Application of Wearable Nanobiosensor in Heart Rate Monitoring of Exercise Training

During exercise heart rate monitoring, photoelectric sensors are susceptible to motion artifacts, leading to measurement errors. In this paper, a wrist‑worn nanobiosensor is developed. The sensing unit employs a 50 nm thick nanoporous gold film deposited on a flexible PET substrate, functionalized via self‑assembly of 11‑mercaptoundecanoic acid and cardiac troponin I aptamer. A 525 nm LED illuminates the skin, and a photodiode receives the reflected light modulated by blood volume. After passing through a transimpedance amplifier, a DC servo loop, and a 0.5–5 Hz bandpass filter in the analog front end, the signal is sampled at 100 Hz by a 12‑bit ADC and sent to the microcontroller. Digital processing sequentially applies a moving median filter and an adaptive notch filter based on accelerometer‑derived stride frequency estimation to suppress motion artifacts, followed by peak detection and median filtering to output the instantaneous heart rate. Twelve healthy male subjects (aged 27–30 years) exercised on a treadmill at 8 km/h for 20 minutes, with a three‑lead ECG as the gold standard. Experimental results show that the nanobiosensor achieves a mean absolute error of 1.24±0.87 bpm, a root mean square error of 1.52 bpm, and a Pearson correlation coefficient of 0.97 with the ECG. After optimizing the individualized training plan based on the sensor monitoring data, the subjects' physical fitness scores improved from 78.4±5.2 to 88.7±4.6 (paired t‑test, p<0.001). This nanobiosensor provides a high‑precision wearable solution for real‑time heart rate monitoring in exercise training.