Light-Addressable Electrochemical Sensors toward Spatially Resolved Biosensing and Imaging Applications

The light-addressable electrochemical sensor (LAES) is a recently emerged bioanalysis technique combining electrochemistry with the photoelectric effect in a semiconductor. In an LAES, a semiconductor substrate is illuminated locally to generate charge carriers in a well-defined area, thereby confining the electrochemical process to a target site. Benefiting from the unique light addressability, an LAES can not only detect multiple analytes in parallel within a single sensor plate but also act as a bio(chemical) imaging sensor to visualize the two-dimensional distribution of specific analytes. An LAES usually has three working modes: a potentiometric mode using light-addressable potentiometric sensors (LAPS) and an impedance mode using scanning photoinduced impedance microscopy (SPIM), while an amperometric mode refers to light-addressable electrochemistry (LAE) and photoelectrochemical (PEC) sensing. In this review, we describe the detection principles of each mode of LAESs and the concept of light addressability. In addition, we highlight the recent progress and advance of LAESs in spatial resolution, sensor system design, multiplexed detection, and bio(chemical) imaging applications. An outlook on current research challenges and future prospects is also presented.