Skin Hydration Monitoring Using GSR Sensor

Skin hydration is one of the important factors deciding the natural elasticity, anti-aging and protective barrier of the skin. insufficient hydration can result in skin dryness, irritation, premature aging, and the skin becoming more vulnerable to environmental factors which may eventually lead to skin cancer. The continuous assessment of skin hydration is still challenging due to the limited portability and high cost of conventional measurement techniques. This study presents a wearable and non-invasive skin hydration monitoring system designed for real-time hydration assessment and early detection of dry skin conditions.
The proposed system uses a Galvanic Skin Response (GSR) sensor, flex sensor, AD620 instrumentation amplifier, ESP32 microcontroller, buzzer alert module, and wireless web-based monitoring interface. The GSR sensor sense the variations in skin conductance due to different skin moisture content in the stratum corneum, while the flex sensor provides supplementary skin mechanical information. An instrumental amplifier is used to improve signal quality in the signal conditioning stage. The acquired signals are amplified and conditioned using an AD620 instrumentation amplifier before digitized by the 12-bit analog-to-digital converter (ADC) of the ESP32, which produces output values ranging from 0 to 4095. ADC values below 800 indicated dry skin and low hydration, values between the range of 800 and 2000 represented normal hydration, and values above 2000 indicated highly hydrated skin. The experiment is demonstrated on ten people in different timing to validate the accuracy of the system. Under the observation of dermatologist, we have concluded the values and determination were accurate. Among the ten, 5 was detected dry skin who were actually dehydrated. 2 were detected highly hydrated and remaining 3 were normal skin hydration.