ArticlePDF Available

Impedance analysis of acupuncture points and pathways

Authors:
  • VUJE, a.s. Trnava, Slovakia

Abstract and Figures

Investigation of impedance characteristics of acupuncture points from acoustic to radio frequency range is addressed. Discernment and localization of acupuncture points in initial single subject study was unsuccessfully attempted by impedance map technique. Vector impedance analyses determined possible resonant zones in MHz region.
Content may be subject to copyright.
Impedance analysis of acupuncture points and pathways
This article has been downloaded from IOPscience. Please scroll down to see the full text article.
2011 J. Phys.: Conf. Ser. 329 012034
(http://iopscience.iop.org/1742-6596/329/1/012034)
Download details:
IP Address: 78.98.171.4
The article was downloaded on 04/03/2012 at 08:14
Please note that terms and conditions apply.
View the table of contents for this issue, or go to the journal homepage for more
Home Search Collections Journals About Contact us My IOPscience
Impedance analysis of acupuncture points and pathways
Michal Teplan1, Marek Kukučka2, Alena Ondrejkovičová3
1Institute of Measurement Science, Slovak Academy of Sciences, Dúbravská cesta 9,
84104 Bratislava, Slovakia
2Department of radio electronics, Faculty of Electrical Engineering and Information
TechnologySlovak University of Technology, Ilkovičova 3, 81219 Bratislava,
Slovakia
3Liming, Mýtna 5, 81107 Bratislava, Slovakia
E-mail: michal.teplan@savba.sk
Abstract. Investigation of impedance characteristics of acupuncture points from acoustic to
radio frequency range is addressed. Discernment and localization of acupuncture points in
initial single subject study was unsuccessfully attempted by impedance map technique. Vector
impedance analyses determined possible resonant zones in MHz region.
1. Introduction
In acupuncture and related fields it is assumed that there are special pathways in the body called
meridians which are connected to main body systems, such as cardio-vascular, respiratory, digestive,
etc. In this concept the pathways are exposed to the surface of human body in so called acupuncture
points localized on skin surface. Although use of acupuncture is relatively well established in Western
medicine as a complementary diagnostic and therapeutic tool, its physical and medical
characterization is still largely unknown.
According to Zhang [1] within human body there is an invisible dissipative structure of EM field
which in mainly composed of an interference patterns of standing waves in the resonance cavity of
human body under the condition of permanent support of energy in an open system. This invisible
structure may correspond to some extent to the mysterious acupuncture system and is closely related
to different modalities of energetic medicine.
With noninvasive skin measurements typical values of impedance are around the range 100 k Ω
and capacitive elements around fractions of μF. Some of the previous studies showed that electrical
characteristics like impedance and capacitance at acupuncture points may show distinct values in
comparison to values obtained from surrounding non-acupuncture points. Acupuncture sites were
found to possess lower impedance and higher capacitance. However, some studies found no
distinction from surrounding tissues. According to the review by Ahn et al. [2] preliminary evidence
supports these findings however it is still impossible to determine whether acupuncture structures
possess distinct electrical characteristics until better quality studies are performed.
9th International Fr¨
ohlich’s Symposium IOP Publishing
Journal of Physics: Conference Series 329 (2011) 012034 doi:10.1088/1742-6596/329/1/012034
Published under licence by IOP Publishing Ltd
1
Segments of human body may be modelled by electrical circuits. Complex electronic
circuitry consists of conductors, capacitors and inductances. Resistive component reflects
mainly proportion of liquids comprised in the tissue together with liquid properties of current
conductance depending on concentration of different ions. Capacitive component reveals
integrity of cell membranes. Phase angle is in bioelectrical impedance analysis used as an indicator
for disease, hydration and nutritional status. Better overall health status should correspond with higher
phase angle. Fukumoto [3] suggested a new approach for acupuncture point determination by
constructing a ratio of imaginary and real part of complex impedance.
