.28N) per cylindrical microelectrode. The maximum Von Mises stress (as shown in the figure) acting at the base where it is attached to the substrate is found out to be 6.56x106 N/m2 for each cylindrical microneedle. Among all the considered geometries, it can be concluded that the fabricated cylindrical microelectrodes penetrate successfully without breaking or bending and causing minimal damage to the cardiac tissues. The slanted tip microelectrode was also favored as it’s design makes it able to easily pierce the cardiac cell layers. However, the Maximum Von Mises stress distribution showed that the stress at the tip was much higher than the Yield strength of Glassy Carbon (4Gpa) making it evident that the tip might break while penetrating. With the theoretical and simulation analysis performed we were thus able to optimize the geometry and establish that Glassy Carbon proves to be a good material for fabrication of 3D microelectrode arrays. Figure 1
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Jodeiri Iran, Keyvan, Aleksandra Foerster, Jisun Im, and Christopher Tuck. "Surface Functionalisation and Electroless Plating of 3D-Printed Microstructures." ECS Meeting Abstracts MA2022-01, no. 57 (July 7, 2022): 2372. http://dx.doi.org/10.1149/ma2022-01572372mtgabs.
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A microelectrode with a large surface area is one of the essential components in biosensors, electronic implants, and energy harvesting systems. In particular, enzymatic biofuel cells and biosensors benefit significantly from microelectrodes with a large surface area to volume ratio because of the increased enzyme loading and hence improved the power density of the final devices. Therefore, the fabrication of microelectrodes with a large surface area will advance its application in devices. Projection-microstereolitography (PµSLA) offers the ability to fabricate three-dimensional and geometrically adjustable polymeric microstructures with well-defined complex shapes in microscale. 3D polymeric microstructures produced using PµSLA can be then coated with metal to achieve high conductivity. Microelectrodes have been created via 3D printing of polymeric structures followed by electroless plating. However, the weak adhesion of the metal to the polymer limits the practical use of the produced devices as electrodes. Here, we show the method to introduce thiol groups on the surface of PµSLA-generated polymeric microstructures to improve the adhesion between the polymer surface and gold thin film. Our results demonstrate that thiol groups on the polymer surface provide the anchoring site for gold deposition during electroless plating via gold-sulfur bonding, resulting in strong adhesion between the polymer surface and the gold layer and long-term microelectrode durability. The gold coated 3D microelectrode exhibits excellent electrical conductivity up to 1.4 × 107 S/m (35% of bulk gold). This method can offer exciting potential for constructing microelectrodes for architecture-specific applications in future energy, catalysis, and sensing.
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Mauzeroll, Janine. "The Good, the Bad and the Ugly of pH Microelectrodes." ECS Meeting Abstracts MA2023-01, no. 52 (August 28, 2023): 2629. http://dx.doi.org/10.1149/ma2023-01522629mtgabs.
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pH micro electrodes have been around for many years with several architectures already reported. We will review the existing options critically providing guidance on their fabrication, advantages and limitations. We will also report a new fabrication method to produce Pd hydride pH microelectrode using a chemical approach to synthesize the Pd hydride. In contrast to electrochemically generated PdH microelectrodes, this chemically generated Pd hydride microelectrodes are longer lasting, allowing long-time localized pH measurements.
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Gong, Jiahao, Bingxin Liu, Pan Zhang, Huimin Zhang, and Lin Gui. "Copper-Electroplating-Modified Liquid Metal Microfluidic Electrodes." Sensors 22, no. 5 (February 25, 2022): 1820. http://dx.doi.org/10.3390/s22051820.
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Here, we report a novel technology for the fabrication of copper-electroplating-modified liquid metal microelectrodes. This technology overcomes the complexity of the traditional fabrication of sidewall solid metal electrodes and successfully fabricates a pair of tiny stable solid-contact microelectrodes on both sidewalls of a microchannel. Meanwhile, this technology also addresses the instability of liquid metal electrodes when directly contacted with sample solutions. The fabrication of this microelectrode depends on controllable microelectroplating of copper onto the gallium electrode by designing a microelectrolyte cell in a microfluidic chip. Using this technology, we successfully fabricate various microelectrodes with different microspacings (from 10 μm to 40 μm), which were effectively used for capacitive sensing, including droplet detection and oil particle counting.
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Kojabad, Zohreh Deljoo, Sohrab Sanjabi, and Seyed Abbas Shojaosadati. "Electrodeposition of Gold and Polypyrrole Thin Films for Neural Microelectrodes." Advanced Materials Research 829 (November 2013): 337–41. http://dx.doi.org/10.4028/www.scientific.net/amr.829.337.
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A low impedance electrode/tissue interface is critically important for neural microelectrodes recording to maintain signal quality. In this study, gold/polypyrrol thin films used to decrease the interface impedance. Gold thin film was electrodeposited by cyclic voltammetry in the potential range of-0.3 to 1 volt on the stainless steel surface of microelectrodes with 127 micrometer in radius. Then polypyrrole was electrodeposited on the gold layer. Electrochemical impedance spectroscopy tests were performed for impedance measurement of microelectrode surface. The effect of morphology and thickness on the impedance of thin film was studied. The results showed that the impedance of the microelectrodes with gold/polypyrrol coatings was 38.2% lower than the electrodes without coating in the neural frequency.
