An improved device for bioimpedance deviation measurements based on 4-electrode half bridge.
Researches on monitoring the body fluid changes have attracted much attention during recent years. Real-time bioimpedance deviation detection has good potential for evaluating body fluid changes. In this paper, an improved device based on the self-balancing half bridge and the 4-electrode technique is proposed, which is able to detect minor bioimpedance deviations. The 4-electrode technique is used to remove the interference from contact impedance. Furthermore, the automatic balancing half bridge is utilized to deduct the high-level static impedance baseline, and thus, the dynamic range is enlarged. Moreover, a digital lock-in algorithm based on oversampling improved the effective resolution of the system. Validation experiments show that the minimum bioimpedance deviation measured in the experiment can reach 1 Ω even when the bioimpedance baseline is 10 kΩ and the noise level is low. The system has advantages of high resolution, high magnification, large dynamic range, and good self-adaptability for bioimpedance deviation detection.
School of Precision Instrument and Opto-Electronics Engineering, Tianjin University, 300072 Tianjin, China.
Yang
Y
Liu
College of Physics and Electronics Engineering, Shanxi University, 030006 Taiyuan, China.
Xiaoyan
X
Qiao
School of Precision Instrument and Opto-Electronics Engineering, Tianjin University, 300072 Tianjin, China.
Gang
G
Li
School of Precision Instrument and Opto-Electronics Engineering, Tianjin University, 300072 Tianjin, China.
Ling
L
Lin
D000818:Animals; D001826:Body Fluids; D017097:Electric Impedance; D004566:Electrodes; D006801:Humans