A low-power bio-sensor interface with wide measurement range

A new low-power high dynamic range conductanceto- frequency converter, using relaxation oscillator approach, is proposed for bio-sensor interfacing applications. Enhanced by a leakage current compensation technique, the interface has immunity against input pad ESD leakage current as well as hum noise. The output frequency is linear with respect to sensor conductance, with the maximum systematic error of 0.58% and average error of 0.46% for nanowire sensor resistance from 100 MΩ ~ 1 GΩ. For 2% systematic error, the resistance range of the interfacing system can attain from 5 MΩ to 5 GΩ. The biosensor interface is designed using CSM 0.18 μm CMOS technology, which dissipates 37.2 μW at a single supply of 1.8V and the maximum sensor current.Published versio