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Ammann, Daniel, Urs Oesch, Thomas Bührer, and Wilhelm Simon. "Design of ionophores for ion-selective microsensors." Canadian Journal of Physiology and Pharmacology 65, no. 5 (May 1, 1987): 879–84. http://dx.doi.org/10.1139/y87-141.
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Requirements for a reliable use of liquid membrane microelectrodes are discussed in terms of stability, response time, and lifetime on the basis of membrane technological considerations. The selectivity of H+, Li+, Na+, K+, Mg2+, Ca2+, and Cl− microelectrodes is critically evaluated using the Nikolskii-Eisenman formalism. Recent progress in the design of new ionophores is presented. A novel neutral carrier-based Ca2+-selective microelectrode with a detection limit of about 5 × 10−10 M Ca2+ at a background of 125 mM K+ has been realized. An neutral carrier-based microelectrode for H+ with extended pH range of the sample solution is now available. Promising developments in the field of Li+-, Mg2+-, and Cl−-selective ionophores are discussed.
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Maddah, Mohsen, Charles P. Unsworth, Gideon J. Gouws, and Natalie O. V. Plank. "Synthesis of encapsulated ZnO nanowires provide low impedance alternatives for microelectrodes." PLOS ONE 17, no. 6 (June 16, 2022): e0270164. http://dx.doi.org/10.1371/journal.pone.0270164.
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Microelectrodes are commonly used in electrochemical analysis and biological sensing applications owing to their miniaturised dimensions. It is often desirable to improve the performance of microelectrodes by reducing their electrochemical impedance for increasing the signal-to-noise of the recorded signals. One successful route is to incorporate nanomaterials directly onto microelectrodes; however, it is essential that these fabrication routes are simple and repeatable. In this article, we demonstrate how to synthesise metal encapsulated ZnO nanowires (Cr/Au-ZnO NWs, Ti-ZnO NWs and Pt-ZnO NWs) to reduce the impedance of the microelectrodes. Electrochemical impedance modelling and characterisation of Cr/Au-ZnO NWs, Ti-ZnO NWs and Pt-ZnO NWs are carried out in conjunction with controls of planar Cr/Au and pristine ZnO NWs. It was found that the ZnO NW microelectrodes that were encapsulated with a 10 nm thin layer of Ti or Pt demonstrated the lowest electrochemical impedance of 400 ± 25 kΩ at 1 kHz. The Ti and Pt encapsulated ZnO NWs have the potential to offer an alternative microelectrode modality that could be attractive to electrochemical and biological sensing applications.
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Khazanna, S. Fitriyani, R. Safitri, K. Lahna, E. Yusibani, Irwansyah, and E. Iswardy. "Dielectrophoretic force characteristics toward Lactobacillus casei on an oblique-patterned electrode." Journal of Physics: Conference Series 2734, no. 1 (March 1, 2024): 012004. http://dx.doi.org/10.1088/1742-6596/2734/1/012004.
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Abstract Dielectrophoresis-based biochips with various microelectrode configurations have been extensively studied within the last five deca des. However, wide-field application is still challenging. This study aims to fabricate an oblique-configuration microelectrode and then utilizes it to determine the dielectrophoretic (DEP) characteristics of Lactobacillus casei based on the generated non-uniform electric field. The electric field distribution on microelectrodes was simulated with Quickfield 6.6 student version. The microelectrodes were fabricated using a copper film on a glass substrate. The DEP characteristic of Lactobacillus casei was investigated by applying a sinusoidal AC signal to microelectrodes in medium solution with an electrical conductivity of 0.05 S/m. The electric-field simulations show that the strongest electric-field was generated on the tip of electrodes spacing, and the weakest electric-field was generated on the inner of electrodes spacing. The negative-DEP force on Lactobacillus casei was observed at the frequency of 60–130 kHz, while the positive-DEP force was observed at the frequency of 380–700 kHz, both at voltage of 2–6 Vpp. The nDEP force led Lactobacillus casei to be pushed toward the weak electric field on the inner of electrodes spacing, and the pDEP force induced Lactobacillus casei to be attracted toward the strong electric-field on the tip of electrodes spacing. This study implies that the proposed oblique-microelectrode platform has promising application for bioparticles separation.
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Oesch, Urs, Daniel Ammann, and Wilhelm Simon. "Cell contamination due to the use of carrier-based microelectrodes." Canadian Journal of Physiology and Pharmacology 65, no. 5 (May 1, 1987): 885–88. http://dx.doi.org/10.1139/y87-142.
