CMOS capactive sensor system for bacteria detection using phage organisms

The paper presents the design and implementation of a Complementary Metal-Oxide Semiconductor (CMOS) based integrated sensor system employing bacteriophage or phage organisms as recognition elements to detect deadly bacteria such as E-Coli and Salmonella. The system works on the basis of monitoring the changes in capacitance signals caused when the target bacteria get attached to the sensing interface. The system is designed using DALSA 0.8μm technology and it consists of inter-digitized capacitor structures and signal detection and processing circuitry. The signal detection and processing is done by a Charge Based Capacitance Measurement (CBCM) circuit. The phage organisms are immobilized on the surface of the capacitor and together they form the sensing interface. We achieve a sensitivity of 29.3mV/fF for the CMOS capacitive sensing interface, which corresponds to detecting infectious dose for the target bacteria. The system operates on a 5V DC supply and is estimated to consume an average power of 1.7 mW.