Ultra-high scanning speed chemical image sensor based on light addressable potentiometric sensor with analog micro-mirror

In chemical image sensor, spatial resolution and scanning speed are the most important factors which may need to optimize and trade off. Before the minimization of spatial resolution, scanning speed of system needs to be improved to have an image in a short time within few seconds. In this study, ultra-high scanning speed of light addressable potentiometric sensor (LAPS) could be achieved by means of the combination of laser diode and single analog micro-mirror in light source. In the constant bias operation, an U-shape of pH solution can be detected within 8.5 sec for 14×121 points in the area of 3.2 mm×6.12 mm by using 5 kHz of ac signal in laser diode. The image resolution of the present LAPS system with 10 μm-thick Si₃N₄/3 nm-thick SiO₂ on 500 μm-thick silicon wafer is 0.0116 mm² which could be further improved by LAPS structure optimization with thinner substrate. A chemical image sensor with ultra-high scanning speed is demonstrated by the application of analog micro-mirror for LAPS.