Academic literature on the topic 'Elastic PDMS Grating'

In this paper, we propose a theoretical framework to explain how the transparent elastic grating structure can be employed to enhance the mechanical and optical properties for ultrasonic detection. Incident ultrasonic waves can compress the flexible material, where the change in thickness of the elastic film can be measured through an optical interferometer. Herein, the polydimethylsiloxane (PDMS) was employed in the design of a thin film grating pattern. The PDMS grating with the grating period shorter than the ultrasound wavelength allowed the ultrasound to be coupled into surface acoustic wave (SAW) mode. The grating gaps provided spaces for the PDMS grating to be compressed when the ultrasound illuminated on it. This grating pattern can provide an embedded thin film based optical interferometer through Fabry–Perot resonant modes. Several optical thin film-based technologies for ultrasonic detection were compared. The proposed elastic grating gave rise to higher sensitivity to ultrasonic detection than a surface plasmon resonance-based sensor, a uniform PDMS thin film, a PDMS sensor with shearing interference, and a conventional Fabry–Perot-based sensor. The PDMS grating achieved the enhancement of sensitivity up to 1.3 × 10−5 Pa−1 and figure of merit of 1.4 × 10−5 Pa−1 which were higher than those of conventional Fabry–Perot structure by 7 times and 4 times, respectively.

With the rapid development of flexible materials, various high-performance biocompatible flexible sensors have been proposed for specific measurement applications. Among these materials, polydimethylsiloxane (PDMS) is one of the most popular polymers by curing the mixture of pre-polymer (base) and cross-linker (curing agent). In this paper, a force measurement method based on PDMS grating is introduced. The PDMS grating is cast from a commercial master grating, which is precise, low-cost, and easy to follow. The elastic modulus can be controlled by the curing temperature and the mixing ratio. The PDMS grating is tested using a tension testing machine. As the stretching force increases, the grating line-spacing simultaneously increases and the diffraction light spot shifts. By capturing the light spot shift using a camera, the relationship between light spot position and stretching force is established and evaluated. Experimental results show that the linearity (R2) of the proposed method is better than 0.998, adding that the sensitivity is ~0.5–0.7N/mm and the accuracy is up to 0.05N.

In this paper, a fiber-optic liquid pressure sensor is designed and developed by encapsulating the fiber Bragg grating (FBG) inside the adjustable double-flange cylinder rigid structure with flexible polymer polydimethylsiloxane (PDMS). Within the elastic deformation range of the PDMS, the proposed adjustable FBG-based liquid pressure sensor is proven to change its measuring range while maintaining high measurement sensitivity by simply adjusting the structure, that is, the sensor can achieve high measurement sensitivity in various liquid levels. In addition, the simulation and experimental results show that the sensor sensitivity can be enhanced by the proper changes of the structural parameters, such as the inner diameter, etc. The proposed sensor has shown that it has good linearity and stability, which provides a new opportunity for the monitoring of liquid pressure in oceans, dams and other environments.

Aiming at the problems of lateral force interference and non-uniform strain of robot fingers in the process of pressure tactile sensing, a flexible tactile sensor with a square hole structure based on fiber Bragg grating (FBG) is proposed in this paper. Firstly, the optimal embedding depth of the FBG in the sensor matrix model was determined by finite element simulation. Secondly, according to the size of the finger knuckle and the simulation analysis based on the pressure tactile sensor element for the robot finger, the square hole structure was designed, and the overall dimensions of the sensing element and size of the square hole were determined. Thirdly, the FBG was embedded in the polydimethylsiloxane (PDMS) elastic matrix to make a sensor model, and the tactile sensor was fabricated. Finally, the FBG pressure tactile sensing system platform was built by using optical fiber sensing technology, and the experiment of the FBG tactile sensor was completed through the sensing system platform. Experimental results show that the tactile sensor designed in this paper has good repeatability and creep resistance. The sensitivity is 8.85 pm/N, and the resolution is 0.2 N. The loading sensitivity based on the robot finger is 27.3 pm/N, the goodness of fit is 0.996, and the average value of interference in the sensing process is 7.63%, which is lower than the solid structure sensor. These results verify that the sensor can effectively reduce the lateral force interference and solve the problem of non-uniform strain and has high fit with fingers, which has a certain application value for the research of robot pressure tactile intelligent perception.

