Academic literature on the topic 'Thin Film Strain Gauges (TFSG)'

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Journal articles on the topic "Thin Film Strain Gauges (TFSG)"

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Cui, Yunxian, Xin Li, Tenglun Zhang, Wanyu Ding, and Junwei Yin. "Development of High-Temperature Wire-Grid Thin Film Strain Gauges." Sensors 22, no. 19 (October 7, 2022): 7595. http://dx.doi.org/10.3390/s22197595.

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Aero-engine turbine stator blades are often used in harsh environments with high temperatures and high pressure and are prone to fatigue fractures. Real-time and accurate monitoring of blade surface stress and strain is critical to ensure safe operation. In this study, thin-film strain gauges (TFSGs) that can be used in high-temperature environments above 1000 °C were designed and fabricated using a PtRh6 thin film as the sensitive material. The hysteresis effect of the stress transfer upon establishing a thermo-mechanical coupling finite element model of the Inconel718 high-temperature nickel-based alloy equal-strength beam PtRh6 TFSGs was analyzed and the optimal combination of thin-film thickness and longitudinal grid length of wire-grid TFSGs was determined. In order to solve the problem of high-temperature insulation, the insulating properties of a single-layer Al2O3 insulating film, a single-layer ZrO2 insulating film, a double-layer Al2O3/ZrO2 composite insulating film, and a four-layer Al2O3/ZrO2/Al2O3/ZrO2 composite insulating film at high temperature were compared and studied using scanning electron microscopy to analyze the microscopic morphology and composition of the four insulating film structures. The results showed that the four-layer Al2O3/ZrO2/Al2O3/ZrO2 composite insulating film had the best insulating properties at high temperatures. On this basis, an Al2O3/ZrO2/Al2O3/ZrO2 composite insulating film, PtRh6 sensitive layer, and Al2O3 protective film were sequentially deposited on a high-temperature nickel-based alloy equal-strength beam using DC pulsed magnetron sputtering technology to obtain an Inconel718 high-temperature nickel-based alloy equal-strength beam PtRh6 TFSG. Its gauge factor (GF) and temperature coefficient of resistance (TCR) were calibrated, and the results showed that the sensor could be used in harsh environments of 1000 °C. The above results provide new ideas for measuring stress and strain in aerospace under high-temperature and high-pressure environments.
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Li, Chunshien, P. J. Hesketh, and G. J. Maclay. "Thin gold film strain gauges." Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films 12, no. 3 (May 1994): 813–19. http://dx.doi.org/10.1116/1.578828.

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Kayser, P., J. C. Godefroy, and L. Leca. "High-temperature thin-film strain gauges." Sensors and Actuators A: Physical 37-38 (June 1993): 328–32. http://dx.doi.org/10.1016/0924-4247(93)80055-l.

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Lin, Fan, Xiaochuan Pan, Chao Wu, Yingjun Zeng, Guochun Chen, Qinnan Chen, Daoheng Sun, and Zhenyin Hai. "ZrB2/SiCN Thin-Film Strain Gauges for In-Situ Strain Detection of Hot Components." Micromachines 13, no. 9 (September 4, 2022): 1467. http://dx.doi.org/10.3390/mi13091467.

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The in-situ strain/stress detection of hot components in harsh environments remains a challenging task. In this study, ZrB2/SiCN thin-film strain gauges were fabricated on alumina substrates by direct writing. The effects of ZrB2 content on the electrical conductivity and strain sensitivity of ZrB2/SiCN composites were investigated, and based on these, thin film strain gauges with high electrical conductivity (1.71 S/cm) and a gauge factor of 4.8 were prepared. ZrB2/SiCN thin-film strain gauges exhibit excellent static, cyclic strain responses and resistance stability at room temperature. In order to verify the high temperature performance of the ZrB2/SiCN thin-film strain gauges, the temperature-resistance characteristic curves test, high temperature resistance stability test and cyclic strain test were conducted from 25 °C to 600 °C. ZrB2/SiCN thin-film strain gauges exhibit good resistance repeatability and stability, and highly sensitive strain response, from 25 °C to 600 °C. Therefore, ZrB2/SiCN thin-film strain gauges provide an effective approach for the measurement of in-situ strain of hot components in harsh environments.
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Broitman, E., and R. Zimmerman. "Ion-plated discontinuous thin film strain gauges." Thin Solid Films 317, no. 1-2 (April 1998): 440–42. http://dx.doi.org/10.1016/s0040-6090(97)00637-8.