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When using microelectrodes for intracellular ion activity studies, some uncertainties such as interference from cytosolic components at the microelectrode, cell damage, and cell contamination may arise. A model, which treats kinetic processes of the loss of carriers from the membrane phase of microelectrodes into the cytosol and cell membrane, is used for an estimation of the extent and time course of contamination by impaled ion-selective microelectrodes. An isolated model cell consisting of a plasma membrane surrounding a cytosolic milieu is assumed. The results of its considerations represent a worst case situation, in which significant contamination of the cell membrane of such a small isolated single cell might occur during time periods of electrophysiological experiments. In more complex situations, such as in intact tissues, the equilibrium membrane concentrations may be substantially less.
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Zazueta-Gambino, Alvaro, Claudia Reyes-Betanzo, and José Herrera-Celis. "Design of a Biosensor Based on Interdigitated Microelectrodes with Detection Zone Controlled by an Integrated Microfluidic Channel." Journal of Integrated Circuits and Systems 15, no. 2 (July 31, 2020): 1–5. http://dx.doi.org/10.29292/jics.v15i2.167.
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The design and simulation of a biosensor based on interdigitated microelectrodes for bacteria detection is presented. The biosensor includes a microchannel to ensure the flow of the sample through the space between microelectrodes, where the surface is biofunctionalized with antibodies to capture the bacteria. The design was built on COMSOL Multiphysics® software. The effects of the microelectrode thickness and the channel depth on the biosensor sensitivity were studied by simulation. There is a specific microelectrode thickness at which the sensitivity is maximum for Escherichia coli. The microchannel depth affects the sensitivity of the device when it is below 10 μm, approximately. The sensitivity increases when the biosensor is made with low-permittivity materials. A maximum percentage change in capacitance of around 46% was obtained by covering the total sensing area with bacteria.
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Li, Yuanjiao, Janine Mauzeroll, and Samuel Charles Perry. "Fabrication of a Palladium Hydride pH Microelectrode with an Extended Lifetime." ECS Meeting Abstracts MA2023-02, no. 62 (December 22, 2023): 2931. http://dx.doi.org/10.1149/ma2023-02622931mtgabs.
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Stable miniaturized pH microelectrodes are crucial in exploring localized pH changes, but most suffer from instability and short lifetimes. Palladium hydride in a mixer phase has been reported to measure the solution pH taking advantage of the interaction between the alloyed hydrogen atoms and hydrogen ions in the solution. However, with the escape of the hydrogen atoms from the palladium lattice, the palladium hydride will transition to single phase and become invalid for pH measurement. The duration of the mixer-phase palladium hydride is even shorter as the sensor is made small. A method to stabilize the mixer-phase is needed for the development of palladium hydride sensors. A method of synthesizing the mixer-phase palladium hydride in dimethylformamide at an elevated temperature has been reported. The synthesized palladium hydride can be stable under aerobic conditions. We used the stable palladium hydride to fabricate a pH microelectrode. In contrast to electrochemically generated palladium hydride microelectrodes, chemically generated palladium hydride microelectrodes are longer lasting and importantly have good an analytical performance under aerobic conditions. Chemically generated palladium hydride microelectrodes perform best in acid to neutral electrolytes devoid of Cl-. They can readily be produced on 10 µm diameter disk platinum microelectrodes, which makes them attractive candidates for future localized electrochemical studies.
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Malik, M. Rizwan, Tie Lin Shi, and Zi Rong Tang. "Trapping and Manipulation of Bioparticles by a 3-D Optimal Multiple-Designed Offset Carbon-Microelectrode Array in C-MEMS Fabrication." Journal of Biomimetics, Biomaterials and Tissue Engineering 10 (May 2011): 25–42. http://dx.doi.org/10.4028/www.scientific.net/jbbte.10.25.
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A dielectrophoretic approach with latest developed three-dimensional (3-D) carbon micro-electro-mechanical system (C-MEMS) has been extended as a potential route with idyllic solution to recommend a low-cost, biocompatible and high throughput manipulation and positioning for bio-particles as compared to 2D-planar microelectrodes. Presented in this paper is a novel platform for modelling and simulation of C-MEMS microfabrication process for dielectrophoresis (DEP) force based on various 3-D offset-microelectrode configurations. Numerical solutions are employed to investigate the upshots of multi-designed microelectrodes, applied voltage, electrode edge-to-edge gap and geometric size of microelectrodes on the electric field intensity gradient, induced by an AC voltage for the deployment of broad categories of bioparticles creation, utilization and their manipulation (separation, concentration, transportation and focusing). Sharp edge electrodes are the principle focus of this paper for DEP manipulation that is more convenient to enhance the electric field intensity distribution. The results show that square column electrodes configuration comparatively create large gradient magnitude in electric field intensity as compared to all other configurations. It is also observed that electric field extends drastically with increases in microelectrode height. These findings are consistent with literature experimental reports and will provide vital strategy for optimal design of DEP devices with 3-D C-MEMS.
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Tan, Chao, Haocheng Yin, Victoria Brooks, Prabhu U. Arumugam, and Shabnam Siddiqui. "A Study of the Effect of Electrochemical Roughening of Platinum on the Sensitivity and Selectivity of Glutamate Biosensors." Journal of The Electrochemical Society 169, no. 3 (March 1, 2022): 037510. http://dx.doi.org/10.1149/1945-7111/ac5ad5.
