Simulation And Analysis Of Human Tissue Measurement Probe Based On Spiral Resonator

As an emerging physiological signal detection method,microwave has great application prospects in the fields of medicine and biology.The electrical properties of biological tissue are inherent properties of biological tissue under the action of an external electromagnetic field.The change of the dielectric constant of biological tissue can reflect some state changes of biological tissue,so the measurement of the dielectric constant of human tissue is of great significance.Electromagnetic waves are incident into the medium of human tissue.Different dielectric constants absorb different electromagnetic waves and reflect different electromagnetic waves.The size of the reflected electromagnetic waves depends on the dielectric constant of the tissue to be measured.Therefore,the microwave probe can return electromagnetic waves according to the received electromagnetic waves.wave,which measures the dielectric constant of human tissue media.The probe used for human tissue measurement should have the following conditions:(1)high efficiency,(2)small size,(3)capable of in vivo measurement without causing damage to the tissue to be measured.In order to use microwaves to measure human body tissue in vivo and improve the resolution of the measurement,based on the antenna theory and the electromagnetic field principle,this paper combines a circular spiral resonator(SR)with a loop antenna,and designs three kinds of work at 433 MHz respectively,915 MHz and 2.45 GHz microwave probes.The main work of this thesis is as follows:(1)A small near-field probe based on a loaded spiral resonator is proposed.The simulation model of the probe is established by using HFSS electromagnetic simulation software.Simulation analysis was carried out,and the probe was impedance matched,and the value of the capacitance in the matching circuit was simulated and optimized.The probe structure with ideal performance was obtained,and three probes with operating frequencies of433 MHz,915MHz and 2.45 GHz were designed.(2)Establish a human tissue layer model under the probe,change the dielectric constant and thickness of the tissue medium,and simulate the presence or absence of nodules,and analyze the change law of the probe resonance frequency.It is concluded that the designed probe can be used for human tissue measurement.(3)The probe is verified experimentally.According to the designed probe model,the probe working at 915 MHz was made in kind,and the probe was connected to the vector network analyzer for testing.The abnormal nodules on the face were tested experimentally,and the change rule of the resonant frequency of the probe was recorded and analyzed and compared with the simulation results to verify the usability of the probe.