Memcapacitance in human skin : Design of a measuring system to investigate memcapacitive effects in the stratum corneum

Abstract

Memory capacitance, or memcapacitance, is part of the relative new concept of memristive systems. These are resistive, capacitive and inductive systems where their properties are dependent on previous dynamics. The purpose of this thesis is to investigate the presence of memcapacitive effects in human skin tissue. For this I have designed a measurement system utilizing LabVIEW™ for signal processing and data presentation. I have examined samples of the stratum corneum in vitro, and an arm segment in vivo, in an electrode setup. These measurements have been compared to measurements on a MOS capacitor, with known voltage dependent capacitance and hysteresis in the capacitance-voltage curve, and basic reference models and components. MATLAB simulations on mathematical electrical equivalents have been performed for further comparison. In addition capacitance- voltage characterization with a high end semiconductor characterization system was conducted on a sample of the stratum corneum, and a MOS capacitor for comparison. No strong evidence of voltage dependency or non-volatile memory was found. However, as there is a noticeable hysteresis in the charge-voltage curve, and it is between two outer plates in the form of the electrodes, skin do fall under the term memristive systems.