A CMOS focal-plane-array is designed for the high-throughput analysis of enzymatic reaction in on-chip spectrophotometer system. One of potential applications of the presented prototype system is to perform enzymatic analysis of biocompounds contained in blood. This function normally requires an expensive diode-array spectrophotometer, but it is possible to perform high throughput analysis with low budget if the spectrophotometer system is scaled down to a chip. The CMOS active pixel sensor array can cover a layer of polydimethylsiloxane (PDMS) forming the microfluidic channels and the substrate solution for enzymatic reaction can be injected into the channels by capillary force. Under room light, the underneath CMOS active pixel sensor with 40 x 40 pixels detect the gray levels of the fluid’s color. Inside the image sensor chip (size: 3mm x 3mm), the pixels of the same column share the same sample and hold circuits. The analog signals from 40 columns are multiplexed into one input feeding an on-chip 8 bits dual-slope analog to digital converter. The color change can be displayed on the external monitor by using a data acquisition card and personal computer.
A novel surface plasmon resonance (SPR) sensor system using CMOS image sensor array is proposed in this paper. Recently, a simple SPR system was proposed by the author, which achieved high resolution and fast response time using a bi-cell photo-detector. However it requires mechanical adjustment process to balance two signals of the bi-cell before measurement. It requires not only additional time but also additional mechanical control unit, which is a source of the noise. It also suffers from the small linear range. The proposed method chooses a pixel as the center from many pixels, which gives the most balance of bi-cell signal. Therefore no mechanical adjustment is required. The method also overcomes the small linear range problem by switching the center adaptively during the test. Furthermore, it has several advantages of CMOS image sensor such as low cost, low power, and on-chip functionality, which makes the proposed SPR sensor system be a good candidate for field applications. A prototype CMOS image sensor chip with 12bits analog to digital converter is designed and fabricated with 0.5um AMI CMOS technology.