Electrical Characterisation of PEDOT: PSS/GO in Exposed to Different pH and the Potential Application as Sensor

Health monitoring devices are required to detect or monitor diseases that have emerged in our increasingly modern world. As a result, more frequent health monitoring is needed. However, hospital visits are time-consuming, and some checkup procedures of sample retrieval, such as blood, urine, and many others, are sometimes painful. Since the development of nanotechnology, wearable biosensors have reduced the need for hospital visits by continuously monitoring physiological and health status. Therefore, there is a current need for research into reliable real-time health monitoring using the most suitable flexible nonmetal material to replace metal material and avoid these problems. In this work, a flexible pH sweat sensor is developed on a polydimethylsiloxane (PDMS) based flexible substrate. PEDOT: PSS/GO, which is deposited onto a 2 cm x 1 cm area by using a drop casting technique on a copper strip, is the sensing material used to detect acidity and alkalinity of sweat, whereas PVA/PAA hydrogel is used in the top layer to absorb the sweat sample. The fabricated sensors with a base resistance of 0.7 Ω show good adsorption of the targeted analyte with a sensitivity of 0.5 Ω/ ml in acidic pH (pH4) and 0.71 Ω/ ml in alkaline pH (pH 10) detection. In addition, based on reliability tests, the sensor shows a stable base resistance of 0.7 Ω as the sensor is bending at 30°, 60°, and 90°. On the other hand, the hydrogel surface demonstrates good wettability as 2 ml of pH solution is dropped onto the top hydrogel surface. In conclusion, the developed nonmetal-based pH sweat sensors have demonstrated excellent performance with good sensitivity and reliability toward pH detection. Therefore, the materials and configuration could be applied as an alternative to the pH sweat sensor and potentially marketable as a patch sensor.