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Kai Yang

Biography

Enrollment Date: 2012

Graduation Date：2015

Degree：M.S.

Defense Date：2015.06.04

Advisors：Hanjun Jiang

Department：Institute of Microelectronics，Tsinghua University

Title of Dissertation/Thesis：KeyTechnology Study on Wearable Fetal Heart Sound Monitoring System

Abstract:
The fetal heart sounds are the sounds generated by the heartbeats of the fetus, which are a key element to monitor the health status of the fetus. The Doppler ultrasonic monitor is widely used in fetal heart monitoring. Its principle is to transmit the ultrasound to the fetal heart and extract the fetal heart rate with the Doppler effect of the return signal. However, long-term ultrasonic exposure may bring harm to the fetus, and the Doppler fetal heart monitors are mostly bulky and not suitable for portable usage. Therefore, a fetal heart monitoring method which is safe, portable and suitable for long-term wearable monitoring is in need. The passive fetal heart monitoring is a fetal heart monitoring method without active energy transmission, which uses acoustic sensor to passively collect the fetal heart sound signal on the surface of the pregnant woman’s abdomen. In this paper, a wearable hardware system based on passive fetal heart monitoring is developed according to the features of fetal heart sounds, which can effectively collect, analyze and store the feeble fetal heart sound signal. The system is composed of a wearable fetal heart sound sensor, a portable base station and a remote data center. The wearable sensor collects the fetal heart sounds and transmits them to the portable base station. The portable base station is usually a smart phone which provides user interface to control the sensor. It can also transmit the fetal heart sound data to the remote data center after preprocessing. The remote data center can store the heart sound signal for long and analyze it in detail. The wearable sensor features low power consumption, small size and high resolution. Its current consumption is 1.9 mA in long-term monitoring and it can work continually for 48 hours. Its maximum diameter is 41 mm, and its height is 33 mm. The acoustic system exports the fetal heart sound signal with an amplitude of 1~2 mV which can be accurately quantized by a 24-bit ADC. The signal processing methods for the feeble heart sound signal are also a key part in this paper. An effective algorithm for fetal heart sound processing is proposed which is composed of fetal heart sound enhancement, motion artifact removal and fetal heart rate extraction. An experiment on the algorithm with 28 fetal heart sound samples from the proposed wearable system shows that the algorithm can effective enhance the fetalheart sounds and make them audible by human ears. It can also remove the motion artifacts caused by friction and the average fetal heart rate is calculated with 2.2% error.

Publications

Papers：：

[1] Jingjing Dong,Hanjun Jiang,Kai Yang,Zhaoyang Weng,Fule Li,Jianjun Wei,Yanqing Ning,Xinkai Chen,Zhihua Wang, A wireless body sound sensor with a dedicated compact chipset, Circuits Systems and Signal Processing, Vol.36, No.6, pp. 2341 - 2359, 2017.

[2] Heng Liu,Hanjun Jiang,Kai Yang,Zhexiang Chi,Fule Li,Chun Zhang,Zhihua Wang, A Fully Integrated Wireless SoC for In-Body pH and Temperature Continuous Monitoring, ISOCC 2015, 2015.

[3] Kai Yang,Hanjun Jiang,Wendi Yang,Frederic Mes,Chun Zhang,Zhihua Wang,Qingliang Lin,Wen Jia, Lifetime tracing of cardiopulmonary sounds with low-power sound sensor stick connected to wireless mobile network, Analog Integrated Circuits and Signal Processing, Vol.81, No.3, pp. 623 - 634, 2014.

[4] Zhexiang Chi,Hanjun Jiang,Jingpei Xia,Heng Liu,Zhaoyang Weng,Jingjing Dong,Kai Yang,Zhihua Wang, A smart capsule for in-body pH and temperature continuous monitoring, MWSCAS 2014, pp. 314 - 317, 2014.

[5] Wendi Yang,Kai Yang,Hanjun Jiang,Zhihua Wang,Qingliang Lin,Wen Jia, Fetal heart rate monitoring system with mobile internet, ISCAS 2014, pp. 443 - 446, 2014.

[6] Qi Tang,Hanjun Jiang,Wan Wang,Kai Yang,Chun Zhang,Zhihua Wang, Heart rate algorithm based on a Band-Aid-like electrocardiogram, Electronic Design Engineering, Vol.21, No.20, pp. 137 - 140, 2013.

[7] Zhihua Wang,Hanjun Jiang,Kai Yang,Lingwei Zhang,Jianjun Wei,Fule Li,Baoyong Chi,Chun Zhang,Shouhao Wu, Qingliang Lin, Wen Jia, Lifetime Tracing of Cardiopulmonary Sounds with Ultra-Low-Power Sound Sensor Stick Connected to Wireless Mobile Network, NEWCAS 2013, pp. 1 - 4, 2013.

[8] Kai Yang,Zhuan He,Wendi Yang,Qi Tang,Dongmei Li,Zhihua Wang,Qingliang Lin,Wen Jia, Heart Sound Denoising Using Computational Auditory Scene Analysis for a Wearable Stethoscope, MWSCAS 2013, pp. 1220 - 1223, 2013.

[9] Zhihua Wang,Kai Yang,Wan Wang,Hanjun Jiang,Shouhao Wu,Qingliang Lin,Wen Jia, Sound monitoring based wireless healthcare and a typical implmenation for heart rate monitoring, EDSSC 2013, pp. 1 - 2, 2013.

[10] Kai Yang,Hanjun Jiang,Jingjing Dong,Chun Zhang,Zhihua Wang, An adaptive real-time method for fetal heart rate extraction based on phonocardiography, BioCAS 2012, pp. 356 - 359, 2012.