Design and Validation of Front-End Voltage Follower for Capacitive Electrocardiogram Measurement Using Bootstrapping Technique

We addressed design of bootstrapped voltage follower (BVF) in analytical approach from a perspective of capacitive electrocardiogram (cECG) measurement. Theoretical formulas of transfer function, resonant frequency and damping ratio for BVF were derived and experimentally validated. The transfer function and resonant frequency were beneficial for predicting cutoff frequency and frequency-gain characteristics of attenuation band in the low-frequency region. The damping ratio was beneficial for foreseeing occurrences of resonance and distortion in cECG recording. Next challenge is to derive an index inferring settling time after contamination of movement artifact, and to evaluate it experimentally.