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Schmaljohann, F., D. Hagedorn, and F. Löffler. "Thin film sensors for measuring small forces." Journal of Sensors and Sensor Systems 4, no. 1 (February 23, 2015): 91–95. http://dx.doi.org/10.5194/jsss-4-91-2015.

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Abstract. Especially in the case of measuring small forces, the use of conventional foil strain gauges is limited. The measurement uncertainty rises by force shunts and is due to the polymer foils used, as they are susceptible to moisture. Strain gauges in thin film technology present a potential solution to overcome these effects because of their direct and atomic contact with the measuring body, omitting an adhesive layer and the polymer foil. For force measurements up to 1 N, a suitable deformation element was developed by finite element (FE) analysis. This element is designed for an approximate strain of 1000 μm m−1 at the designated nominal load. The thin film system was applied by magnetron sputtering. The strain gauge structure is fabricated by distinct photolithographic steps. The developed sensors were tested with different load increments. The functional capability of the single resistance strain gauges could be proven. Moreover, a developed sensor in a full bridge circuit showed a linear characteristic with low deviation and good stability.
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Mathis, Maximilian, Dennis Vollberg, Matthäus Langosch, Dirk Göttel, Angela Lellig, and Günter Schultes. "Creep adjustment of strain gauges based on granular NiCr-carbon thin films." Journal of Sensors and Sensor Systems 10, no. 1 (March 12, 2021): 53–61. http://dx.doi.org/10.5194/jsss-10-53-2021.

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Abstract. An important property of high-precision mechanical sensors such as force transducers or torque sensors is the so-called creep error. It is defined as the signal deviation over time at a constant load. Since this signal deviation results in a reduced accuracy of the sensor, it is beneficial to minimize the creep error. Many of these sensors consist of a metallic spring element and strain gauges. In order to realize a sensor with a creep error of almost zero, it is necessary to compensate for the creep behavior of the metallic spring element. This can be achieved by creep adjustment of the used strain gauges. Unlike standard metal foil strain gauges with a gauge factor of 2, a type of strain gauges based on sputter-deposited NiCr-carbon thin films on polymer substrates offers the advantage of an improved gauge factor of about 10. However, for this type of strain gauge, creep adjustment by customary methods is not possible. In order to remedy this disadvantage, a thorough creep analysis is carried out. Five major influences on the creep error of force transducers equipped with NiCr-carbon thin-film strain gauges are examined, namely, the material creep of the metallic spring element (1), the creep (relaxation) of the polymer substrate (2), the composition of the thin film (3), the strain transfer to the thin film (4), and the kind of strain field on the surface of the transducer (5). Consequently, we present two applicable methods for creep adjustment of NiCr-carbon thin- film strain gauges. The first method addresses the intrinsic creep behavior of the thin film by a modification of the film composition. With increasing Cr content (at the expense of Ni, the intrinsic negative creep error can be shifted towards zero. The second method is not based on the thin film itself but rather on a modification of the strain transfer from the polyimide carrier to the thin film. This is achieved by controlled cutting of well-defined deep trenches into the polymer substrate via a picosecond laser.
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Grange, H., C. Maeder, C. Bieth, S. Renard, and G. Delapierre. "Thin film strain gauges on polymers: main characteristics." Sensors and Actuators A: Physical 46, no. 1-3 (January 1995): 213–17. http://dx.doi.org/10.1016/0924-4247(94)00892-l.

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Mathis, Maximilian, Dennis Vollberg, Matthäus Langosch, Dirk Göttel, Angela Lellig, and Günter Schultes. "Novel method to reduce the transverse sensitivity of granular thin film strain gauges by modification of strain transfer." Journal of Sensors and Sensor Systems 9, no. 2 (July 17, 2020): 219–26. http://dx.doi.org/10.5194/jsss-9-219-2020.

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Abstract. Strain gauges based on polyimide carrier foils and piezoresistive granular thin films are highly sensitive to strain. Unlike conventional metal foil, granular film strain gauges also have a pronounced sensitivity to strain acting in the transverse direction. A novel method that allows for the modification of the strain transfer is proposed and proven experimentally. The method is based on the creation of stand-alone polyimide paths, on top of which the piezoresistive thin film is located. In this way, the granular film hardly receives any transverse strain; hence, the transverse sensitivity is drastically reduced. A picosecond laser system can be used for both patterning of the thin film and for controlled ablation of polyimide in order to generate well-defined high path structures. The working principle of the method is demonstrated by simulation, followed by an experimental verification using measurements of the transverse gauge factor. Furthermore, the output signal of force transducers may be increased using granular thin film strain gauges of reduced transverse sensitivity.
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Brandt, Bjoern, Marion Gemeinert, Ralf Koppert, Jochen Bolte, and Torsten Rabe. "LTCC Substrates for High Performance Strain Gauges." Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2012, CICMT (September 1, 2012): 000175–80. http://dx.doi.org/10.4071/cicmt-2012-tp43.

