Self-powered triboelectric sensor for non-invasive heart rate monitoring: An In Vitro pulsatile flow validation

Continuous heart rate (HR) monitoring is important for the early detection and management of cardiovascular disease, yet many wearable sensors are limited by power consumption and measurement artifacts, particularly in optically based technologies. This study presents a low-cost, self-powered triboelectric nanogenerator (TENG) force sensor manufactured using simple laboratory processes and evaluates its potential for HR monitoring. The sensor was characterized under controlled vertical impact testing, demonstrating a linear force-voltage relationship (Pearson correlation coefficient, r = 0.745; p-value, p < 0.001) with a sensitivity of 4.55 V/N. Through parametric optimization of sensor size and surface treatment cycles, a 2 × 2 cm sensor with 8 treatment cycles was selected for cardiovascular testing. Under pulsatile flow conditions generated by a cardiovascular simulation rig, the TENG sensor reliably captured cardiac-like waveforms across a wide physiological HR range (61–182 bpm). HR estimates showed excellent correlation with reference values (r = 0.998), with a mean bias of 0.8 beats per minute (bpm) and 95% limits of agreement of -4.3 to 5.8 bpm, closely matching Millar catheter-based pressure measurements. These results demonstrate the capability of TENG-based sensing to resolve HR-related dynamics under controlled, physiologically relevant conditions and highlight its potential as a high-fidelity, self-powered sensing approach for future low-cost wearable systems, while underscoring the need for further sensitivity enhancement and human validation.