Within wide frequency range it may be beneficial to focus on the question whether
resonant behavior may occur in systems of interest. Focus is directed to frequency windows
with values of impedance modulus and/or phase angle different from values at surrounding
frequencies. Basic resonance phenomena is often demonstrated on simple serial RLC circuits
where inductance component is vitally needed in order to compensate capacitive part. Resonance
should occur when phase angle vanishes. In biological systems inductance appears to play no
significant role. However, also circuits with only resistive and capacitive components may possess
resonant behaviour. Reichmanis et al. showed in [4] such an example: Infinite transmission line
consisting of elements built from serial resistance with another resistance in parallel with capacitance
(figure 7, model B) and terminated by its characteristic impedance.
Aim of the initial part of our study was to prepare methodology for several types of impedance
measurements in order to study resonant behaviour of acupuncture system. Our investigation was
focused on critical assessment of electrical properties of single acupuncture points and properties of
meridians measured between two acupuncture points of the same meridian. In the first step we
attempted to localize acupuncture points from impedance modulus maps. Then followed investigation
of electrical properties of acupuncture system by vector impedance analysis in acoustic and
radiofrequency range.
2. Methods
All data were measured from single healthy subject (corresponding author, male, 36 years old).
Acupuncture points were chosen according to their accessibility left arm, diversity of acupuncture
pathways and significance regarded to therapeutic use in acupuncture medical system. The following
points were used: Large intestine LI-4 and LI-11, heart HT-3 and HT-7, lungs LU-5and LU-7,
pericardum PC-6 and PC-3, and triple warmer TW-3, TW-8, and TW-9. Experienced clinical
acupuncturist localized all the points and afterwards they were labeled by marker and photographed.
Control points were taken several centimeters apart from acupuncture points, namely in LI-4 and HT-3
area.
For the first part, impedance maps were measured with a grid of 64 brass telescopic needle
electrodes (figure 1). Their telescopic tips maintained balanced pressure across measured area with
side lenght 17.5 mm. Distance between neighbouring tips was 2.5 mm. Monopolar arrangement was
applied with clamp reference electrode on the opposite arm (surface 6 cm2). Frequency of probing
current was 1 kHz. Unique recording system was controlled from Matlab environment via USB port.
Prototype comprised microprocessor (Atmel ATmega16) with serial port and eight A/D converters
with 10-bit resolution. The device measured voltage difference between active and passive electrodes
based on spike detectors. Consequently, off-line transformation from voltage into impedance was
performed based on interpolation of voltage data corresponding to known resistances.
For the second and the third experimental setup adhesive disposable Ag/AgCl ECG electrodes
(Ambu Blue Sensor P) with measuring area 154 mm2 and PUR sponge with highly conductive wet gel
were used (figure 2). Electrode polarization effect was minimized by Ag/AgCl coating [5]. These
active electrodes were placed on acupuncture point of the left arm.
9th International Fr¨
ohlich’s Symposium IOP Publishing
Journal of Physics: Conference Series 329 (2011) 012034 doi:10.1088/1742-6596/329/1/012034
2
Figure 1: Brass needle electrodes with telescopic tips.
Figure 2: Adhesive disposable Ag/AgCl ECG electrodes.
3. Results and discussion
3.1. Impedance maps
We have found only one study depicting impedance/conductance maps of acupuncture point. Becker
et al. [6] found higher conductance in the centre of acupuncture point surrounded by roughly circular
equiconductance pattern (figure 3).
9th International Fr¨
ohlich’s Symposium IOP Publishing
Journal of Physics: Conference Series 329 (2011) 012034 doi:10.1088/1742-6596/329/1/012034
3
Figure 3: Sample of conductance map on acupuncture point LI-4 from study of Becker et al. [6].
