ABSTRACT
In future, point-of-care (PoC) molecular-level diagnostic systems require advanced biosensors that can offer high sensitivity, ultra-portability, and a low price-tag. This chapter proposes an ultrasensitive frequency-shift-based magnetic biosensing scheme that is fully compatible with standard complementary metal-oxide-semiconductor (CMOS) processes with no need for costly postprocessing steps or any electrical or permanent external biasing magnets. It focuses on the sensor mechanism. 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 signal-to-noise ratio (SNR) under various practical implementation constraints. As a design example, the chapter demonstrates an 8-cell frequency-shift-based sensor array realized in a 130 nm CMOS process. It also focuses on the system architecture and the key building blocks. The chapter also presents the measurement results of the sensor system for both electrical performance and magnetic sensing.
