Wearable Sensing of In-Ear Pressure for Heart Rate Monitoring with a Piezoelectric Sensor

Sensors

Jang-Ho Park⁴  Dae-Geun Jang²  Jung Wook Park¹  Se-Kyoung Youm³ 

[1] Creative Innovation Center, LG Electronics Co. Ltd., Seoul 137-893, Korea; E-Mail:;Samsung Advanced Institute of Technology, Samsung Electronics Co. Ltd., Suwon 443-803, Korea;Industry-Academic Cooperation Foundation, Dongguk University, Seoul 100-715, Korea; E-Mail:;Medical IT Convergence Research Center, Korea Electronics Technology Institute, Seongnam 463-816, Korea; E-Mail:

关键词: wearable heart rate monitoring;    in-ear pressure variance;    piezoelectric sensor;   

DOI  :  10.3390/s150923402

来源: mdpi

【 摘 要 】

In this study, we developed a novel heart rate (HR) monitoring approach in which we measure the pressure variance of the surface of the ear canal. A scissor-shaped apparatus equipped with a piezoelectric film sensor and a hardware circuit module was designed for high wearability and to obtain stable measurement. In the proposed device, the film sensor converts in-ear pulse waves (EPW) into electrical current, and the circuit module enhances the EPW and suppresses noise. A real-time algorithm embedded in the circuit module performs morphological conversions to make the EPW more distinct and knowledge-based rules are used to detect EPW peaks. In a clinical experiment conducted using a reference electrocardiogram (ECG) device, EPW and ECG were concurrently recorded from 58 healthy subjects. The EPW intervals between successive peaks and their corresponding ECG intervals were then compared to each other. Promising results were obtained from the samples, specifically, a sensitivity of 97.25%, positive predictive value of 97.17%, and mean absolute difference of 0.62. Thus, highly accurate HR was obtained from in-ear pressure variance. Consequently, we believe that our proposed approach could be used to monitor vital signs and also utilized in diverse applications in the near future.

【 授权许可】

CC BY   
© 2015 by the authors; licensee MDPI, Basel, Switzerland.