High Throughput Core-CBCM CMOS Capacitive Sensor for Life Science Applications

Abstract

This paper presents a throughput capacitive biosensor using charge based capacitive measurement (CBCM) technique suitable for lab-on-chip (LOC) applications. The proposed biosensor consists of a 10×10 array of core-CBCM capacitive sensors with digital outputs working in current mode. Each capacitive sensor consists of a differential current mirror, a current-controlled oscillator and an up/down counter using linear feedback shift register (LFSR). By the conversion of the current response of the core-CBCM circuit to pulse frequencies and counting the number of the output pulses during a specific time interval, we can do the required integration in the digital domain instead of the analog domain and thus prevent operation in voltage mode. This approach helps to obtain a wide dynamic range more than 100fF (about 80 dB) with a controllable sensitivity about 118 pulse/fF. Based on the simulated results, the proposed sensor offers great advantages for high throughput drug screening applications.