Optical Diffraction Strain Sensor Prepared by Interference Lithography

Abstract

An optical strain sensor was developed for use in stretchable electronics. It consists of a diffraction grating formed directly on the examined surface illuminated by a laser beam which creates interference pattern. This pattern can then be used to determine axial and lateral strains for a uniaxial stress states. Direct laser interference patterning was employed as a fast processing tool for the preparation of micro-and sub-microgratings. Two coherent beams of Nd:YAG laser with 532 nm wavelength and pulse duration of 10 ns were used to selectively remove material from the irradiated sample surface. This technique creates periodic pattern on the metallized surface of polymeric substrates. New sensors formed by direct laser interference patterning method were able to resolve higher order diffraction maxima, which would be of benefit for strain measurement application. Experimental setup for tensile tests was composed of laser probe, the sensor element, and CCD camera. To extract strain values, we analysed acquired interference pattern images in real time software, developed with LabVIEW environment. This kind of contactless strain sensor is suitable for examination of stretchable electronics component for which conventional tensile tests are either not acceptable or can interfere with its normal operation.

Magnetotransport Properties of Semi-Metallic Bismuth Thin Films for Flexible Sensor Applications

“…Coatings 2021, 11, x FOR PEER REVIEW 2 of 10 structures and their magnetotransport properties is expanding fast [18][19][20][21][22]. Bi films can be fabricated by various techniques such as liquid-based exfoliation [23,24], molecular beam epitaxy [25], and acid intercalated exfoliation [26].…”

“…Thin layers and nanostructures of bismuth offer also a very high magnetoresistance, reaching even 380,000% at low temperatures [17]. These properties make bismuth a good candidate for the use in sensors, and the literature devoted to the fabrication of low dimensional Bi structures and their magnetotransport properties is expanding fast [18][19][20][21][22]. Bi films can be fabricated by various techniques such as liquid-based exfoliation [23,24], molecular beam epitaxy [25], and acid intercalated exfoliation [26].…”