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Recent advances in the development of high gauge factor thin-films for strain gauges prompt the research on advanced substrate materials. A glass ceramic composite has been developed in consideration of a high coefficient of thermal expansion and a low modulus of elasticity for the application as support material for thin-film sensors. Constantan foil strain gauges were fabricated from this material by tape casting, pressure-assisted sintering and subsequent lamination of the metal foil on the planar ceramic substrates. The sensors were mounted on a strain gauge beam arrangement and load curves and creep behavior were evaluated. The accuracy of the assembled load cells correspond to accuracy class C6. That qualifies the load cells for the use in automatic packaging units and confirms the applicability of the LTCC substrates for fabrication of accurate strain gauges. To facilitate the deposition of thin film sensor structures onto the LTCC substrates, the pressure-assisted sintering technology has been refined. By the use of smooth setters instead of release tapes substrates with minimal surface roughness were fabricated. Metallic thin films deposited on these substrates exhibit low surface resistances comparable to thin films on commercial alumina thin-film substrates. The presented advances in material design and manufacturing technology are important to promote the development of high performance thin-film strain gauges.
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Dissertations / Theses on the topic "Thin Film Strain Gauges (TFSG)"

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Au, Daniel Tak Yin. "Evaporation cast thin film carbon nanotube strain gauges." Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/44860.

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This work describes the research performed on synthesising and measuring the gauge factor of evaporation cast thin film carbon nanotube strain gauges. The main characteristics pursued of the strain gauges are inexpensive, easily manufactured and reasonably sensitive. Carbon nanotubes have exhibited a high gauge factor due to their intrinsic piezoresistivity and were incorporated into evaporation cast films to try to take advantage of the high sensitivity. Another direction taken to improve the sensitivity is alignment of carbon nanotubes in the thin film. Previous work produced an evaporation cast carbon nanotube strain gauge with a relatively high gauge factor. However, it was not reproducible and the research encompassed extends from the previous work. A number of ink compositions with different carbon nanotube and surfactant loadings were used to synthesise thin films of carbon nanotubes on a polyimide substrate. Variations of evaporation casting were used to decrease the evaporation rate in attempts of carbon nanotube alignment through a self-organising liquid crystal phase during evaporation. Other methods of inkjet printing and air flow evaporation casting were also attempted to achieve alignment. Electrical connections using a conductive polymer and metal wires were fabricated onto the samples for electrical measurements. A four-point probe resistance measurement under the application of strain was used to elicit the gauge factors. The strain gauge design was modified from previous work for more reliable electrical connections and for higher applied strains. A procedure for electrical measurements coupled with the application of strain was devised and the gauge factors achieved varied between 0.1 and 4.0 with a median of 1.1 ±0.1. The median gauge factor was reproducible and exhibited by several samples fabricated with different types of evaporation casting. The decrease in evaporation rate did not result in either alignment or relatively high gauge factors. In general, alignment was not achieved with the other methods of air flow evaporation and inkjet printing.
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Djugum, Richard, and n/a. "Novel fabrication processes for thin film vapour deposited strain gauges on mild steel." Swinburne University of Technology, 2006. http://adt.lib.swin.edu.au./public/adt-VSWT20070424.115951.

