Study On Transdermal Extraction Of Interstitial Fluid Using Reverse Iontophoresis Assisted By Heat Permeation Effect

Diabetes,as one of the three major killers of human health,currently has no cure.It can only be used to reduce the complications of diabetes through frequent blood glucose concentration testing and insulin injection.Therefore,continuous blood glucose monitoring is of great significance.Among various existing continuous blood glucose monitoring methods,the method based on counter ion electroosmosis extraction of interstitial fluid to realize blood glucose prediction has a wide application prospect due to its low trauma,low cost,and ease of wearability.However,the biggest problem with reverse iontophoresis is that large currents are likely to cause skin irritation,and small currents cannot extract enough interstitial fluid for detection in a short time.This paper proposes a counterion electroosmosis method based on the aid of heat permeation effect,which improves the permeability of the skin by local heating,and then realizes the extraction of a sufficient amount of interstitial fluid at low current to reduce the irritation of the skin.The specific approach is to build a flexible epidermal temperature control system to achieve heating and temperature control of the skin,stimulate the skin’s heat permeability effect,and improve the extraction efficiency of interstitial fluid.Specific work includes:1.Through the comparative analysis of the existing methods of extraction of interstitial fluid,the method of assisting counter iontophoresis through thermal permeation effect is studied to achieve efficient extraction of interstitial fluid under low skin stimulation.Then,through the analysis of the skin structure and the principle of counter iontophoresis,the conjecture of the thermal permeability effect is proposed,and the principle of the thermal permeability effect is briefly analyzed.Next,the longitudinal skin impedance experiment and Na~+ extraction simulation experiment are used to verify the feasibility of the proposed thermal permeability effect-assisted counter iontophoresis method.2.Constructed a flexible epidermal temperature control system to achieve wearable thermal permeability to assist in the extraction of interstitial fluid from reverse iontophoresis,and established an arm skin model using COMSOL to explore the temperature distribution and heat dissipation of the skin surface.Then,based on the skin model,the structure simulation and parameter design of the heating wire and temperature sensor were completed,the designed heating wire and temperature sensor were processed by inkjet printing,and the performance of the finished device was tested.Designed and processed the flexible epidermal temperature control circuit,realized the software and hardware design of the proportional integral differential flexible control circuit through the AT89C51 microcontroller,and tested the performance of the processed temperature control circuit.3.Completion of the interstitial fluid extraction experiment based on the flexible epidermal temperature control system.The experiment on the extraction of interstitial fluid from the same part of the arm skin of different subjects and the different parts of the arm skin of the same subject further verified the effect of heat permeation effect to increase the extraction rate of counterion electroosmotic interstitial fluid The feasibility also reveals the potential of the constructed flexible epidermal temperature control system in wearable blood glucose monitoring devices.