Impedance maps from 11 acupuncture points did not consistently support any map structure
with similar characteristics and pattern. In most of the cases distinctive minima surrounded by
circular patterns were not found. In many maps there was no isolated depression in impedance
modulus (figure 4). To show one of the most resembling map, there is local extreme in a form of
minima at the upper left picture of figure 4 with certain indication of surrounding pattern. Control
maps showed similar structures: irregular extremities spread across the measured skin surface,
often with considerable variations within mm distance: Readings from neighbouring electrode
sites differed up to the one order of magnitude. We found that repeatability of the same map was
valid only under very restricted conditions with immediate repetition and without removing the
electrode grid from the skin. As a next step we plan to localize acupuncture points more precisely
into the centre of the map and test different pressure levels of telescopic needles.
9th International Fr¨
ohlich’s Symposium IOP Publishing
Journal of Physics: Conference Series 329 (2011) 012034 doi:10.1088/1742-6596/329/1/012034
4
Figure 4: Sample of impedance maps of acupuncture points LI-4 and TW-3. Lower left: control
point. Lower right: 3D plot.
3.2. Impedance in acoustic frequency range
For impedance measurement in acoustic frequency range Tesla BM 595 RLCG meter was used.
Copper reference electrode in a shape of cylinder was placed under the right thigh. Supported
frequency range was 100 20 000 Hz.
No distinction of acupuncture points from control points was obtained. On the contrary to
expectations (e.g. [7]), control points had not higher impedance modulus (figure 5) in comparison to
acupuncture points. While in impedance modulus all the curves were slightly decreasing, phase angle
curves (figure 6) did not exhibit monotonous behaviour for most of the cases.
9th International Fr¨
ohlich’s Symposium IOP Publishing
Journal of Physics: Conference Series 329 (2011) 012034 doi:10.1088/1742-6596/329/1/012034
5
Figure 5: Impedance modulus dependance on frequency in acoustic frequency range. Black color
holds for control points. Note the only meridian at the bottom of the legend.
Figure 6: Phase angle in acoustic frequency range. Black color holds for control points. Note the
only meridian at the bottom of the legend.
From obtained data it is possible to fit impedance |Z(f)| according to simple circuit models depicted
in figure 7. Johng et al. [7] succesfully fitted their data according to model from scheme A of figure 7.
Resulted estimates of one resistive and two capacitive components represented electrical elements
based on skin layers: epidermis on the surface with dry tissue of stratum corneum (parallel R with C)
together with serial R representing dermis. Their estimates agreed with distinction of acupuncture
points as to be sites with smaller resistance and larger capacitance.
102103104105
1
10
100
frequency [Hz]
impedance [k ]
control1
control1
control2
control3
LI4
LI4
TW3
HT7
LU7
PC3
LI11
LI11
TW8
TW9
LI4-LI11
102103104105
10
40
20
5
frequency [Hz]
phase angle [°]
control1
control1
control2
control3
LI4
LI4
TW3
HT7
LU7
PC3
LI11
LI11
TW8
TW9
LI4-LI11
9th International Fr¨
ohlich’s Symposium IOP Publishing
Journal of Physics: Conference Series 329 (2011) 012034 doi:10.1088/1742-6596/329/1/012034
6
Figure 7: Electrical equivalent circuits from [2]: Model A was proposed by Johng et al. [7], model
B by Rosendal [8].
Preliminary fitting of our data based on models from figure 7 was not appropriate, as the regression
error was too large. In the next step we plan to build more complex model with more circuit elements.
Also, relatively large surface of active electrode (1.5 cm2) could cause that the largest current density
flowed at electrodes periphery and thus could avoid active points.
3.3. Impedance in radio frequency range
Depth of penetration into the skin is determined by AC frequency of measurement. Direct and low-
frequency currents penetrates mainly only into the epidermis dominated by the dead stratum corneum.
Moreover, at low frequencies (typically below several hundred kilohertz), the conductivity of the
tissue is dominated by conduction in the electrolytes in the extracellular space. In order to investigate
properties of deeper tissue structures and intracellular space as well, experimental setup with radio
frequency impedance analyzer was prepared.
At radio frequencies, the tissue exhibits the beta dispersion, centered in the range 0.1 to 10 MHz,
due to the charging of cell membranes through the intracellular and extracellular media. Above the
beta dispersion, the cell membranes have negligible impedance, and the current passes through both
the extracellular and intracellular media. On the other hand ionic flow is diminishing as relatively
heavy ions are not able to adjust to rapid change of current direction.
