A Portable Sensor for Skin Bioimpedance Measurements

摘要

The costs of pressure injury treatments continue to rise with a steadily aging population and consistent pressure injury incidence rates. Evidence suggests that the bioimpedance of living tissues changes in response to continuous pressure loading and may be useful as an indicator for the onset of pressure injuries. Therefore, the development of a low-cost, accurate, and portable sensor capable of measuring the bioimpedance of human skin has practical significance in the development of pressure injury prevention devices. This paper reports the design and characterization of a system for measuring skin impedance based on the AD5933 impedance analyzer. The sensor was tested for accuracy via measurements of a simplified electrical equivalent skin model. Long duration measurement stability was assessed over 24 hours and skin measurement repeatability was performed on the volar forearm. The power consumption was measured both during idle and when transmitting data for each major component. The sensor demonstrated accuracies similar to those reported for other AFE's used in conjunction with the AD5933. Additionally, the sensor shows good stability over long measurement durations as well as good repeatability when measuring the skin bioimpedance on the volar forearm. Power consumption was as expected and future suggestions for lowering the overall circuit power consumption and size are presented.