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A systematic study of electrochemically roughened (ECR) thin film platinum (Pt) microelectrodes for glutamate, GLU (a major excitatory neurotransmitter) detection is presented. Scanning electron microscopy, energy dispersive spectroscopy, surface profilometry, electrochemical impedance spectroscopy and amperometry techniques were applied to investigate the effect of high-frequency electrical pulses on Pt microelectrode roughness, electroactive area, charge transfer resistance, and sensitivity and selectivity to hydrogen peroxide, a by-product of enzymatic biosensors and GLU. An increase in the mean surface roughness from 9.0 ± 0.5 to 116.3 ± 7.4 nm (n = 3) was observed which resulted in a 55 ± 2% (n = 3) increase in the electroactive area. An ECR microelectrode treated at +1.4 V and coated with a selective coating produced a GLU selectivity value of 342 ± 34 (n = 3) vs ascorbic acid and the highest GLU sensitivity of 642 ± 45 nAμM−1cm−2 (n = 3) when compared to other surface-treated Pt microelectrodes reported in the literature. An impedance model was created to elucidate the microstructural and electrochemical property changes to the ECR microelectrodes. The ECR surface comprises of uniformly distributed homogenous pores with very low impedance, which is ∼6-times lower when compared to a methanol cleaned electrode. The model could lay a foundation for the rational designing of biosensors for enhanced neurotransmitter detection.
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Xu, Meng, Yuewu Zhao, Guanghui Xu, Yuehu Zhang, Shengkai Sun, Yan Sun, Jine Wang, and Renjun Pei. "Recent Development of Neural Microelectrodes with Dual-Mode Detection." Biosensors 13, no. 1 (December 30, 2022): 59. http://dx.doi.org/10.3390/bios13010059.
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Neurons communicate through complex chemical and electrophysiological signal patterns to develop a tight information network. A physiological or pathological event cannot be explained by signal communication mode. Therefore, dual-mode electrodes can simultaneously monitor the chemical and electrophysiological signals in the brain. They have been invented as an essential tool for brain science research and brain-computer interface (BCI) to obtain more important information and capture the characteristics of the neural network. Electrochemical sensors are the most popular methods for monitoring neurochemical levels in vivo. They are combined with neural microelectrodes to record neural electrical activity. They simultaneously detect the neurochemical and electrical activity of neurons in vivo using high spatial and temporal resolutions. This paper systematically reviews the latest development of neural microelectrodes depending on electrode materials for simultaneous in vivo electrochemical sensing and electrophysiological signal recording. This includes carbon-based microelectrodes, silicon-based microelectrode arrays (MEAs), and ceramic-based MEAs, focusing on the latest progress since 2018. In addition, the structure and interface design of various types of neural microelectrodes have been comprehensively described and compared. This could be the key to simultaneously detecting electrochemical and electrophysiological signals.
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Ibrahim, Siti Noorjannah, and Maan M. Alkaisi. "Microelectrode Design for Particle Trapping on Bioanalysis Platform." Advanced Materials Research 1115 (July 2015): 543–48. http://dx.doi.org/10.4028/www.scientific.net/amr.1115.543.
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Microelectrode geometry has significant influence on particles trapping techniques used on bioanalysis platforms. In this paper, the particle trapping patterns of dipole, quadrupole and octupole microelectrode using dielectrophoretic force (DEP) are discussed. The microelectrodes were constructed on a metal-insulator-metal platform, built on a silicon nitride (Si3N4) coated silicon substrate. The back contact is made from 20 nm nickel-chromium (NiCr) and 100 nm gold (Au) as the first layer. Then, SU-8-2005 (negative photoresist) is used on the second layer to create microcavities for trapping the particles. The third layer, where the three geometries were patterned, is made from 20 nm NiCr and 100 nm Au layers. Prior to fabrication, the particles trapping patterns of the microelectrodes were profiled using a finite element software, COMSOL 3.5a. Trapping patterns for the three geometries were evaluated using polystyrene latex microbeads. Results from the experiment validate simulation studies in term of microelectrode trapping ability up to single particle efficiency. It provides the potential of converting the trapping platform into a lab-on-chip system.
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Mason, M. J. "Qualitative measurements of the entry of L-lactate into single surface fibres of frog skeletal muscle using a lactate-sensitive microelectrode." Canadian Journal of Physiology and Pharmacology 65, no. 12 (December 1, 1987): 2488–91. http://dx.doi.org/10.1139/y87-394.
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The present results demonstrate the sensitivity of the Corning chloride liquid ion exchanger 477913 to L-lactate. Microelectrodes filled with this exchanger showed responses to changes in L-lactate concentration in chloride-free solutions. In these experiments L-lactate replaced gluconate in equimolar amounts. Microelectrodes filled with this exchanger were used to qualitatively detect changes in intracellular anion in chloride-depleted frog sartorius muscle fibres during exposure to extracellular concentrations of L-lactate. The increase in intracellular anion concentration is consistent with the movement of L-lactate into the cell. This microelectrode enables one to qualitatively monitor changes in intracellular L-lactate in chloride-free experiments without incorporating selectivity coefficients.
