ABSTRACT
This chapter focuses on the sensor mechanism. Theoretical modeling on the sensor transducer gain and the fundamental sensor noise floor is demonstrated to yield the sensor signal-to-noise ratio (SNR). The chapter presents the line-width narrowing effect to justify the advantage of oscillator-based frequency-shift detection. It demonstrates the design optimization to maximize the sensor SNR under various practical implementation constraints. The chapter also demonstrates an eight-cell frequency-shift-based sensor array realized in a 130 nm complementary metal oxide semiconductor (CMOS) process. It presents the measurement results of the sensor system for both electrical performance and magnetic sensing. Future point-of-care molecular-level diagnostic systems require advanced biosensors that can offer high sensitivity, ultraportability, and a low price tag. Sensor Design Scaling Law discusses the theoretically derived SNR expression enables sensor design optimization. Multiplexers and buffer amplifiers together with distribution lines deliver the output signals from the selected sensor cells to a down-conversion block.
