Research On The Characteristics Of EMT Sensors For Biological Tissues

Researching on characteristics of electromagnetic tomography sensor has great significance for biomedical imaging, detecting biological tissue conductivity which will change under different physiological conditions, improving the electromagnetic tomography system sensitivity and accuracy. So this paper conducted a study of sensor characteristics of electromagnetic tomography.Studied on the excitation sensor characteristics, established theoretical model of sensor parameters with RLC, and then derived capacitance solving equations. With the multi object field coupled finite element analysis software COMSOL, simulated the relationship between sensor parameters including (turns, radius, wire diameter) and RLC; studied the effects of sensor parameters on the spatial distribution of magnetic field; the gradient magnetic field generated by the sensor was analyzed by using matlab; calculated the eddy currents via the biological tissue generated by sensors which were applied with a amplitude and frequency current.The excitation sensor parameters are optimized based on response surface method.The detection sensor circuit model was analyzed, solved the transfer function of the system. Proposed that detection sensor should add a resistor to increase the resonance frequency and calculated the value of matching resistor. By using matlab, simulating the sensor output with different resistors; based on the coupled model of excitation and detection sensors, the influence of detection sensor parameters on the mutual inductance was analyzed.then analyzed the sensitivity of detection sensor. Simulated and analyzed the effects of the excitation and detection sensor radius matching on the sensor signal carrier ratio.The mathematical model of biological tissue eddy current distribution was derived, using simulation software COMSOL modeling the biological tissue and computing the internal eddy current contours. Analyzed the effects of biological tissue parameters including the electrical conductivity, magnetic permeability, the relative dielectric constant, the spatial position on the magnetic field generated by the excitation sensor and the output of the detection sensor. Sensitivity of the detection sensor was calculated.By making different parameter excitation and detection sensors, Verify the distribution characteristics of magnetic field strength and magnetic gradient on the optimized excitation coil, verify the output characteristics of the detection coil with added match resistance, and experiment the different excitation and detection sensors to verify the match performance. a NaCl solution with different conductivity was used to simulate brain tissue; The results showed that the optimized coil can identify small changes in the concentration of the salt solution; and the errors in the experiments were analyzed, including the detection sensor position error and shield of parameters influent output of the system, then simulated and designed the shield layer parameters in COMSOL.