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Omichi, Chikaya, Moon-Hyoung Lee, Toshihiko Ohara, Ajay M. Naik, Nina C. Wang, Hrayr S. Karagueuzian, and Peng-Sheng Chen. "Comparing cardiac action potentials recorded with metal and glass microelectrodes." American Journal of Physiology-Heart and Circulatory Physiology 279, no. 6 (December 1, 2000): H3113—H3117. http://dx.doi.org/10.1152/ajpheart.2000.279.6.h3113.
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Machine-pulled high-impedance glass capillary microelectrode is standard for transmembrane potential (TMP) recordings. However, it is fragile and difficult to impale, especially in beating myocardial tissues. We hypothesize that a high-impedance pure iridium metal electrode can be used as an alternative to the glass microelectrode for TMP recording. The TMPs were simultaneously recorded from isolated perfused swine right ventricles with a metal microelectrode and a standard glass microelectrode during pacing and during ventricular fibrillation. The basic morphology of TMP recorded with these electrodes was comparable. The action potential duration (APD) at 90% repolarization was 241 ± 29 ms for the metal microelectrode and 236 ± 31 ms for the glass microelectrode with a good correlation ( r = 0.99, P < 0.0001). The maximum slope value of the APD restitution curves during pacing was also significantly correlated. One metal microelectrode and >20 glass microelectrodes were needed per study. We conclude that, in isolated perfused swine right ventricles, the TMP recorded by the metal microelectrode is comparable with that recorded by the glass microelectrode. Because the metal microelectrode is more durable than the glass microelectrode, it can serve as an alternative for APD recording and for restitution analyses.
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Zeng, Qi, Shoujun Yu, Zihui Fan, Yubin Huang, Bing Song, and Tian Zhou. "Nanocone-Array-Based Platinum-Iridium Oxide Neural Microelectrodes: Structure, Electrochemistry, Durability and Biocompatibility Study." Nanomaterials 12, no. 19 (October 1, 2022): 3445. http://dx.doi.org/10.3390/nano12193445.
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Neural interfaces provide a window for bio-signal modulation and recording with the assistance of neural microelectrodes. However, shrinking the size of electrodes results in high electrochemical impedance and low capacitance, thus limiting the stimulation/recording efficiency. In order to achieve critical stability and low power consumption, here, nanocone-shaped platinum (Pt) with an extensive surface area is proposed as an adhesive layer on a bare Pt substrate, followed by the deposition of a thin layer of iridium oxide (IrOx) to fabricate high-performance nanocone-array-based Pt-IrOx neural microelectrodes (200 μm in diameter). A uniform nanocone-shaped Pt with significant roughness is created via controlling the ratio of NH4+ and Pt4+ ions in the electrolyte, which can be widely applicable for batch production on multichannel flexible microelectrode arrays (fMEAs) and various substrates with different dimensions. The Pt-IrOx nanocomposite-coated microelectrode presents a significantly low impedance down to 0.72 ± 0.04 Ω cm2 at 1 kHz (reduction of ~92.95%). The cathodic charge storage capacity (CSCc) and charge injection capacity (CIC) reaches up to 52.44 ± 2.53 mC cm−2 and 4.39 ± 0.36 mC cm−2, respectively. Moreover, superior chronic stability and biocompatibility are also observed. The modified microelectrodes significantly enhance the adhesion of microglia, the major immune cells in the central nervous system. Therefore, such a coating strategy presents great potential for biomedical and other practical applications.
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Wang, Chia-Lin, Kenneth E. Creasy, and Brenda R. Shaw. "Ring-modified carbon fiber microelectrodes and multi-microelectrode devices." Journal of Electroanalytical Chemistry and Interfacial Electrochemistry 300, no. 1-2 (February 1991): 365–75. http://dx.doi.org/10.1016/0022-0728(91)85405-e.
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Todd, Elizabeth A., and Michael D. Morris. "Micron Surface-Enhanced Raman Spectroscopy of Intact Biological Organisms and Model Systems." Applied Spectroscopy 48, no. 5 (May 1994): 545–48. http://dx.doi.org/10.1366/0003702944924790.
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Surface-enhanced Raman spectra have been obtained within intact zebrafish embryos and inside the 500-fL pores of a Nucleopore filter membrane with the use of coated microelectrodes with 1–3 μm active silver tip diameters. The spectra obtained demonstrate the microelectrode's ability to penetrate biological membranes as well as restricted volumes.
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Zhao, Huiqing, Ruping Liu, Huiling Zhang, Peng Cao, Zilong Liu, and Ye Li. "Research Progress on the Flexibility of an Implantable Neural Microelectrode." Micromachines 13, no. 3 (February 28, 2022): 386. http://dx.doi.org/10.3390/mi13030386.
