Research On The Dielectric Properties Of Non-invasive Blood Glucose Based On Split-ring Resonator

Diabetes is a major killer of human health.There is no specific method to cure it in the medical field nowadays;Blood glucose monitoring is an indispensable and important measure in comprehensive treatment of diabetes.When using the commercial blood glucose monitors available on the market,patients not only run the risk of blood infection,which worsens their medical conditions,they are also reluctant to be monitored due their fear of the pain,thus making the blood glucose collection much more difficult.Non-invasive blood glucose came into being against his background in recent years,which can not only meet the needs of doctors for professional auxiliary treatment,but also reduce patient's fear and promote treatment.Non-invasive blood glucose technology based on microwave detection has become a new research hotspot.There are several problems in these researches at present:1.There are few experiments on the human body.Solutions with different glucose concentrations are mainly used in the research.However,due to the large difference between the glucose solution and human blood,the accuracy of the study is affected;2.The parameters for analysis are relatively single and un-diverse,and they carry less physiological and pathological information;3.The experimental research only analyzes the collected data,ignoring individual differences,and has no universal applicability.Aiming at the above problems,this paper mainly studies the feasibility of non-invasive blood glucose monitoring at the frequency of 1.15 GHz,and has carried out the following work:(1)Based on the microwave radio frequency theory and the principle of blood glucose monitoring in a resonant cavity,a system for collecting dielectric characteristics of blood glucose in the human abdomen based on a split ring resonant cavity structure was designed.The structure and parameters of the split-ring resonator are optimized.The resonance frequency of this system is 1.15GHz,and non-invasive blood glucose dielectric constant measurement can be realized.(2)The dielectric characteristics and measurement principles of biological tissues are analyzed.The dielectric characteristics were simulated based on human abdomen biological models with different fat layer thickness and blood glucose changes,and three parameters estimating the dielectric characteristics have been proposed:the resonance frequency and 3d B bandwidth of the forward transmission coefficient's(S₂₁),and the thickness of the fat layer.(3)A single parameter(S₂₁'s 3d B bandwidth)and a multi-parameter linear regression algorithm based on the three parameters ofS₂₁'s resonance frequency,3d B bandwidth,and fat layer thickness are proposed.The multi-parameter blood glucose dielectric characteristics estimation method based on Gaussian process regression and neural network regression model is proposed based on the analysis above.It is verified by simulation experiments that all three methods can complete the regression calculation under complex conditions of the blood glucose dielectric constant,and achieve high-precision continuous blood glucose dielectric monitoring.Among them,the model based on Gaussian process regression does not require prior conditions and has better performance.(4)Experiments on pork glucose injection and oral glucose tolerance test under different fat layer thickness conditions are conducted by means of the split-ring resonant cavity blood glucose dielectric property measurement system.The actual test results show that the accuracy of the dielectric constant measurement of the pork glucose injection experiment is around 99%;The accuracy of the human glucose tolerance experiment is over 81%.The experimental results verify the accuracy of the system and provide a basis for further searching for the relationship between the dielectric properties of the human abdomen and the blood glucose concentration,thus laying foundation for realizing the non-invasive blood glucose monitoring.