title: The differential Howland current source with high signal to noise ratio for bioimpedance measurement system.
abstract: The stability and signal to noise ratio (SNR) of the current source circuit are the important factors contributing to enhance the accuracy and sensitivity in bioimpedance measurement system. In this paper we propose a new differential Howland topology current source and evaluate its output characters by simulation and actual measurement. The results include (1) the output current and impedance in high frequencies are stabilized after compensation methods. And the stability of output current in the differential current source circuit (DCSC) is 0.2%. (2) The output impedance of two current circuits below the frequency of 200 KHz is above 1 MΩ, and below 1 MHz the output impedance can arrive to 200 KΩ. Then in total the output impedance of the DCSC is higher than that of the Howland current source circuit (HCSC). (3) The SNR of the DCSC are 85.64 dB and 65 dB in the simulation and actual measurement with 10 KHz, which illustrates that the DCSC effectively eliminates the common mode interference. (4) The maximum load in the DCSC is twice as much as that of the HCSC. Lastly a two-dimensional phantom electrical impedance tomography is well reconstructed with the proposed HCSC. Therefore, the measured performance shows that the DCSC can significantly improve the output impedance, the stability, the maximum load, and the SNR of the measurement system.
authors.affiliation: State Key Laboratory of Precision Measurement Technology and Instruments, Tianjin University, Tianjin, People's Republic of China, and Tianjin Key Laboratory of Biomedical Detecting Techniques and Instruments, Tianjin University, Tianjin, People's Republic of China.
authors.forename: Jinzhen
authors.initials: J
authors.lastname: Liu
authors.affiliation: College of Physics and Electronic Engineering, Shanxi University, Shanxi, People's Republic of China.
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Qiao
authors.affiliation: School of Information Engineering, Hebei University of Technology, Tianjin, People's Republic of China.
authors.forename: Mengjun
authors.initials: M
authors.lastname: Wang
authors.affiliation: Institute of Acupuncture and Moxibustion China Academy of Chinese Medical Sciences, Beijing, China.
authors.forename: Weibo
authors.initials: W
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Precision Measurement Technology and Instruments, Tianjin University, Tianjin, People's Republic of China, and Tianjin Key Laboratory of Biomedical Detecting Techniques and Instruments, Tianjin University, Tianjin, People's Republic of China.
authors.forename: Gang
authors.initials: G
authors.lastname: Li
authors.affiliation: State Key Laboratory of Precision Measurement Technology and Instruments, Tianjin University, Tianjin, People's Republic of China, and Tianjin Key Laboratory of Biomedical Detecting Techniques and Instruments, Tianjin University, Tianjin, People's Republic of China.
authors.forename: Ling
authors.initials: L
authors.lastname: Lin
mesh_terms: D058266:Dielectric Spectroscopy / Q000295:instrumentation / Q000379:methods; D017097:Electric Impedance; D010992:Plethysmography, Impedance / Q000295:instrumentation / Q000379:methods; D059629:Signal-To-Noise Ratio