| Pressure ulcers are chronic skin wounds with a particularly high morbidity and a long treatment period,which puts tremendous pressure on the national medical security system and patients.Currently there is no technique or real-time monitoring system that can realize the detection of pressure ulcers.Electrical Impedance Tomography(EIT)is a non-invasive,safe and non-radiation visualization technique that uses electrical signals as a carrier.It can reconstruct the distribution of electrical impedance according to the impedance changes of the measured object at different time or frequency points.This thesis is based on electrical impedance tomography technique to achieve twodimensional visual imaging and one-dimensional impedance spectroscopy measurement of the pressure ulcer area.Combining the two detection results to improve the measurement accuracy of electrical impedance of the pressure ulcer,so as to realize the accurate identification of the pressure ulcer area.The following main research work has been carried out.(1)A detection system of pressure ulcer,including the flexible electrode sensor array,EIT hardware system and pressure ulcer imaging software,has been designed and implemented.The design of the flexible electrode sensor has been optimized from the sensor substrate material and spatial configuration mode.EIT hardware system implemented can realize the measurement of impedance and impedance spectroscopy of the measured object;the pressure ulcers imaging software can realize the real-time visualization and processing of the data,achieving the function of real-time monitoring.(2)Numerical simulation and agar tissue-mimicking phantoms experiment has been designed and carried out.According to the human skin tissue structure,singletissue and multi-tissue stratification experiments were designed respectively.In each set of numerical simulation and phantom model experiments,the image reconstruction results of simulated pressure ulcers with different locations and different depths in the measured area were discussed and compared,and the feasibility of the pressure ulcer detection system for pressure ulcer detection was preliminarily verified.(3)In vivo rat pressure ulcer experiments have been designed and carried out.By exerting continuous pressure with different time lengths and different amplitudes on the back of rats to produce pressure ulcers with different degrees of injury.The pressure ulcer detection system implemented has been used to detect the back of the rat,and the image reconstruction results of the pressure ulcer was obtained and compared with the actual compression position.At the same time,hydrogel electrodes are used to measure the impedance spectrum of the pressure ulcer area before and after extrusion.Combining with the EIT two-dimensional imaging results and the one-dimensional impedance spectroscopy measurement,the feasibility of applying the pressure ulcer detection system to biological tissues is verified. |
