In this paper we present a dual channel sensor for electrodermal activity measurement, with particular attention to the drivers' stress detection. The sensor captures the elec-trodermal signals that are present on the hands of the driver, transmits them via WiFi to a laptop and then the data are processed. In particular, we developed a novel algorithm for the removal of motion artifacts that arise when the driver moves the hands on the steering wheel. We performed several kinds of tests: first in laboratory, then on a professional driving simulator and finally in a real car in city traffic. The algorithm has been compared to several well known algorithms for signal separation. We identified, as an indicator of performances, the spectral flatness of the outputs. In this application, the proposed method outperformed the benchmark algorithms.