A multi-parameter analog-front-end circuit for liquid metal flexible sensor

Multi-parameter sensors, such as liquid metal flexible sensors, exhibit variations in resistance and capacitance in response to changes in temperature and deformation. This paper presents a multi-parameter analog-front-end (AFE) circuit designed for measuring liquid metal flexible sensors. We designed a multi-parameter interface circuit and a baseline compensation circuit to expand the types, range, and accuracy of measurements. Additionally, we integrated a 78.6 dB signal-to-noise-and-distortion ratio (SNDR) second-order fully passive noise-shaping (NS) successive approximation register (SAR) analog-to-digital converter (ADC) to achieve stable digital automated baseline compensation. The prototype was fabricated using 180 nm complementary metal oxide semiconductor (CMOS) technology, and we connected the liquid metal flexible sensor for temperature and deformation measurements. The temperature measurement range was 20 degrees C to 80 degrees C with a measurement error less than 0.34 degrees C, and the deformation measurement range was 0 mm to 6 mm with a measurement error less than 0.14 mm.