Arraying of Two Modified Sensors By Controlled Growth of Co-Cu and Functionalized Carbon Nanotube for Highly Sensitive and Selective Non-Enzymatic Sensing of Glucose in Sweat

Abstract

Due to a relation between glucose in sweat and blood, there is an opportunity to monitor the glucose level of patients non-invasively through sweat. There is a high demand for developing highly selective and sensitive biosensors in order to sense biomarkers like glucose and therefore the diseases based on those biomarkers. However enzymatic sensors are selective to specific biomarkers, they are suffering from high sensitivity to the fluctuation of temperature, oxygen, pH, humidity, detergents, organic reagents and toxic chemicals which subsequently affect their stability, sensitivity, and reproducibility. Therefore, developing non-enzymatic sensors have gotten more attention recently due to their stability against those parameters. But these non-enzymatic sensors are almost non-selective toward just one contaminant. Here we proposed a combination of two sensors that can help us to improve the selectivity of these non-enzymatic sensors. Two electrochemical arrayed sensor has been developed. The first electrochemical sensor has been achieved by controlled growth of cobalt nanowire and copper nanoparticles on carbon substrate in order to measure the glucose level at low concentrations and the second electrochemical sensor has been modified by MWCNT- CO-NH-cyanuric-NH2 in order to measure the uric acid and eliminate the interference of it in glucose measurement results. In order to show the morphology of the glucose sensor, the SEM and EDX have been conducted. Also, the FT-IR test has been shown to confirm the functionalization of MWCNT. The electrocatalytic and electrochemical performance of each sensor has been evaluated in the presence of the various contaminants of sweat. The glucose sensor showed the limit of detection (LOD) of 25 μM of glucose and less than 15% interference by ascorbic acid, sodium bicarbonate, lactic acid at the max range of contaminants in the sweat. For eliminating the interference of uric acid, the second sensor has developed which has no response to the glucose and high sensitivity to the uric acid. The calibration curve of each sensor has been provided and a simple method of arraying has been applied to improve the selectivity of the sensors. At the end, the sweat of a male and a female have been collected continuously over 8hours to compare the glucose level of sweat monitored by the sensors and the blood monitored with the commercial glucometer in the same period of time.