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Development of a Respiratory Inductive Plethysmography Module Supporting Multiple Sensors for Wearable Systems
Department of Biomedical Engineering, Chinese PLA (People’s Liberation Army) General Hospital, 28 Fuxing Road, Haidian District, Beijing 100853, China
The Quartermaster Research Institute of the General Logistic Department, 69 Lumicang Hutong, Dongcheng District, Beijing 100010, China
* Author to whom correspondence should be addressed.
Received: 10 July 2012; in revised form: 10 August 2012 / Accepted: 16 August 2012 / Published: 27 September 2012
Abstract: In this paper, we present an RIP module with the features of supporting multiple inductive sensors, no variable frequency LC oscillator, low power consumption, and automatic gain adjustment for each channel. Based on the method of inductance measurement without using a variable frequency LC oscillator, we further integrate pulse amplitude modulation and time division multiplexing scheme into a module to support multiple RIP sensors. All inductive sensors are excited by a high-frequency electric current periodically and momentarily, and the inductance of each sensor is measured during the time when the electric current is fed to it. To improve the amplitude response of the RIP sensors, we optimize the sensing unit with a matching capacitor parallel with each RIP sensor forming a frequency selection filter. Performance tests on the linearity of the output with cross-sectional area and the accuracy of respiratory volume estimation demonstrate good linearity and accurate lung volume estimation. Power consumption of this new RIP module with two sensors is very low. The performance of respiration measurement during movement is also evaluated. This RIP module is especially desirable for wearable systems with multiple RIP sensors for long-term respiration monitoring.
Keywords: respiratory inductive plethysmography; pulse amplitude modulation; time-division multiplexing scheme; LC oscillator; sensing unit; multiple sensors; wearable system
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MDPI and ACS Style
Zhang, Z.; Zheng, J.; Wu, H.; Wang, W.; Wang, B.; Liu, H. Development of a Respiratory Inductive Plethysmography Module Supporting Multiple Sensors for Wearable Systems. Sensors 2012, 12, 13167-13184.
Zhang Z, Zheng J, Wu H, Wang W, Wang B, Liu H. Development of a Respiratory Inductive Plethysmography Module Supporting Multiple Sensors for Wearable Systems. Sensors. 2012; 12(10):13167-13184.
Zhang, Zhengbo; Zheng, Jiewen; Wu, Hao; Wang, Weidong; Wang, Buqing; Liu, Hongyun. 2012. "Development of a Respiratory Inductive Plethysmography Module Supporting Multiple Sensors for Wearable Systems." Sensors 12, no. 10: 13167-13184.