Oscillator Based Bio-Sensor for Skin Sweating Detection: A Feasibility Survey

This paper is a feasibility survey of the design of an oscillator-based bio-sensor for skin physiological parameter detection. The sensor aims to detect stress through skin sweating measurement. The proposed architecture uses an oscillator coupled to an on-skin resonator. The oscillator is based on a cross coupled pair (CCP) which is directly connected to the resonator. The on-skin resonator has been designed to have an oscillation frequency sensitive to the sweat. Oscillator outputs are driven by two buffers that act as 50 Omega impedance matching. Two test benches, one with a dry skin and one with a wet skin, have been used for the study. The oscillation frequency of this oscillator is equal to 27.876 GHz for the dry skin, and 27.911 GHz for the wet one. The difference between the two oscillation frequencies, which is equal to 35 MHz, can be easily distinguished which validates the feasibility survey. The survey provides the sizing of each block and the simulated results in 55 nm BiCMOS technology.