DermaBridge: A Novel Mixed-Signal System for Electrodermal Activity Measurements With Dynamically Controlled AC Excitation

This article presents DermaBridge, an innovative adaptive mixed-signal system designed for precise measurement of electrodermal activity (EDA) using a dynamically controlled ac Wheatstone bridge tailored for driver physiological-monitoring systems in automotive scenarios. DermaBridge demonstrates high sensitivity and a wide dynamic range, with experimental results showing a relative error (RE) of less than 1% and a minimum equivalent noise conductance (ENCo) of 25 pS. The system features a 12-bit successive approximation register (SAR) analog-to-digital converter (ADC), which provides an average conductance theoretical resolution of 60.6 pS, allowing for the detection of subtle changes in skin conductance. Its real-time adaptability and accuracy are confirmed through measurements of reference resistors and physiological signals acquired with a sampling frequency of 35 Hz by the proposed system and cross validated against a certified commercial device. These measurements illustrate the system’s ability to capture both skin conductance levels (SCLs) and skin conductance responses (SCRs) under various test conditions. In addition, DermaBridge supports seamless integration with tools such as NeuroKit2 for advanced signal analysis.