Ultrathin and Flexible Organic Light‐Addressable Potentiometric Sensors

Next‐generation healthcare applications necessitate the development of flexible, tissue‐compliant bioelectronics with multi‐analyte sensing and spatially resolved imaging capabilities. Light‐addressable potentiometric sensors (LAPS) have emerged as a powerful bioelectronic device, owing to their unique light addressability which enables location‐specific sensing and imaging. However, their conventional form based on inorganic materials, such as silicon, suffers from intrinsic rigidity and low biocompatibility, which limits their further applications in soft biological interfaces. In this study, we demonstrate, for the first time, an ultrathin, mechanically compliant, fully organic light‐addressable potentiometric sensor that achieves high sensitivity to surface potentials, stable performance over 170 days, and maintains excellent flexibility as a standalone organic LAPS film for biointerface applications. By combining a donor‐acceptor bulk heterojunction organic semiconductor layer, a PEDOT:PSS transparent electrode, and a Parylene insulating layer, we demonstrate the first ultrathin organic LAPS with a thickness of 2.3–2.9 µm. We further conduct systematic evaluations to reveal the primary factors, light wavelength and insulating layer thickness, governing key performance metrics such as photocurrent sensitivity. Our newly developed flexible organic LAPS opens new avenues for further soft biointerface applications, including location‐specific electrophysiological sensing and future biochemical imaging.