Tomco TE1000 radio frequency impedance analyzer was applied with ECG active electrodes
placed at acupuncture points and copper cylinder reference electrode hold in the right palm. The
measurements were realized in the electromagnetically shielded room. Frequency from 0.5 150 MHz
range was scanned with 1.5 MHz step.
The variations in impedance values across the whole frequency range were at the level of 1-2
orders of the magnitude (figure 8). Observed lower impedance zones around 50 and 70 MHz could
point to the zone with improved information transmission in the studied tissues. Moreover, both zones
bear another distinct property - zero phase angle (figure 9). These are the characteristics of resonant
behaviour. Resonant properties may be demonstrated by either negative or positive impedance peaks.
Different acupuncture subsystems differ from each other in resonant frequency around 50 MHz up to
10 MHz. A few another null angle zones appeared in the figure 8 while not binding to impedance
extremities.
9th International Fr¨
ohlich’s Symposium IOP Publishing
Journal of Physics: Conference Series 329 (2011) 012034 doi:10.1088/1742-6596/329/1/012034
7
Figure 8: Impedance modulus for acupuncture (colored) and control (black) points. Note the only
meridian at the bottom of the legend.
Figure 9: Phase angle for acupuncture (colored) and control (black) points. Note the only meridian
at the bottom of the legend.
Acupuncture in comparison to control points seems to exhibit higher variations in impedance. Also,
the main impedance minima at 50 MHz is for acupuncture points shifted to higher frequencies. The
same holds for null angle characterizing resonant frequency around 50 MHz. The only acupuncture
pathway measured between two acupuncture points exhibits distinct behaviour: sharper extremities
and higher number of zero phase crossing.
Overall, the preliminary results require more data accumulation and further analysis. Experiences
with measurement techniques confirm the fact that results may be heavily dependent on some of the
50 100 150
102
103
104
frequency [MHz]
impedance [k ]
control1
control2
control3
LI4
TW3
HT7
LU7
PC3
LI11
TW8
TW9
LI4-LI11
50 100 150
-80
-60
-40
-20
0
20
40
frequency [MHz]
phase angle [°]
control1
control2
control3
LI4
TW3
HT7
LU7
PC3
LI11
TW8
TW9
LI4-LI11
9th International Fr¨
ohlich’s Symposium IOP Publishing
Journal of Physics: Conference Series 329 (2011) 012034 doi:10.1088/1742-6596/329/1/012034
8
following measurement characteristics: skin surface, presence of sweat glands, electrode geometry and
polarizability, contact pressure, time fluctuation of electrical properties, etc.
Impedance analysis of acupuncture system deserves further attention along the need for improved
understanding of physical mechanisms behind basic functioning of this relatively broadly used
medical modality.
4. Acknowledgement
This work was supported by Slovak Grant Agency for Science (grant VEGA No 2/0210/10 and
1/0285/09).
