LU Wei-hu1, LIN Yu1, DU Wen-ya1, HUANG Hong-bin1,2
(1. Department of Electronic Engineering, Jinan University, Guangzhou 510632, China; 2. Key Laboratory of Optoelectronic Information and Sensing Technologies of Guangdong Higher Educational Institutes, Jinan University, Guangzhou 510632, China)
Abstract： Electronic stethoscope is an instrument used for auxiliary determination of patients’ physical condition by collecting and processing heart sounds and lung sounds. Since traditional electronic stethoscopes have low sensitivity and poor low-frequency response, a novel electronic stethoscope is provided in this paper using curved PVDF clamping structure with non-uniform curvature based on the structure of PVDF and silicone rubber substrate. Theoretical analysis and comparison by means of the corresponding inhomogeneous string vibration model show that sensitivity significantly increases for non-uniform curvature than the uniform one. Furthermore, a new electronic stethoscope pickup is developed based on the optimal parameters at the point of maximum sensitivity of non-uniform curvature. Experiment results show that the sensitivity of the pickup can reach 1.7 mV/Pa, which increases by 13.3% compared to the one with the structure of uniform curvature PVDF and silicone rubber substrate that has been studied in recent years. Moreover, flat frequency response characteristics can be retained within the frequency band range of 2-2 kHz , which covers the frequency response range of cardiopulmonary sound collection, thus provides a strong guarantee for complete acquisition of heart and lung sound signals.
Key words： electronic stethoscope； PVDF； non-uniform curvature
CLD number： TN64 Document code： A
Article ID： 1674-8042（2016）01-0084-07 doi： 10.3969/j.issn.1674-8042.2016.01.016
References
［1］ WANG Ji, SHEN Yu-li, LIN Qing. Design of collection system of physiological parameters based on wireless sensor networks. Journal of Electronic Measurement & Instrument, 2009, 23(2)： 94-99.
［2］ ZHANG Xiao-gui, HE Wei, ZHOU Jing, et al. Study on heart sound analyzing instrument based on embedded system. Chinese Journal of Scientific Instrument, 2007, 28(2)： 303-307.
［3］ GUO Xin-ming, GUO Wei-zhen, ZHOU Cheng-wen, et al. Study on noninvasive cardiac reserve monitoring system. Chinese Journal of Scientific Instrument, 2008, 29(4)： 690-695.
［4］ HOU En-xing, ZHAO Zhan, FANG Zhen, et, al. Electronic Stethoscope Based on ZigBee Wireless Transmission Technology. Microcontroller & Embedded Systems, 2011, 11(7)： 49-52.
［5］ Toda M, Tosima S. Theory of curved, clamped, piezoelectric film, air-borne transducers. IEEE Transactions on Ultrasonics Ferroelectrics & Frequency Control, 2000, 47(6)： 1421-1431.
［6］ Toda M, Thompson M L. Contact-type vibration sensors using curved clamped PVDF film. IEEE Sensors Journal, 2006, 6(5)： 1170-1177.
［7］ Lee W K, Chung G S, Baek H J, et al. Heart sounds measurement using PVDF film sensor and their comparison with RR intervals of ECG signals. In： Proceedings of 2012 IEEE-EMBS International Conference on Biomedical and Health Informatics(BHI), Hongkong,Shenzhen, 2012： 864-866.
［8］ Rajala S, Lekkala J. Film-type sensor materials PVDF and EMFi in measurement of cardiorespiratory signals-A review. IEEE Sensors Journal, 2012, 12(3)： 439 - 446.
［9］ XU Jian, Dapino M, Gallego D, et al. Microphone based on polyvinylidene fluoride (PVDF) micro-pillars and patterned electrodes. Sensors & Actuators A Physical, 2009, 153(1)： 24-32.
［10］ Alphonse B, Spiewak A, Walder E, et al. Development of a pressure-sensing handle for a stethoscope. In： Proceedings of IEEE 39th Annual Northeast Bioengineering Conference (NEBEC), 2013： 273-274.
［11］ CHEN Kuan-wei, TSENG Kuo-hua, SUN Che-yuan, et al. Real-time portable physiological signal detection powered by thin acoustic sensors. In： Proceedings of 2012 IEEE 7th International Microsystems, Packaging, Assembly and Circuits Technology Conference (IMPACT), 2012： 347-350.
［12］ SHI Lu, ZHANG Yue, DONG Wei-jie. Research on the relationship between the curvature and the sensitivity of curved PVDF sensor.In： Proceedings of International Symposium on Precision Engineering Measurement and Instrumentation. International Society for Optics and Photonics, 2015： 94461Y-94461Y-6.
［13］ XU Li, ZHANG Kai-jun. Three methods of solving forced oscillation equation with fixation boundary. Journal of Shanghai University of Electric Power, 2008, 24(2)： 195-198.
［14］ XIN Yi, YANG Qing-yu, ZHENG Hao-tian, et al. Study of tactile & slip sensor on structure and signal conditioning circuit design based on PVDF piezoelectric film. Piezoelectrics & Acoustooptics, 2014, 36(1)： 76-78.
基于PVDF非均匀曲率半径结构的高灵敏度电子听诊器
卢威虎1， 林 宇1， 杜文亚1， 黄红斌1,2
（1. 暨南大学 电子工程系， 广东 广州 510632； 2. 暨南大学 广东省高等学校光电信息与传感技术重点实验室， 广东 广州 510632）
摘 要： 电子听诊器是利用电子技术收集处理心肺音， 并依此辅助判断病人身体状况的一种仪器。 针对传统电子听诊器灵敏度低、 低频响应差等缺点， 基于PVDF非均匀曲率半径的弯曲夹紧结构， 提出了一种高灵敏度的电子听诊器设计方案。 通过建立相应的非齐次弦振动模型， 理论分析比较证明了非均匀曲率相比均匀曲率的灵敏度有显著提高， 并优选非均匀曲率半径结构灵敏度最大的参数研制出一款新型电子听诊器拾音器。 实验测试结果表明， 该拾音器的灵敏度达到1.7 mV/Pa， 相较近年来研究的均匀曲率半径PVDF与硅胶衬底组合结构的拾音器灵敏度提高了13.3%。 该拾音器能在2-2 kHz频带范围中保持平坦的频响特性， 涵盖心肺音采集的频响范围， 为较完整地获取心肺音信号提供有力保障。
关键词： 电子听诊器； PVDF； 非均匀曲率半径
引用格式： LU Wei-hu, LIN Yu, DU Wen-ya, et al. Highly sensitive electronic stethoscope based on non-uniform PVDF curvature structure. Journal of Measurement Science and Instrumentation, 2016, 7(1)： 84-90. ［doi： 10.3969／j.issn.1674-8042.2016.01.016］
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