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Pressure measurement using a strain gauge bonded with epoxy adhesive to a metallic mechanical support has been, and still is, extensively employed, however, for some applications the use of an epoxy is inadequate, especially when temperatures exceed 120C. There is therefore particular interest in the use of thin film techniques to vacuum deposit strain gauges directly on metallic substrates. Such devices are highly cost effective when produced in large quantities due to the manufacturing techniques involved. This makes them ideally suited for use in large-volume products such as electronic weighing scales and pressure transducers. In this thesis, new techniques for fabricating thin film vapour deposited strain gauge transducers on metal substrates for application as novel pressure sensors in the fastener industry are developed. Clearly, for a vapour deposited strain gauge to function correctly, it is essential that it be deposited on a defect free, high quality electrically insulating film. This was a significant challenge in the present study since all available physical vapour deposition (PVD) equipment was direct current (DC) and insulators of around 4 um thick were needed to electrically isolate the strain gauges from metal. As a result, several methods of depositing insulators using DC were developed. The first involved the use of DC magnetron sputtering from an aluminium target to reactively deposit up to 4 um thick AlN. DC magnetron discharges suffer arc instability as the AlN forms on the target and this limits the maximum thickness that can be deposited. Consequently, the arc instability was suppressed manually by increasing argon gas flow at the onset of arcing. Although the deposited AlN showed a high insulating resistance, it was found that the breakdown voltage could significantly increase by (a) utilising a metallic interlayer between the thin film insulator and the metallic substrate and (b) annealing in air at 300C. A second deposition method involved the use of DC magnetron sputtering to deposit modulated thin film insulators in which an aluminium target was used to reactively deposit alternating layers of aluminium nitride and aluminium oxide. These films showed significant increases in average breakdown voltage when the number of layers within the composite film was increased. The third method involved the deposition of AlN thin film insulators using partially filtered cathodic arc evaporation with shielding. Initially, AlN was deposited under partially filtered conditions to obtain a relatively thick (~ 4 um) coating then, while still depositing under partially filtered conditions, a smooth top coating was deposited by using a shielding technique. The deposition of metal macroparticles is an inherent problem with cathodic arc deposition and shielding is one form of macroparticle filtering. Such particles are highly undesirable in this study as they are electrically conductive. A fourth coating technique for depositing insulators on steel was based on thermal spray technology. Insulating films of Al2O3 were plasma sprayed and then polished to thereby fabricate viable electrical insulators for vapour deposited strain gauges. With respect to depositing strain gauges two methods were employed. The first involved the sputter deposition of chromium through a shadow mask to form a strain gauge with gauge factor sensitivity of around 2. The second used cathodic arc evaporation to fabricate a multi-layered strain gauge composed of alternating CrN and TiAlN layers that yielded a gauge factor of around 3.5. The technique achieves better compatibility between gauge and insulator by allowing a wider selection of materials to form the gauge composition. Finally, a novel pressure sensor in the form of a load cell was developed that consisted of a chromium strain gauge on a steel washer electrically insulated with AlN thin film. The load cell showed good performance when tested under compressive load.
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Djugum, Richard. "Novel fabrication processes for thin film vapour deposited strain gauges on mild steel." Australasian Digital Thesis Program, 2006. http://adt.lib.swin.edu.au/public/adt-VSWT20070424.115951/index.html.

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Thesis (PhD) - Swinburne University of Technology, School of Engineering and Science, 2006.
A thesis submitted for the degree of Doctor of Philosophy, School of Engineering and Science, Swinburne University of Technology, 2006. Typescript. Includes bibliographical references (p. 125-138).
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Rajendra, A. "Pressure Sensor Development Using Hard Anodized Aluminum Diaphragm And Thin Film Strain Gauges." Thesis, 2006. http://hdl.handle.net/2005/344.

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The sensor is a device that converts a form of energy concerning which the information is sought, called the measurand, to a form (electrical) in which it can be usefully processed or interpreted. Sensors rely on physical or chemical phenomena and materials where those phenomena appear to be useful. Those phenomena may concern the material itself or its geometry. Hence, the major innovations in sensors come from new materials, new fabrication techniques or both. Normally, thin film sensors are realized by depositing a sensing film on a suitable substrate. There could be many combination of metals and insulating materials being deposited depending upon the application or sensing requirements. In general, sensors for various applications are fabricated using a variety of liquid phase technologies (also called as wet methods) and gas phase technologies (also called as dry methods) of deposition. Hence sensor fabrication technology requires various combination of processing technologies and newer materials. In the present work, an attempt is made to design and fabricate a thin film based pressure sensor using a combination of wet and dry deposition techniques. The diaphragm, used for sensing the pressure is coated with a hard anodic coating (Al2O3) using a wet technology, viz. pulse hard anodizing technique, for electrical insulation requirement. The piezo-resistive strain sensing films were deposited onto this coating by dry method, namely, DC Magnetron sputtering technique.. Chapter 01 gives a brief overview of sensors, their classification, principles of sensing,characteristics, materials used in the fabrication of sensors like conductors and insulators, the components of a sensor. Chapter 02 gives brief information about various techniques of depositions viz., liquid phase technologies (wet methods) and vapour phase technologies (dry methods) used to fabricate the sensors. Also, information regarding the coating property evaluation and coating characterization techniques is included. The chapter 03 presents a detailed account of work carried out to obtain an electrically insulating layer by the development of pulse hard anodizing process for aluminum alloy diaphragm, necessary process optimization and testing. The details related to the development, fabrication and testing of thin film based pressure sensors using aluminum alloy diaphragm with hard anodic coating are presented in Chapter 04. The thin film strain gauges were deposited using DC magnetron sputtering technique. The information about mask design, deposition process parameters, calibration etc is also included. Chapter 05 provides summary of the work carried out and conclusions. The scope of carrying out further work is also outlined.
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Stephen, R. John. "Development And Performance Study Of Ion Thrust Measurement System Using Strain Gauge Sensors." Thesis, 2005. http://etd.iisc.ernet.in/handle/2005/1463.

