Abstract
A low-power stable wideband current source for acupuncture point skin impedance measurements has been designed employing a differential architecture and negative feedback. The circuits extend bandwidth to 1 MHz, reducing harmonic distortion to 0.24% at 1 MHz. The output impedance is 37 MΩ at 100 kHz and 11 MΩ at 1 MHz. The stability of the output current of the current source when connected to different loads is below 0.1% at frequencies up to 500 kHz and increases to 0.74% at 1 MHz. The circuit was manufactured in a 0.13-μm CMOS technology and measured results are presented. The area of the current source is 0.09 mm2 and its consumption is 1.2 mW. It is intended for low-power acupuncture point skin impedance measurements.
Highlights
Skin impedance measurement has been used for more than 50 years to measure changes in skin impedance at acupuncture points to help diagnose diseases and monitor the effectiveness of treatment [1, 2]
Install the current source on impedance measuring device to obtain the impedance characteristics of human meridian acupoints and nonacupoint tissue specimens. is test uses a current source chip to test the electrical impedance of the skin around the human acupuncture point PC4 Ximen and nonacupuncture point PC4 Ximen surrounding area. e test data were used to distinguish the difference in electrical impedance between the skin around PC4 and nonacupoint PC4 area
One end of the electrodes is connected to the chip output port for receiving current from the current source chip and the other end is in contact with the measured acupuncture point
Summary
Skin impedance measurement has been used for more than 50 years to measure changes in skin impedance at acupuncture points to help diagnose diseases and monitor the effectiveness of treatment [1, 2]. Journal of Healthcare Engineering current ensures low distortion and meets low-power requirements for acupuncture point skin impedance measurements which is limited in existing integrated current source [18–22]. Current source design [24] uses a Howland topology to achieve a high output impedance (1.7 MΩ at 50 kHz) for the current source by using a resistor with a precision tolerance of 0.01%. E integrated current source proposed in [26] uses an active inductive load structure to implement an open-loop operational transduction amplifier (OTA), and its current source can reach an output impedance of 500 kΩ at 500 kHz, but the supply voltage is too high and the bandwidth is less than 1 MHz. In this paper, we propose a low-power stable wideband current source for acupuncture point skin impedance measurements.
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