Development Of Thermal Response Measuring System For Assessing Blood Perfusion In Microcirculation

The common methods for assessing superficial blood perfusion are based on the Doppler effect,interference or plethysmography,which are often inadequate due to the limitation of their site dependence.Thermal response analysis shows its potential in the perfusion assessment since it is low-cost,rich in information and the result can be compared site-to-site.A novel device with flexible film,where 5 high-accuracy digital temperature sensors were mounted,was invented.It was programed to control heating and measure skin temperature at12.5 samples per second.By using this device,the ability and key factors of the implement of thermal response analysis in microcirculation assessment can be researched.The data from diabetes and control group were first analysed using coarse 2-dimensional steady numerical heat transfer and line search.Average blood perfusion during rest,adapting and recovery section were compared.The two group shows agreement regrading the perfusion ratio of adapting to recovery,but diabetes group has lower ratios in general,stating that diabetes tend to recover slower from local heating.Extra considerations must be taken when a transient inverse heat transfer problem is involved,for it is severely ill-posed.Techniques such as compiler optimization and parallel were applied to overcome the increased computational needs.And experiment errors were estimated and reduced to overcome the sensitivity of inverse problem.Using a frame combined numerical heat transfer and parameter optimization,the thermal properties of flexible film were estimated by the experiment data which involved in the thermal interaction between film and a water bag.It was found that fit thermal model and proper optimization method were essential,when assessing the temporal and spatial distribution of micocirculation with a thermal response analysis approach.Those works indicate the potential of assessing superficial blood perfusion using a thermal response analysis approach,and provide supports for further researches.