Kim Minjae, Teeravichayangoon Premravee, Park Daehyeok, Shao Jiaying, Seong Geunchang, Seok Dongyeol, Kim Chul
Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea.
Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea; Program of Brain and Cognitive Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea.
Biosens Bioelectron. 2025 Dec 1;289:117838. doi: 10.1016/j.bios.2025.117838. Epub 2025 Aug 6.
Continuous monitoring of heart activity, particularly electrocardiogram (ECG) waveforms and heart rate variability (HRV), is essential for the early detection of cardiac diseases. However, conventional wearable ECG systems typically require direct skin contact and external software for signal acquisition and analysis, limiting user comfort and long-term usability. This study presents an unobtrusive contactless bed-embedded system that enables wearable-free, comfortable, and precise monitoring of ECG and HRV without the need for the subject to undress. Flexible active electrodes achieve high signal acquisition performance and strong noise immunity by employing double active shielding for noise reduction of 64 dB. The analog front-end has an input-referred noise of 0.49 μV within the QRS bandwidth. Further noise reduction of 27.5 dB is obtained by a non-contact driven-right-leg. Real-time signal denoising, R-peak detection, and HRV calculation are performed on the field-programmable gate array for on-hardware processing, running a stationary wavelet transform and adaptive thresholding. The system demonstrates over 70% R-peak detection precision for users wearing even thick clothing during a 5-minute measurement. This system enables R-peak detection when the subject makes slight movements.
持续监测心脏活动，尤其是心电图（ECG）波形和心率变异性（HRV），对于心脏病的早期检测至关重要。然而，传统的可穿戴式ECG系统通常需要直接接触皮肤并借助外部软件进行信号采集和分析，这限制了用户的舒适度和长期可用性。本研究提出了一种不引人注意的非接触式床嵌入式系统，该系统无需受试者脱衣即可实现无穿戴、舒适且精确地监测ECG和HRV。柔性有源电极通过采用双重有源屏蔽来降低64 dB的噪声，从而实现了高信号采集性能和强抗噪声能力。模拟前端在QRS带宽内的输入参考噪声为0.49 μV。通过非接触式驱动右腿电路可进一步降低27.5 dB的噪声。实时信号去噪、R波检测和HRV计算在现场可编程门阵列上进行硬件处理，运行平稳小波变换和自适应阈值处理。该系统在5分钟测量期间，对于穿着厚衣服的用户，R波检测精度超过70%。当受试者轻微移动时，该系统也能够进行R波检测。
