Flexible Electrode Electrochemical Sensor For Determination Of Glucose And Lactate In Sweat

Diabetes is one of the major global health problems.Diabetic patients have to undergo many times of puncture blood collection everyday to determine blood glucose concentration and therefore suffer a lot.However,the sensor based on sweat glucose detection is non-invasive,and studies have shown that there is a certain correlation between sweat glucose level and blood glucose concentration.Sweat is more readily and continuously available than other body fluids and does not degrade easily.In addition to glucose,Lactate is another important compound in sweat,which is a vital clinical indicator.In the field of sports medicine,the detection of lactate is very essential.Besides,many other substances in sweat(such as ethanol,K+,Na+,Ca2+)are also closely related to human health.Therefore,thin film PET based gold electrode(PGE)sensors for the determination of glucose and lactate in sweat was studied.In chapter 1,the detection methods and classification of electrochemical biosensors,methods and materials of chemically modified electrodes and wearable sensors were reviewed.In chapter 2,flexible PGE was prepared by electroless plating,and then glucose oxidase was fixed to the electrode by drop coating,thus a flexible electrode electrochemical sensor was constructed for the determination of glucose in sweat.The PGE was characterized by infrared spectrometer and scanning electron microscope.Infrared spectroscopy proved two of the most important steps in PET surface modification,carboxylation and amination.After optimizing the working voltage,Prussian blue amount and enzyme amount,a flexible PGE-glucose sensor with good performance was prepared.The proposed glucose sensor revealed a sensitivity of 692.67 nA/mM(22.05μA·mM-1·cm-2)in a linear range from 0.02 to 1.11 mM with a low detection limit of 2.7 μM(S/N=3),and had good repeatability and long-term stability.Then we investigated the effects of pH and temperature on glucose sensor.The PGE-glucose sensor had a good selectivity and was not interfered by lactate,urea,acetaminophen,uric acid,dopamine and ascorbic acid in sweat.The glucose sensor was used to detect human sweat,and the results were consistent with the spectrophotometry,indicating that the flexible electrode electrochemical sensor can be used for the accurate analysis of glucose in sweat.In chapter 3,flexible PGE was also prepared by electroless plating,and then lactate oxidase was fixed to the electrode by drop coating,thus a flexible electrode electrochemical sensor was constructed for the determination of lactate in sweat.After the optimization of Prussian blue amount,enzyme amount and detection time,a flexible PGE-lactate sensor with good performance was prepared.The proposed lactate sensor revealed a sensitivity of 0.6386 μA/mM(20.33 μA·mM-1·cm-2)in a linear range from 0.05 to 9.3 mM with a low detection limit of 0.013 mM(S/N=3),and had good repeatability and long-term stability.Then we investigated the effects of pH and temperature on lactate sensor.The PGE-lactate sensor had a good selectivity and was not interfered by urea,glucose,acetaminophen,uric acid,dopamine and ascorbic acid in sweat.The lactate sensor was used to detect human sweat,and the results were consistent with the spectrophotometry,indicating that the flexible electrode electrochemical sensor can be used for the accurate analysis of lactate in sweat.