Circuit Design
The UV sensor connects to the ESP32-S3 via an analog input, powered by a 3.7 V Li-ion battery with a boost converter. The system is optimized for low power, ensuring extended outdoor use.
Proactive Features
Offline Safety: Functions without internet, preserving privacy and enabling real-time UV alerts for sunscreen use or seeking shade.
UV Sensing: Analog UV sensor (200–375 nm) monitors ambient UV.
RGB LED Alerts: Indicates risk level (Green–Violet from low to extreme).
Reactive Features
Clinical Validation: Used in FDA-approved devices like Nevisense; AURA is the first wearable to miniaturize EIS into a bracelet.
Electrical Impedance Spectroscopy (EIS): Non-invasive technique measuring skin impedance across frequencies, shown in studies to reach ~90% accuracy for skin cancer detection.
Our Implementation
Integration: ESP32-S3 manages AD5933 over I²C, processes results, and transmits via BLE for on-device or app-based AI analysis.
EIS Hardware: Built around the AD5933 impedance converter (1 kHz–100 kHz sweeps).
Custom Analog Front-End: Enables measurement of low skin impedances.
Measurement Protocol: Compare impedance of healthy skin vs. lesion using RMSE to detect abnormalities.
