Microstructure-based Direct Digital Capacitive Pressure Sensor

Abstract

Pressure sensors are important in many applications, from medical hyperbaric oxygen chambers to precision pressure monitoring in vacuum setups of semiconductor manufacturing. With their simple design and high precision, capacitive pressure sensors are one of the best designs of pressure sensors. In this thesis, we proposed a new class of microstructure-based direct digital capacitive pressure sensor, including the microstructured pressure-to-capacitance transducer and its capacitance-to-frequency digital conversion circuitry. The microstructured transducer design provides ease of fabrication and longterm durability. The novel sensor circuit using digital phase-locked-loop (PLL) enables highly sensitive detection of capacitance. For proof of concept, we fabricated the microstructured transducer and constructed the digital PLL using discrete parts. The experimental results and analysis show the viability of implementing such sensors in the future.