Impedance and skin temperature readings at ST-36 while eating

Published: 11 April 2018| Version 3 | DOI: 10.17632/8xvsjv8kj2.3
Fletcher Kovich


Notable features are the contrary motion in the ST36 and +6mm impedance readings. Such contrary motion in nearby impedance readings usually indicates that the feature represents a genuine signal which reflects activity in the related organ, rather than artefact of any sort. The blips on all the plots corresponding with the marker lines may all be movement artefact, introduced when the subject pressed the footswitch with his left foot. At around 110s, there is a large movement artefact which was caused by the subject deciding to move to tuck the blanket into his right sock, since his shin was feeling chilly, and in previous experiments, this had introduced significant artefact on all the temperature readings. However, a striking feature of this is that it also includes a spike on the GB meridian, in contrary motion. This “spike” part of the feature is therefore not artefact but is a genuine signal reflecting gallbladder activity. The spike also appears on the ST36 +6mm sensor, but not on the ST36 sensor itself. This is consistent with the placement of the sensors. The feature begins at the GB meridian, influences the sensor 6mm medial to it, and also the ST36+6mm sensor, which was 30mm medial to it, but here the spike is of less magnitude; and does not appear at all on the ST36 sensor, which was a further 6mm medial. This pattern of the impedance at an acupoint, also influencing the surrounding area has been seen on several other experiments in this project. Note that in Chinese Medicine, it is recognised that the gallbladder enables a person to make decisions. This connection is often seen in clinic today, where a person who has recently been making lots of decisions will often have notable tenderness on the key gallbladder acupoints. Indeed, the subject often feels soreness on the gallbladder meridian on his lower leg, which coincides with periods of heavy thinking and decision making. The other notable feature in the plots is that there is a considerable amount of “contrary-motion” features on the GB plots, indicating that these genuinely reflect gallbladder activity, rather than being artefact of any kind. Also, the impedance of the ST36 and the GB meridian show a general rising trend, which in other experiments in this project is associated with increased activity of the related organs. In this case, food was being digested, so this was expected. The skin temperature readings clearly show the drop in temperature at ST36 and at the GB meridian, relative to the surrounding skin. The skin temperature of any meridian or acupoint is often notably cold to the touch when the associated organ is stressed.


Steps to reproduce

The experiment recorded skin temperature and impedance readings on and near to the acupoint right ST-36 for 600 seconds (10 minutes) continuously while the subject ate a slice of bread. Samples were taken every ms. The subject was a male, aged 57. His Chinese Medicine diagnosis included poor stomach and pancreas function (“Stomach chi deficiency” and “Spleen chi deficiency”) and he was a heavy thinker. The readings were taken on 2 March 2018, starting at 10:54am, and he had not eaten for about 2.5 hours previously. After the sensors were placed, a blanket was used to covered his right leg, so as to avoid the skin becoming chilled and producing artefact due to shivering. The room temperature was 20.4C. The acupoint was located electrically. The first 10 sensors recorded temperature. They were placed in a row, each being 6mm apart, with the 3rd sensor located at the right ST-36 acupoint, and thus the 9th sensor was over the nearby gallbladder meridian. The impedance electrodes were placed over ST-36, 6mm lateral to this; and the second pair were placed level with the 9th and 10th temperature sensors. Sensor 15 was redundant, and sensor 16 was used as a marker. A footswitch was connected to this, which produced a 1.6v output, registering a peak on this channel. The footswitch was operated by the subject, using his left foot, and activated each time he swallowed. Detailed descriptions of the equipment and techniques can be found in the following documents. The signal for the impedance readings was a 200mv sine wave at 40KHz, and a single PicoLog1216 was used to log the data, using the standard Pico software. The readings were then passed through a low-pass filter in MatLab and the results plotted. The experiment was flawed, in that when the subject pressed the footswitch, this introduced movement artefact. The experiment was redesigned to avoid this. However, some useful readings were taken, which is why the results have been published here.


Acupuncture, Traditional Chinese Medicine, Impedance