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Neural microelectrode is the important bridge of information exchange between the human body and machines. By recording and transmitting nerve signals with electrodes, people can control the external machines. At the same time, using electrodes to electrically stimulate nerve tissue, people with long-term brain diseases will be safely and reliably treated. Young’s modulus of the traditional rigid electrode probe is not matched well with that of biological tissue, and tissue immune rejection is easy to generate, resulting in the electrode not being able to achieve long-term safety and reliable working. In recent years, the choice of flexible materials and design of electrode structures can achieve modulus matching between electrode and biological tissue, and tissue damage is decreased. This review discusses nerve microelectrodes based on flexible electrode materials and substrate materials. Simultaneously, different structural designs of neural microelectrodes are reviewed. However, flexible electrode probes are difficult to implant into the brain. Only with the aid of certain auxiliary devices, can the implant be safe and reliable. The implantation method of the nerve microelectrode is also reviewed.
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Mousavi, Hajar, Gautier Dauly, Gabriel Dieuset, Amira El Merhie, Esma Ismailova, Fabrice Wendling, and Mariam Al Harrach. "Tuning Microelectrodes’ Impedance to Improve Fast Ripples Recording." Bioengineering 11, no. 1 (January 22, 2024): 102. http://dx.doi.org/10.3390/bioengineering11010102.
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Epilepsy is a chronic neurological disorder characterized by recurrent seizures resulting from abnormal neuronal hyperexcitability. In the case of pharmacoresistant epilepsy requiring resection surgery, the identification of the Epileptogenic Zone (EZ) is critical. Fast Ripples (FRs; 200–600 Hz) are one of the promising biomarkers that can aid in EZ delineation. However, recording FRs requires physically small electrodes. These microelectrodes suffer from high impedance, which significantly impacts FRs’ observability and detection. In this study, we investigated the potential of a conductive polymer coating to enhance FR observability. We employed biophysical modeling to compare two types of microelectrodes: Gold (Au) and Au coated with the conductive polymer poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (Au/PEDOT:PSS). These electrodes were then implanted into the CA1 hippocampal neural network of epileptic mice to record FRs during epileptogenesis. The results showed that the polymer-coated electrodes had a two-order lower impedance as well as a higher transfer function amplitude and cut-off frequency. Consequently, FRs recorded with the PEDOT:PSS-coated microelectrode yielded significantly higher signal energy compared to the uncoated one. The PEDOT:PSS coating improved the observability of the recorded FRs and thus their detection. This work paves the way for the development of signal-specific microelectrode designs that allow for better targeting of pathological biomarkers.
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Anderson, Grace C., Siddharth Rajupet, John G. Petrovick, Douglas I. Kushner, Alexis T. Bell, and Adam Z. Weber. "Exploring Proton Activity at the Membrane/Electrode Interface with Microelectrodes." ECS Transactions 112, no. 4 (September 29, 2023): 323–32. http://dx.doi.org/10.1149/11204.0323ecst.
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Microelectrode measurements using a polycrystalline platinum microelectrode were used to simulate the membrane/electrode interface of a membrane-electrode-assembly (MEA) architecture. The proton activity for the hydrogen-evolution reaction (HER) was evaluated for 40, 60, and 80% relative humidity. Proton activity was calculated to be 0.5, 1.0 and 2.0 for 40, 60, and 80% relative humidity, respectively, using open circuit potential measurements between Nafion 211 and 1 molal HClO4. The fraction of protons which dissociate at a given relative humidity condition appears to be a distinctive factor in proton activity for Nafion 211 compared to an aqueous electrolyte. The microelectrode measurements exhibited a Tafel slope of ~120 mV/dec, similar to that observed for platinum in MEA systems, demonstrating that kinetic measurements made with microelectrodes can be representative of MEA kinetics.
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Song, Sydney, Brianna Regan, Evon Ereifej, E. Chan, and Jeffrey Capadona. "Neuroinflammatory Gene Expression Analysis Reveals Pathways of Interest as Potential Targets to Improve the Recording Performance of Intracortical Microelectrodes." Cells 11, no. 15 (July 30, 2022): 2348. http://dx.doi.org/10.3390/cells11152348.
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Intracortical microelectrodes are a critical component of brain-machine interface (BMI) systems. The recording performance of intracortical microelectrodes used for both basic neuroscience research and clinical applications of BMIs decreases over time, limiting the utility of the devices. The neuroinflammatory response to the microelectrode has been identified as a significant contributing factor to its performance. Traditionally, pathological assessment has been limited to a dozen or so known neuroinflammatory proteins, and only a few groups have begun to explore changes in gene expression following microelectrode implantation. Our initial characterization of gene expression profiles of the neuroinflammatory response to mice implanted with non-functional intracortical probes revealed many upregulated genes that could inform future therapeutic targets. Emphasis was placed on the most significant gene expression changes and genes involved in multiple innate immune sets, including Cd14, C3, Itgam, and Irak4. In previous studies, inhibition of Cluster of Differentiation 14 (Cd14) improved microelectrode performance for up to two weeks after electrode implantation, suggesting CD14 can be explored as a potential therapeutic target. However, all measures of improvements in signal quality and electrode performance lost statistical significance after two weeks. Therefore, the current study investigated the expression of genes in the neuroinflammatory pathway at the tissue-microelectrode interface in Cd14−/− mice to understand better how Cd14 inhibition was connected to temporary improvements in recording quality over the initial 2-weeks post-surgery, allowing for the identification of potential co-therapeutic targets that may work synergistically with or after CD14 inhibition to improve microelectrode performance.
