A CMOS-Based Phototransistor for High-Sensitivity Biochemical Detection Using Absorption Photometry

Abstract

This paper proposes a high-sensitivity biosensing system on the basis of absorption photometry and a phototransistor. Manufactured in a standard 0.35-mu m CMOS technology, the phototransistor exhibits a responsivity higher than 1000 A/W for 650-nm light. The TMB/H(2)O(2)/HRP method is chosen as a useful platform to determine the amount of various interesting targets. For the biochemical detection, a sample volume of only 10 mu l is required to be dropped on the slide above the phototransistor. Experimental results demonstrate that a high sensitivity of 2.5 mu A/pM is achieved, and the minimum HRP concentration successfully detected is 2.7 pM. This detection limit is three orders of magnitude better than that of a reported silicon biosensor.