Semiconductor-based sensors for imaging of chemical processes

To study chemical and biological processes, the spatially resolved determination of concentrations of one or more analyte species is of distinct interest. With a light-addressable potentiometric sensor (LAPS) chemical images can be created, which illustrate the concentration distribution on the sensor chip. LAPS belongs to the family of semiconductor-based potentiometric (bio-)chemical sensors. With the help of a modulated and focused light source, a photocurrent is generated that depends on the local concentration on the sensor surface. By scanning the light source along the sensor plane the concentration distribution can be determined. In this study, different LAPS set-ups are presented and compared. A scanning LAPS with a single laser diode moved by piezoelectric motors, a digital mirror device (DMD)-based LAPS utilising a video projector, and an organic light-emitting diode (OLED)-based LAPS.