Aiming at the problem of flexible sliding tactile sensing for the actual grasp of intelligent robot fingers, a double-layer sliding tactile sensor based on fiber Bragg grating (FBG) for robot fingers is proposed in this paper. Firstly, the optimal embedding depth range of FBG in the elastic matrix of polydimethylsiloxane (PDMS) was determined through finite element analysis and static detection experiments of finger tactile sensing. Secondly, the sensor structure is optimized and designed through the simulation and dynamic experiments of sliding sensing to determine the final array structure. Thirdly, the sensing array is actually pasted on the surface of the robot finger and the sensing characteristics testing platform is built to test and analyze the basic performance of the sliding tactile sensor. Then, the sensor array is actually attached to the finger surface of the robot and the sensing characteristics testing platform is built to experiment and analyze the basic performance of the sliding tactile sensor. Finally, a sliding tactile sensing experiment of robot finger grasping is conducted. The experimental results show that the sliding tactile sensor designed in this paper has good repeatability and creep resistance, with sensitivities of 12.4 pm/N, 11.6 pm/N, and 14.5 pm/N, respectively, and the overall deviation is controlled within 5 pm. Meanwhile, it can effectively sense the signals of the robot fingers during static contact and sliding. The sensor has a high degree of fit with the robot finger structure, and has certain application value for the perception of sliding tactile signals in the object grasping of intelligent robot objects.

Abstract Wavelength-tunable organic semiconductor lasers based on mechanically stretchable polydimethylsiloxane (PDMS) gratings were developed. The intrinsic stretchability of PDMS was explored to modulate the period of the distributed feedback gratings for fine tuning the lasing wavelength. Notably, elastic lasers based on three typical light-emitting molecules show comparable lasing threshold values analogous to rigid devices and a continuous wavelength tunability of about 10 nm by mechanical stretching. In addition, the stretchability provides a simple solution for dynamically tuning the lasing wavelength in a spectral range that is challenging to achieve for inorganic counterparts. Our work has provided a simple and efficient method of fabricating tunable organic lasers that depend on stretchable distributed feedback gratings, demonstrating a significant step in the advancement of flexible organic optoelectronic devices.

We report the mechanical control of plasmonic coupling between gold nanoparticles (GNPs) coated onto a large area wrinkled surface of an elastomeric template. Self-assembly and bottom-up procedures, were used to fabricate the sample and to increase the size of GNPs by exploiting the reduction of HAuCl4 with hydroxylamine. The elastic properties of template, the increase of nanostructure size joined with the particular grating configuration of the surface have been exploited to trigger and handle the coupling processes between the nanoparticles. Full Text: PDF ReferencesG. Mie, "Beiträge zur Optik trüber Medien, speziell kolloidaler Metallösungen", Ann. Phys. 25, 377 (1908) CrossRef U. Kreibig and M. Vollmer, Optical properties of metal cluster, Berlin 1995 CrossRef S. A. Maier, Plasmonics: Fundamentals and Applications, Springer, New York, 2007 CrossRef L. A. Lane, X. Qian, and S. Nie, "SERS Nanoparticles in Medicine: From Label-Free Detection to Spectroscopic Tagging", Chem. 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Optical beam-steering is becoming a key optical functionality in free space optical links used for communication and sensing. For example, in recent times, compact, wide-angle, fast, multi-axis beam steering is used extensively for LiDAR system in automotive vehicles, remote sensing platforms and deep-space optical communication. The state-of-the-art beam steering optics are typically based on mechanical, optical and/or electronic array designs. The present work investigates alternate schemes to perform multi-axis beam steering using one-dimensional diffraction gratings. Various schemes to perform multi-axis steering utilizing spectral scanning, pitch tuning and grating azimuthal rotation are discussed. More specifically, rigid silicon nitride gratings on glass substrate are designed for polarization-independent, spectrally scanned steering. The silicon nitride structures are optimized to achieve high diffraction efficiency for both linear polarizations by interfacing MATLAB based Genetic Algorithm Optimization and Lumerical FDTD based optical simulations. The dynamic steering is studied by varying the wavelength of incidence beam and azimuthal rotation of the grating about the normal to the grating. In diffraction gratings, the change in wavelength has the same effect as the change in pitch of the grating. Thereby flexible silicone material, Polydimethylsiloxane (PDMS) based grating is designed and optimized for polarization insensitive, high diffraction efficiency into a particular order and simulated for pitch tuning and azimuthal rotation. Lastly, experimental study of multi-axis beam steering using glass blazed gratings by incorporating spectral scanning and azimuthal rotation is discussed.