Impedance Measurement System of a Biological Material Undergoing Pulsed Electric Field Exposed

This work deals with the development of an impedance measurement system for the exposure of an animal tissue (e.g. sheep muscle tissue model) to pulsed electric field (PEF). When exposed to short electric pulse, disturbances on the membrane and intra cellular components occur, modifying the behavioral response of cells exposed to foreign small materials. The phenomenon is believed to affect the electrical impedance of the tissue. While the conventional frequency based impedance measurement may reveal the electrical properties on the steady state condition, the method have been found to be insufficient for identifying impedance undergoing such very short pulse. Furthermore, this method can only take place before and after PEF. New techniques based on the pulsed voltage and current measurements have been developed for capturing the properties. The presented measurement system is composed of stainless steel electrodes that are not only designed to deliver energy to the biological tissue but also as measurement electrodes. The influence of electric field intensity of four different levels was investigated. The measured electrical impedance during pulsing was then represented to a recovery rate. The rate is defined as the changes in electrical impedance toward the electrical impedance of tissue that served as a reference of untreated tissue. The results showed that an impedance changing as a characterization of PEF level has been detected. Experiment shows that the impedance drop significantly when the PEF rise and then gradually increase regardless PEF decrease rate. A larger PEF intensity has more influence to slower down the cell membranes recovery in the tissue. The larger the PEF intensity, the slower the impedance rate.