GlassTENG: Self-Powered Triboelectric Nanogenerator based Sensing of Pulse, Jaw, and Upper Facial Activity from Everyday Glasses

Smart glasses are an ideal platform for physiological monitoring because they are worn daily and maintain consistent contact with the face. However, existing sensors like optical photoplethysmography (PPG) or electromyography (EMG) are power-hungry, requiring bulky batteries that limit long-term wearability. The authors introduce GlassTENG, a self-powered sensing platform that integrates custom-fabricated triboelectric nanogenerators (TENGs) into a standard glasses frame to monitor physiological signals without the need for high-power electronics.

The researchers embedded three TENG sensors into a glasses frame at anatomically strategic locations: the nasal bridge (angular artery), the anterior temple (superficial temporal artery), and the posterior temple (temporalis muscle). These sensors convert mechanical energy from arterial pulses and muscle movements directly into electrical signals. To process these signals, the team developed a high-impedance analog front-end that consumes only 1.36 microwatts per channel, significantly lower than traditional wearable sensors. The system was validated in a 20-participant study, where it was tested for its ability to classify six facial activities and estimate heart rate against a ground-truth chest-strap monitor.

GlassTENG demonstrated high performance in both cardiovascular and activity monitoring. The system achieved a mean absolute error of 1.82 beats per minute (BPM) for heart rate estimation, showing strong agreement with clinical-grade chest straps. For activity recognition, a Random Forest classifier achieved 93.8% accuracy across six distinct jaw and upper facial activities, such as blinking, clenching, and tapping. Participant feedback indicated that the design is comfortable and holds potential for daily use, particularly for wellness and fitness tracking.