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Paffi, A., F. Apollonio, M. G. Puxeddu, M. Parazzini, G. d’Inzeo, P. Ravazzani, and M. Liberti. "A Numerical Study to Compare Stimulations by Intraoperative Microelectrodes and Chronic Macroelectrodes in the DBS Technique." BioMed Research International 2013 (2013): 1–7. http://dx.doi.org/10.1155/2013/262739.
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Deep brain stimulation is a clinical technique for the treatment of parkinson’s disease based on the electric stimulation, through an implanted electrode, of specific basal ganglia in the brain. To identify the correct target of stimulation and to choose the optimal parameters for the stimulating signal, intraoperative microelectrodes are generally used. However, when they are replaced with the chronic macroelectrode, the effect of the stimulation is often very different. Here, we used numerical simulations to predict the stimulation of neuronal fibers induced by microelectrodes and macroelectrodes placed in different positions with respect to each other. Results indicate that comparable stimulations can be obtained if the chronic macroelectrode is correctly positioned with the same electric center of the intraoperative microelectrode. Otherwise, some groups of fibers may experience a completely different electric stimulation.
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PARK, W. B., J. H. CHOI, C. W. PARK, G. M. KIM, H. S. SHIN, C. N. CHU, and B. H. KIM. "FABRICATION OF MICRO PROBE-TYPE ELECTRODES FOR MICROELECTRO-CHEMICAL MACHINING USING MICROFABRICATION." International Journal of Modern Physics B 24, no. 15n16 (June 30, 2010): 2639–44. http://dx.doi.org/10.1142/s0217979210065398.
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In this study, the mass fabrication of microelectrode tools for microelectrochemical machining (MECM) was studied using microfabrication processes. The cantilever type geometry of microelectrodes was defined by photolithography processes, and metal patterns were made for electrical contacts. Various fabrication processes were studied for the fabrication of microelectrode tools, such as wet etching, lift-off, and electroforming for metal layer patterning. MECM test results showed feasibility of the fabricated electrode tools. The microfabricated electrodes can be used as micromachining tools for various electrical micromachining of steel mold and parts of microdevices.
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Hay, Catherine E., Junqiao Lee, and Debbie S. Silvester. "Formation of 3-Dimensional Gold, Copper and Palladium Microelectrode Arrays for Enhanced Electrochemical Sensing Applications." Nanomaterials 9, no. 8 (August 15, 2019): 1170. http://dx.doi.org/10.3390/nano9081170.
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Microelectrodes offer higher current density and lower ohmic drop due to increased radial diffusion. They are beneficial for electroanalytical applications, particularly for the detection of analytes at trace concentrations. Microelectrodes can be fabricated as arrays to improve the current response, but are presently only commercially available with gold or platinum electrode surfaces, thus limiting the sensing of analytes that are more electroactive on other surfaces. In this work, gold (Au), copper (Cu), and palladium (Pd) are electrodeposited at two different potentials into the recessed holes of commercial microelectrode arrays to produce 3-dimensional (3D) spiky, dendritic or coral-like structures. The rough fractal structures that are produced afford enhanced electroactive surface area and increased radial diffusion due to the 3D nature, which drastically improves the sensitivity. 2,4,6-trinitrotoluene (TNT), carbon dioxide gas (CO2), and hydrogen gas (H2) were chosen as model analytes in room temperature ionic liquid solvents, to demonstrate improvements in the sensitivity of the modified microelectrode arrays, and, in some cases (e.g., for CO2 and H2), enhancements in the electrocatalytic ability. With the deposition of different materials, we have demonstrated enhanced sensitivity and electrocatalytic behaviour towards the chosen analytes.
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Peckova, Karolina, and Jiri Barek. "Boron Doped Diamond Microelectrodes and Microelectrode Arrays in Organic Electrochemistry." Current Organic Chemistry 15, no. 17 (September 1, 2011): 3014–28. http://dx.doi.org/10.2174/138527211798357164.
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Long, John T., and Stephen G. Weber. "Noise at microelectrodes and microelectrode arrays in amperometry and voltammetry." Analytical Chemistry 60, no. 20 (October 15, 1988): 2309–11. http://dx.doi.org/10.1021/ac00171a032.
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Shen, Junyu, Yanyan Xu, Zhengwen Xiao, Yuebo Liu, Honghui Liu, Fengge Wang, Wanqing Yao, et al. "Influence of the Surface Material and Illumination upon the Performance of a Microelectrode/Electrolyte Interface in Optogenetics." Micromachines 12, no. 9 (August 31, 2021): 1061. http://dx.doi.org/10.3390/mi12091061.
