Impedance at ST36, ST19, ST21 and Ren12 while drinking chilled water

Published: 10 April 2018| Version 1 | DOI: 10.17632/wrx6pgpm3t.1
Fletcher Kovich


The experiment was intended to measure any change in impedance on key stomach-related acupoints that occur when the subject drank chilled water on an empty stomach. To monitor the impedance, it was decided to use an intermittent signal, to rule out the possibility that a continuous signal applied on key acupoints affects the stomach function and so provides misleading results. THE RESULTS Most of the acupoints on the body are repeated in pairs, on the left and right. It is usually stated that both instances of these acupoints have the same effect. However, the left and right ST36 plots, show different activity. This pattern is often seen in this project’s experiments, which suggests that the left and right acupoint reflect different aspects of an organ’s function. The impedance at both the left and right ST36 acupoints moves in contrary motion, suggesting that this pattern is a genuine reflection of the related organ’s function, rather than being artefact, which would produce similar motion in the impedance changes on two locations only 6mm apart. Impedance of the right ST21 acupoint shows a sharp drop immediately after the start and end of the subject drinking the chilled water. Since samples were only taken once every 4s, there is not enough detail to show any response accurately. Nonetheless, there seems to be a clear response in this acupoint’s impedance. And again, the trend of the two traces moves in contrary motion, suggesting that the features are a genuine reflection of the related organ’s function, rather than being artefact. The Ren12 plots move in contrary motion, but apart from this, there is not enough detail to be able to confidently identify any response in relation to the markers, except for a contrary motion feature at 160s, some 15s after the second marker. The left ST19 acupoint registered a distinct drop in impedance after the first swallow, which is less evident in the +6mm location. But again, the 4s sample rate does not provide enough detail to make confident observations about the degree of the response, nor its delay after the first swallow. The right ST19 acupoint displayed a different response to the left; the right’s response was a gradual increase in the gradient between the acupoint and the +6mm location. Again, this follows the pattern of the left and right acupoint perhaps reflecting a different aspect of the related organ. The results were comparable to those obtained when using a continuous signal, which suggests that using a continuous signal does not stimulate the acupoints unduly and hence provide misleading results, though this possibility should always be born in mind. This experiment has been redesigned to use a continuous signal, sampled at the rate of 1000 samples per second, so that the responses can be captured in more detail. The subject also reported an ache centred on Ren12, which was induced by drinking the chilled water, and this will also be monitored in the follow-up experiment.


Steps to reproduce

The experiment monitored the impedance at key stomach-related acupoints while the subject drank chilled water on an empty stomach. The acupoints were first located by an experienced TCM acupuncturist, then the point of lowest impedance was located electrically. The electrodes were cone shaped with a tip of around 1mm diameter, and each electrode assembly contained two electrodes, 6mm apart. Gel was used to make the contact with the skin, and a standard ECG electrode was used to make an earth connection. The signal used was a 200mv sine wave at 10khz, which was passed into the electrodes and the resultant voltages monitored. The signal lasted for only 28ms, was switched off for 4s, then the cycle repeated. For each sample, a reading was made every ms, which produced 28 readings, and these were averaged to produce each single sample. This approach was used to rule out the possibility that a continuous signal may stimulate the acupoints and thus affect the organ being monitored. The data logger, and also the control of the signal, was controlled via a VBA macro in an Access database. Full details of all the techniques and equipment used can be found in the following documents. The subject was a male, aged 34. In TCM terms, he had poor stomach and pancreas function (“Stomach chi deficiency” and “Spleen chi deficiency”). The experiment was conducted on 27 March 2018, and began at 9:16am. The subject had not eaten or drunk anything since waking. The room temperature was 22.4C, and the drinking water was chilled to 1.5C. The subject sat in a chair during the experiment.


Acupuncture, Impedance