A Pixeless, Leadless Photoelectrochemical System for High Spatiotemporal Biosensing

Microelectrodes and transistor-based biochemical sensors have paved the way for high-sensitivity electrical and electrochemical sensing of entities like reactive oxygen species (ROS), inflammatory cytokines, and metabolites. Yet, achieving leadless high spatiotemporal sensing remains a challenge due to the technical intricacies and spatial restrictions associated with micropatterned arrays. In this work, we introduce a leadless approach for photoelectrochemical sensing leveraging the plasmonic nanostructured Au-TiO2 systems. These systems are characterized by their efficient light-to-current conversion capabilities, offering precise high spatiotemporal photocurrent mapping. Notably, our method facilitates the quantification of chemical concentrations in randomly defined regions-of-interest and provides a detailed profile of biochemical distributions via photoelectrochemical mapping. Additionally, we showcase the potential of bionic imaging on the pixelless device with micrometer resolution, reconstructing light-generated patterns with multimodal information including position, intensity, and color. The monolithic system can also be made on flexible substrates to enable tissue-level photoelectrochemical sensing in vivo.