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Integrated optrodes for optogenetics have been becoming a significant tool in neuroscience through the combination of offering accurate stimulation to target cells and recording biological signals simultaneously. This makes it not just be widely used in neuroscience researches, but also have a great potential to be employed in future treatments in clinical neurological diseases. To optimize the integrated optrodes, this paper aimed to investigate the influence of surface material and illumination upon the performance of the microelectrode/electrolyte interface and build a corresponding evaluation system. In this work, an integrated planar optrode with a blue LED and microelectrodes was designed and fabricated. The charge transfer mechanism on the interface was theoretically modeled and experimentally verified. An evaluation system for assessing microelectrodes was also built up. Using this system, the proposed model of various biocompatible surface materials on microelectrodes was further investigated under different illumination conditions. The influence of illumination on the microelectrode/electrolyte interface was the cause of optical artifacts, which interfere the biological signal recording. It was found that surface materials had a great effect on the charge transfer capacity, electrical stability and recoverability, photostability, and especially optical artifacts. The metal with better charge transfer capacity and electrical stability is highly possible to have a better performance on the optical artifacts, regardless of its electrical recoverability and photostability under the illumination conditions of optogenetics. Among the five metals used in our investigation, iridium served as the best surface material for the proposed integrated optrodes. Thus, optimizing the surface material for optrodes could reduce optical interference, enhance the quality of the neural signal recording for optogenetics, and thus help to advance the research in neuroscience.
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Zou, Zhixiang, Zhongning Guo, Qinming Huang, Taiman Yue, Jiangwen Liu, and Xiaolei Chen. "Precision EDM of Micron-Scale Diameter Hole Array Using in-Process Wire Electro-Discharge Grinding High-Aspect-Ratio Microelectrodes." Micromachines 12, no. 1 (December 26, 2020): 17. http://dx.doi.org/10.3390/mi12010017.
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Micro-electrical discharge machining (micro-EDM) is a good candidate for processing micro-hole arrays, which are critical features of micro-electro-mechanical systems (MEMS), diesel injector nozzles, inkjet printheads and turbine blades, etc. In this study, the wire vibration of the wire electro-discharge grinding (WEDG) system has been analyzed theoretically, and, accordingly, an improved WEDG method was developed to fabricate micron-scale diameter and high-aspect-ratio microelectrodes for the in-process micro-EDM of hole array with hole diameter smaller than 20 μm. The improved method has a new feature of a positioning device to address the wire vibration problem, and thus to enhance microelectrodes fabrication precision. Using this method, 14 μm diameter microelectrodes with less than 0.4 μm deviation and an aspect ratio of 142, which is the largest aspect ratio ever reported in the literature, were successfully fabricated. These microelectrodes were then used to in-process micro-EDM of hole array in stainless steel. The effects of applied voltage, current and pulse frequency on hole dimensional accuracy and microelectrode wear were investigated. The optimal processing parameters were selected using response–surface experiments. To improve machining accuracy, an in-process touch-measurement compensation strategy was applied to reduce the cumulative compensation error of the micro-EDM process. Using such a system, micro-hole array (2 × 80) with average entrance diameter 18.91 μm and average exit diameter 17.65 μm were produced in 50 μm thickness stainless steel sheets, and standard deviations of hole entrance and exit sides of 0.44 and 0.38 μm, respectively, were achieved.
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Hinke, J. A. M. "Thirty years of ion-selective microelectrodes: disappointments and successes." Canadian Journal of Physiology and Pharmacology 65, no. 5 (May 1, 1987): 873–78. http://dx.doi.org/10.1139/y87-140.
Full textAbstract:
The need to know the intracellular activity of an ion and how it changes under controlled conditions is as important today as it was 30 years ago. In 1956, one could fabricate only a H+-selective microelectrode and with a tip size not much smaller than 100 μm. Today, one can fabricate microelectrodes selective to H+, Na+, K+, Cl−, HCO3−, Ca2+, or Mg2+ (plus others) and with active tips less than 1 μm. The reduction of active tip size can be attributed mainly to the introduction of liquid ion exchanger (LIX) and neutral carrier ligands. Unfortunately, the LIX microelectrodes, as currently fabricated, do not yet function optimally as reliable and stable electrochemical measuring devices. A durable bond between the active membrane and its insulated container continues to remain the major design problem even after 30 years of development.
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Zhelyaskov, Valentin R., Elizabeth T. Milne, Jamille F. Hetke, and Michael D. Morris. "Silicon Substrate Microelectrode Array for Surface-Enhanced Raman Spectroscopy." Applied Spectroscopy 49, no. 12 (December 1995): 1793–95. http://dx.doi.org/10.1366/0003702953966028.
Full textAbstract:
Electrode sites of a photolithographically fabricated microelectrode array have been demonstrated to function as surface-enhanced Raman Spectroscopy (SERS) microelectrodes. The 5 × 15 μm iridium electrodes on the substrate are electroplated with silver and activated by standard procedures. Working and counter-electrode functions are integrated onto the same assembly. The electrode is shown to yield adenosine and pyridine spectra at low concentrations and submilliwatt laser power.