5th International Conference on Materials Science and Nanotechnology For Next Generation (MSNG2018), Nevşehir, Turkey, 04 October 2018 - 06 October 2019, pp.117-121
Bioelectric potentials are produced as a result of the electrochemical activity of excitable cells that are components of nervous, muscular, or glandular tissue. Biopotential electrode converts ionic currents to electrical currents at the interface between biological tissue and measurement system. In this work, combining the passive electrode with the gate terminal of depletion type n-MOSFET is proposed as a new approach to biopotential sensing. Due to the depletion type transistor characteristic, the channel between the drain and the source is open and current flows even though there is no voltage at the gate terminal. Thus, when an electrode is attached to the skin surface, the gate terminal senses the biopotential signal. Oscillations, depending on the sensed signal, occurs on the current flowing
through the source to drain. Drain and source terminals of several transistors in the proposed method are electrically connected among themselves. Thereby, biopotential signals from different regions of the skin surface are summed and transformed into drain current by the use of MOSFETs. Furthermore, at low frequencies, gate terminal of MOSFET exhibits too high impedance to affect the measured biopotential signal and makes isolation between human skin and measurement system. The obtained characteristic I-V curve of the transistor suggests that the proposed design can be used for the sensing of biopotentials.