Research On Fast Drunk-driving Detection Method Based On Bio-impedance Spectroscopy Measurement

Blood alcohol concentration(BAC)is the main evidencce of drunk-driving detection(DDD).The existing BAC detection methods include blood test,breath test,near-infrared spectroscopy,laser method,etc,but they have various deficiencies.As a non-invasive,portable,and fast measurement technology,bio impedance spectroscopy(BIS)cacn o btain the physiological and pathological status of living body by detecting the bioimp edance-frequecy changing law of biological tissue.This thesis exploratorily pro poses a novel DDD method based on BIS measurement,and attempts to verify the feasibility of BAC prediction through BIS data.The main contents of this thesis are as follows:(1)The development of BAC detection and bio-impedance technology were introducled.meanwhile,the mechanisms of alcohol on the human body were studied,including fluence of alcohol on ion channels,blood and blood vessels,which provided a theoretical foundation for BAC detection based on BIS.(2)A fast DDD instrument based on BIS measurement was designed,which in.jects excitation signal of multiple frequency sine(Multisine)into human arms,and acqures BIS amplitude-frequency and phase-frequency characteristics of subjects after FFT processing on response signal and excitation signal.The seven modules of this instrument were analyzed in detail,including FPGA controlling module,the excitation signal generating module,4-electrode measurement front-end,signal acquisition module,SRAM cache module,STM32 controlling module,and power supply module.(3)Experiments were conducted by using the desinged instrument.First,repetitive experiment,maximum magnitude root mean square(RMS)error of 2.58? and the maximum phase RMS error of 0.19° were obtained by 10 measurements on the same subject:Secondly,interference factor ex periments,the impacts of drinking water and doing exercise on bio-impedance measuring results were exclued;Finally,alcohol drinking experiment,BIS and BAC of eight subjects drinking alcohol were measured,in which BIS were measured by body composition analyzer SFB7 and the designed instrument,and BAC were measured by breath alcohol detector AT08(4)Measurement results were processed.First,Cole module fitting was programed to fit results of SFB7 and the designed instrument separately,and it was found that the curves of fitting parameters R0 and R? were similar with the obtained BAC curve,which verified the feasibility of BAC detection based on BIS measurement;Secondly,partial least squares(PLS)method was applied to predict unknown BAC of subjects by BIS.Then a module inside subjedct and a moduel between subjects were built.In the former module,SMREC of calibration samples was 4.26,correlation coefficient R=0.9,and the SMREP of prediction samples was 9.12;In the latter module,SMREC=3.94,R=0.99,SMREP=9.35.The feasibility of quantitative fast detection of BAC based on BIS was verified preliminarily through experiments,and the theoretical and practical basis were provided for further study on fast DDD by using BIS technology.