The water transfer printing method is used to transfer patterned films on random three-dimensional objects. This industrially viable technology has been demonstrated to intimately wrap metallic and polymeric films around different materials. This method avoids the use of rigid substrate during the transfer step. Patterns can be transferred to objects without folds even when holed, addressing a challenging issue in the field of conformal electronics. This technique allows high film bending properties to be reached. This promising method enables us to integrate large-area films onto daily life objects. A bent capacitive touchpad is fabricated showing the potential applications of this technology.
New materials and optimized fabrication techniques have led to steady evolution in large area electronics, yet significant advances come only with new approaches to fundamental device design. The multimodal thin‐film transistor introduced here offers broad functionality resulting from separate control of charge injection and transport, essentially using distinct regions of the active material layer for two complementary device functions, and is material agnostic. The initial implementation uses mature processes to focus on the device's fundamental benefits. A tenfold increase in switching speed, linear input–output dependence, and tolerance to process variations enable low‐distortion amplifiers and signal converters with reduced complexity. Floating gate designs eliminate deleterious drain voltage coupling for superior analog memory or computing. This versatile device introduces major new opportunities for thin‐film technologies, including compact circuits for integrated processing at the edge and energy‐efficient analog computation.
International audienceThis paper presents strain sensor arrays on flexible substrates able to measure local deformation induced by radii of curvature of few millimeters. Sensors use n-type doped microcrystalline silicon (μc-Si) as piezoresistive material, directly deposited on polyimide sheets at 165 °C. Sensitivity of individual sensors was investigated under tensile and compressive bending at various radii of curvature, down to 5 mm. A Transmission Line Method was used to extract the resistivity for each radius. The devices exhibited longitudinal gauge factors of −31 and longitudinal piezoresistive coefficients of −4.10−10 Pa−1. Reliability was demonstrated with almost unchanged resistances after cycles of bending (standard deviation of 1.7%). Strain gauge arrays, composed of 800 resistors on a 2 cm2 area, were fabricated with a spatial resolution of 500 × 500 μm2. Strain mapping showed the possibility to detect local deformation on a single resistor or to detect larger objects. These strain sensor arrays can find applications when high sensitivity and high spatial resolution is required. This paper also showed that μc-Si can be a relevant semi-conductor candidate for flexible electronic
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