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Conference papers on the topic "Thin Film Strain Gauges (TFSG)"

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Suttmann, Oliver, Jan F. Duesing, Juergen Koch, and Ludger Overmeyer. "Laser patterning of thin film strain gauges." In ICALEO® 2013: 32nd International Congress on Laser Materials Processing, Laser Microprocessing and Nanomanufacturing. Laser Institute of America, 2013. http://dx.doi.org/10.2351/1.5062983.

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Suttmann, O., J. F. Duesing, J. Koch, U. Stute, and L. Overmeyer. "A1.3 - Patterning of thin film strain gauges on 3D-surfaces." In AMA Conferences 2013. AMA Service GmbH, Von-Münchhausen-Str. 49, 31515 Wunstorf, Germany, 2013. http://dx.doi.org/10.5162/sensor2013/a1.3.

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Ottermann, Rico, Daniel Klaas, Folke Dencker, Dominik Hoheisel, Sebastian Jung, Alexander Wienke, Jan Friedrich Dusing, Jurgen Koch, and Marc Christopher Wurz. "Directly Deposited Thin-Film Strain Gauges on Curved Metallic Surfaces." In 2021 IEEE Sensors. IEEE, 2021. http://dx.doi.org/10.1109/sensors47087.2021.9639542.

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Ottermann, Rico, Shuowen Zhang, Berend Denkena, Heinrich Klemme, Dennis Kowalke, Michael Korbacher, Folke Dencker, and Marc Christopher Wurz. "In Situ Resistance Trimming of Directly Deposited Thin-Film Strain Gauges." In 2022 IEEE Sensors. IEEE, 2022. http://dx.doi.org/10.1109/sensors52175.2022.9967357.

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Lei, Jih-Fen, Lisa C. Martin, and Herbert A. Will. "Advances in Thin Film Sensor Technologies for Engine Applications." In ASME 1997 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/97-gt-458.

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Advanced thin film sensor techniques that can provide accurate surface strain and temperature measurements are being developed at NASA Lewis Research Center. These sensors are needed to provide minimally intrusive characterization of advanced materials (such as ceramics and composites) and structures (such as components for Space Shuttle Main Engine, High Speed Civil Transport, Advanced Subsonic Transports and General Aviation Aircraft) in hostile, high-temperature environments, and for validation of design codes. This paper presents two advanced thin film sensor technologies: strain gauges and thermocouples. These sensors are sputter deposited directly onto the test articles and are only a few micrometers thick; the surface of the test article is not structurally altered and there is minimal disturbance of the gas flow over the surface. The strain gauges are palladium-13% chromium based and the thermocouples are platinum-13% rhodium vs. platinum. The fabrication techniques of these thin film sensors in a class 1000 cleanroom at the NASA Lewis Research Center are described. Their demonstration on a variety of engine materials, including superalloys, ceramics and advanced ceramic matrix composites, in several hostile, high-temperature test environments are discussed.
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Ottermann, Rico, Daniel Klaas, Folke Dencker, Marc Christopher Wurz, Dominik Hoheisel, Peter Rottengatter, and Thomas Kruspe. "Direct Deposition of Thin-Film Strain Gauges with a New Coating System for Elevated Temperatures." In 2020 IEEE SENSORS. IEEE, 2020. http://dx.doi.org/10.1109/sensors47125.2020.9278661.

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Suttmann, Oliver, Ulrich Klug, and Rainer Kling. "On the damage behaviour of Al 2 O 3 insulating layers in thin film systems for the fabrication of sputtered strain gauges." In SPIE LASE, edited by Alexander Heisterkamp, Joseph Neev, and Stefan Nolte. SPIE, 2011. http://dx.doi.org/10.1117/12.876134.

