Wearable Bioimpedance Monitoring: Viewpoint for Application in Chronic Conditions

Abstract

Currently, nearly 6 in 10 US adults are suffering from at least one chronic condition. Wearable technology could help in controlling the health care costs by remote monitoring and early detection of disease worsening. However, in recent years, there have been disappointments in wearable technology with respect to reliability, lack of feedback, or lack of user comfort. One of the promising sensor techniques for wearable monitoring of chronic disease is bioimpedance, which is a noninvasive, versatile sensing method that can be applied in different ways to extract a wide range of health care parameters. Due to the changes in impedance caused by either breathing or blood flow, time-varying signals such as respiration and cardiac output can be obtained with bioimpedance. A second application area is related to body composition and fluid status (eg, pulmonary congestion monitoring in patients with heart failure). Finally, bioimpedance can be used for continuous and real-time imaging (eg, during mechanical ventilation). In this viewpoint, we evaluate the use of wearable bioimpedance monitoring for application in chronic conditions, focusing on the current status, recent improvements, and challenges that still need to be tackled.

Short-Time Impedance Spectroscopy Using a Mode-Switching Nonsinusoidal Oscillator: Applicability to Biological Tissues and Continuous Measurement

“…The real and imaginary parts of . Z X were calculated from the obtained DFT data, and R X , R PX , C PX , and C SX were estimated via the least squares method using Equations ( 7) and ( 8) or ( 9) and (10). In the estimation using Equations ( 9) and (10), first, R X , R PX , and C PX were estimated using Equation ( 9) from the DFT data of the real part of .…”

“…Z X . The estimated R X , R PX , and C PX were then substituted into Equation (10), and C SX was estimated from the DFT data of the imaginary part of . Z X .…”

“…Even when the resistance and capacitance were large, such as R X = 0.91 kΩ and C PX = 9.85 nF, impedance spectra agreed well with the theoretical values (Figure 6). 9) and (10).…”

“…Z X1 for the parallel RC circuits with C PX =1.016 nF and C SX =9.76 nF. The dashed lines represent the fitting curves obtained from Equations ( 9) and (10).…”

“…Bioelectrical impedance analysis has become an important technique in the medical and healthcare fields [1][2][3][4][5][6][7][8][9]. Because the impedance of a living body (bioimpedance) depends on body composition, such as the water content of the body, it reflects medical conditions [10][11][12][13]. Thus, the absolute value and phase of bioimpedance are used to diagnose diseases, and this process is known as bioelectric impedance vector analysis [14][15][16][17][18][19].…”