Résumé
We present a label-free biosensor capable to map local potential by photogenerating charge carriers in a field effect device. It consists in an amplitude-modulated laser beam scanning through an electrolyte/insulator/semiconductor structure at very low illumination around the equilibrium state of semiconductor. A proof of principle is demonstrated by depositing a self-assembled monolayer on the dielectric and by showing a clear photopotential change between naked and covered areas.