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Datta, Arindom, Hongseok Choi, and Xiaochun Li. "A Novel Batch Production Technique of Metal Embedded Thin Film Microsensors for Applications in Manufacturing." In ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-81211.

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Effective monitoring and diagnosis of manufacturing processes is of importance in reducing operation costs, improving product quality, and reducing process time. If conditions of manufacturing tools are continuously monitored, problems can be detected and solved during the processing cycle, resulting in less tool damage, higher productivity, and less energy consumption. In-situ monitoring of the basic operating conditions (e.g. temperature and strain) of certain mechanical tools and components can be accomplished by placing microsensors in some critical locations. Thin film microsensors (e.g. thermocouple, strain gauge) have drawn considerable attention recently due to their small size, fast response and lower cost [1]. Since most tools and components in manufacturing process are metallic, metal embedded thin film microsensors are very attractive. A new batch fabrication technique based on electroplating and wet chemical etching of silicon has been developed. Microsensors were directly fabricated on an etch stop layer grown on silicon wafer. A multilayer dielectric is deposited to insulate sensor areas followed by seed layer deposition, and electroplating a thicker metal layer. After silicon wafer is etched out, the microsensors are transferred from silicon to electroplated metal substrate directly. After plasma etching of the etch stop layer, these sensors can be further embedded into another electroplated metal layer from the top after insulation by dielectric multilayer. Metal embedded strain gauge array was fabricated successfully. Thin film Ni/Cr strain gauges were fabricated on LPCVD silicon nitride layer grown on a 3-inch silicon wafer. Each strain gauge unit was insulated by Al2O3/PECVD SixNy/Al2O3 multilayer before seed layer deposition and electroplating a thick nickel layer on whole wafer. Si wafer was then etched out in KOH solution to transfer all microsensors to electroplated nickel layer. LPCVD nitride layer covering the sensors was dry etched and same multilayer dielectric was selectively deposited over the sensors except pad areas. These microsensors were finally embedded into another electroplated nickel layer leaving the pads uncovered for external connection. This process offers a novel way to realize batch production of metal embedded microsensors for use in hostile manufacturing environment.
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Anderson, Justin S., and Jerry G. Rose. "In-Situ Test Measurement Techniques Within Railway Track Structures." In IEEE/ASME/ASCE 2008 Joint Rail Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/jrc2008-63047.

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Recent changes in national transportation needs have placed increased burden on railroad infrastructure. To meet the increased demand for efficient freight transport, the railroad industry has increased traffic volume and maximized axle loadings. Increased axle loads have forced railroads to reevaluate existing infrastructure to ensure their ability to accommodate the additional traffic loads. It is imperative to design and maintain tracks such that they can withstand high volume and increasing axle loads over an extended service life, considering the track structure is the most significant capital expense for railroad companies. It has been desirable for years to develop non-intrusive procedures to directly measure pressures and stresses at various levels and interfaces in the railroad track structure in order to optimize track designs and improve subsequent track performance. Methods for measuring both pressures and deflections have been presented in recent research focusing on assessing the performance of trackbeds with increased track modulus, primarily through the addition of asphalt underlayment. These studies involve instrumenting HMA trackbeds with earth pressure cells and displacement transducers to measure pressure levels and distributions within the track structure and rail deflections under moving trains. Additional test methodologies have been developed to include pressure readings at interfaces like the rail/tieplate interface and the tieplate/tie interface using very thin pressure sensitive Tekscan sensors. The Tekscan Measurement System uses a piezoelectric film sensor composed of a matrix-based array of force sensitive cells, similar to mini strain gauges, to obtain accurate pressure distributions between two surfaces in the track. The procedure appears applicable for a wide variety of specific track related measurements to include: 1) analyzing pressure distribution patterns at the rail base/tie plate/tie interfaces to minimize wear and eliminate pressure points, 2) validating and optimizing horizontal curve geometric design criteria relative to superelevation, 3) assessing crossing diamond, other special trackwork, and bridge approach impact pressures, and 4) evaluating the advantages/disadvantages of various types of tie plates, fastenings, and tie compositions with the objective of equalizing pressure distributions over the interface areas. Results of testing are presented in detail for test installations on CSX Transportation heavy tonnage mainlines and at the Transportation Technology Center (Pueblo) low track modulus heavy tonnage test track.
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