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In recent years, wearable flexible sensors have garnered significant attention for their potential in monitoring human physiological signals. Current research focuses on flexible sensors with a wide linear range, high sensitivity, and excellent reliability. Micronanostructures have been introduced to balance these three features to some extent. Inspired by the micronanostructures of human fingerprints, we propose a fingerprint-like flexible sensor that combines polydimethylsiloxane with a grating structure and laser-induced graphene. This fingerprint-like flexible sensor exhibits several desirable characteristics: a wider linear range (0-180°), faster response time (0.3 s), higher sensitivity (688.5 kPa-1), and excellent reliability (>10,000 cycles). These features make fingerprint-like flexible sensors particularly suitable for detecting various human physiological signals, including finger flexion, elbow flexion, finger pressure, and pulse. Therefore, there is considerable potential for integrating multiple fingerprint-like sensors into human physiological signal monitoring applications. This approach offers a promising direction for the future development of wearable flexible sensors. [ABSTRACT FROM AUTHOR]

Irradiation of polymer films by a CO2 infrared laser under ambient conditions converts the polymer into porous graphene or laser-induced graphene (LIG). Here, we simulate the formation of LIG from five different commercially available polymers using reactive molecular dynamics. We determined that the molecular structure of the parent polymer has a significant effect on the final graphitic structure. CO is liberated during the initial part of the LIG formation process when the polymer is converted into an amorphous structure, while H2 is evolved steadily as the amorphous structure is converted to an ordered graphitic structure. The LIG structure has out-of-plane undulations and bends due to a significant number of 5- and 7-member carbon rings present throughout the structure. We find that the simulated molecular structure compares well with recent experimental observations from the literature. We also demonstrate that the yield of LIG is higher in inert conditions, compared to environments with oxygen. Polybenzimidazole-derived LIG has the highest surface area and yield among the five polymers examined. These findings provide knowledge of LIG formation mechanisms that can be leveraged for bulk LIG applications such as sensors, electrocatalysts, microfluidics, and targeted heating for welding polymers. [ABSTRACT FROM AUTHOR]