Utilising Digital Micro-Mirror Device (DMD) as Scanning Light Source for Light-Addressable Potentiometric Sensors (LAPS)

The light-addressable potentiometric sensor (LAPS) is a semiconductor-based chemical sensor that utilises light beams to address individual parts of the semiconductor chip for spatially resolved measurements. The photocurrent depends on the local chemical analyte concentration. Hence, a flexible and miniaturised light source which is capable of addressing a large number of measurement spots is desired. DMD (digital micro-mirror device) is a MEMS device well known as main technology for multimedia projectors. These micro-mirror arrays are used to define hundreds of thousands of light beams in a flexible way. In this work, the authors demonstrate the usage of the DMD technology to allow the definition of thousands of measurement spots on a LAPS structure. For each measurement spot a photocurrent versus bias voltage (I/V) curve can be recorded. A shift along the horizontal axis can be evaluated and the change of the analyte concentration at the measurement spot can be determined.