Light-addressable potentiometric sensor with the micro blind holes substrate

The light-addressable potentiometric sensor (LAPS) is one sort of biochemical sensor based on semiconductor principle. To improve the performance of LAPS, a novel designed silicon substrate with micro blind holes structure used for LAPS is presented in this study. In this structure, a great number of micro blind holes are constructed on the back surface of substrate by silicon wet etching technology. When light illuminating the bottom of substrate, because of the light trapping effect, multiple reflection on surface of substrate increases the absorption of light, which will remarkably enhance the photoelectric conversion efficiency. In this research, LAPS chips with 300 mu m thick substrate, 270 mu m thick substrate, 200 mu m thick substrate, and micro blind holes substrate were constructed. The performance of these LAPS, such as amplitude of photocurrent, sensitivity, linearity, signal to noise ratio (SNR) were evaluated, and the results showed that, constructing micro blind holes structure on back surface of substrate illuminated by light can remarkably increase the amplitude of photocurrent, sensitivity, linearity and SNR, and additionally maintain the mechanical strength of substrate, which means the structure is an effective way to improve performance of LAPS.