Simulation Analysis And Experimental Research Of Minimally Invasive Bio-Electrical Impedance Measurement

Bioelectrical impedance technology is a detection technology which extracts biomedical information using the electrical characters of biological tissue and organs and their changes. The technology is non-invasive/micro-invasive, inexpensive and capable of reflecting information of function. Especially the technology can detect the changes of electrical properties of body tissue before the construction of cells and tissue change, by extracting information from biological information. It's significant for diagnosis of cancer in early stage in clinical medicine. Surface electrodes are used generally to measure bio-impedance. There is large contact resistance and uncertainty between the surface electrodes and skin. Also AC interference would be easily introduced, which could affect the effective extraction of useful information and image resolution of the follow system. Therefore, electrode system is crucial to bioelectrical impedance measurement and follow imaging quality.In this paper, with the microelectrode technology, the micro-needles were applied as the excitation electrodes in the impedance measurement system. Minimally invasive sensitivity measurement and accurate extraction of useful information were achieved. The micro-needles can pass through the stratum corneum and reach the dermal tissue which could be considered as electrolyte because of its dimensional characteristics. Based on the basic theory of bioelectrical impedance electromagnetic fields,2D/3D models were built by finite element analysis software in this paper. Much simulation analysis and experimental research, including the comparison between the effect of different electrode contact mode, the different contact area between electrodes and tissue, the influence of different tumor size and the different location of tumor infiltration have been done. It is concluded that minimally invasive method of electric impedance measurement can obtain more accurate internal information, and enhance the sensitivity. The method could achieve early diagnosis specifically for superficial cancer such as breast cancer and skin cancer. Additionally, the exploratory studies on the thermal effect of electrode and the electrical signals stimulation to the tumor cell in minimally invasive measurement were done, which was meaningful for clinical application by providing experimental and simulation data. A new method with sensitizers for bio-electrical impedance minimally invasive sensitive measurement was designed and developed to enhance the impedance contrast ratio between tumor and healthy tissue in this paper. Necessary simulation and experiments to verify the effectiveness of sensitizer were implemented. The nano-particles were demonstrated to have obvious sensitive effect on the electrical impedance measurement.