A novel light-addressable potentiometric sensors set-up with LCD projector as scanning light source

In a typical set-up of light-addressable potentiometric sensor (LAPS), the individual sensing parts of the photosensitive semiconductor chip are addressed by modulated light beam such as laser beam. Although the laser can be executed with precision, the relative equipment is complex and expensive. In this work, a novel approach of utilizing Liquid Crystal Display (LCD) projector as a programmable modulated light source for LAPS set-up has been demonstrated. This setup can deliver an easy, flexible, and miniaturized light source that can address a large number of programmable measurement spots on LAPS structure. Besides, it reveals to be a very promising technique for LAPS image sensor. At present, the smallest spot size of 180 μm can be used to capture measurable signals with normal Si wafer of thickness about 550 μm. By thinning the wafer, the spot size as small as 54 μm is achieved and functions as a modulated light source in this set-up.