References
[1] Zhang CL 2002 Skin resistance vs. body conductivity Frontier Perspectives 15-25
[2] Ahn AC, Colbert AP, Anderson BJ, Martinsen OG, Hammerschlag R, Cina S, Wayne PM and
Langevin HM 2008 Electrical properties of acupuncture points and meridians: a systematic
review Bioelectromagnetics 29 4 245-256
[3] Fukumoto T and Akiyama H 2010 Acupuncture point position evaluating apparatus US Patent
7,818,054
[4] Reichmanis M, Marino AA and Becker RO 1977 Laplace plane analysis of transient impedance
between acupuncture points Li-4 and Li-12 IEEE Trans. Biomedical Engineering 4 402-405
[5] Ahn A C and Martinsen O. G. 2007 Electrical characterization of acupuncture points: technical
issues and challenges The journal of alternative and complementary medicine 13 8 817-824
[6] Becker RO, Reichmanis M, Marino AA and Spadaro JA 1976 Electrophysiological correlates of
acupuncture points and meridians Psychoenergetic Systems 1 106 195-212
[7] Johng HM, Cho JH, Shin HS, Sah KS, Koo, TH, Choi SY, Koo HS and Park MS 2002
Frequency dependence of impedances at the acupuncture point Quze (PC3) Eng. Medicine
and Biology Magazine IEEE 21 2 33-36
[8] Rosendal T 1944 Further Studies on the Conducting Properties of Human Skin to Direct and
Alterting Current Acta Physiologica Scandinavica 8 2-3 183-202
9th International Fr¨
ohlich’s Symposium IOP Publishing
Journal of Physics: Conference Series 329 (2011) 012034 doi:10.1088/1742-6596/329/1/012034
9
... One reason that TENS provides less pain relief may be related to high skin impedance that prevents ES from penetrating deeply enough to stimulate painful areas in tendonitis. is shortcoming may be overcome by the more conductive and deep-penetrating TPRF [13,14]. ...
... So, the higher the stimulation frequency, the lower the capacitor impedance. Since TPRF has a much higher frequency, TPRF therefore is more conductive and has a deeper penetrating energy than TENS [13]. It also explains why the low-frequency TENS can only conduct through the skin while the high-frequency TPRF conducts through both the skin and deeper tissue and reaches more neuronal fibers, resulting in better pain relief. ...
... 59.13 ± 9.47 12.73 ± 5.79 * 16.73 ± 4.47 * * 19.26 ± 3.37 * * * 21.13 ± 3.81 * * ...
Article
Full-text available
Objective To compare the safety and efficacy of 2 transcutaneous stimulation techniques, transcutaneous pulsed radiofrequency (TPRF) versus transcutaneous electrical nerve stimulation (TENS), in chronic shoulder tendonitis. Design A prospective, randomized, and double-blind clinical trial. Setting Academic pain service of a city hospital. Subjects Fifty patients with sonography-confirmed shoulder tendonitis. Methods Fifty patients were randomly allocated into two groups for electrical stimulation treatment with 3-month follow-ups: Group 1 (n=25), TENS and Group 2 (n=25), TPRF. Both groups underwent either treatment for 15 minutes every other day, three times total. Our primary goals were to find any treatment comfort level, adverse event, and changes in Constant–Murley shoulder (CMS) scores. The secondary goals were finding the changes in pain, enjoyment of life, and general activity (PEG) scores. Results For primary goals, no adverse events were noted throughout this study. No differences were found between groups for treatment tolerability (3.20 + 0.87 vs. 2.16 + 0.75). Statistically significant lower PEG scores were noticeable with the TPRF group after the course (12.73 + 5.79 vs. 24.53 + 10.21, p=0.013). Their statistical significance lasted for 3 months although the difference gap diminished after 1 month. CMS scores were significantly higher in the TPRF group (70.84 + 6.74 vs. 59.56 + 9.49, p=0.007) right after treatment course but the significance did not last. Conclusions In treating chronic shoulder tendinitis using two transcutaneous stimulation techniques, both TPRF and TENS are safe and effective. TPRF is superior to TENS.
... Second, concern exists about the material used in the gel which may [18], and metal spikes [3][14] to establish the ionic-electronic interphase with the skin. The previous paper also adapted inkjet-printing technology into bio-signal sensing application and fabricated wearable electrodes [9]. Each type of electrodes has its own distinct features and is respectively suitable for different application scenarios. ...
... Isolated by cloth or other dielectric layer, this type of electrodes can also be used for non-contact capacitive bio-signal measurements [5]. In a previous work, we proposed inkjet printed electrodes (PrintE) on paper [9] and polyimide (PI) [6]. Compared with other manufacturing methods, inkjet printing technology features multi-substrate compatible, Roll-to-Roll and mask-free (µgreen ¶ and low-cost), digital and additive (easy and cheap to customize electrode patterns according to different requirements). ...
Conference Paper
Full-text available
Driven by the increased interest in wearable long-term healthcare monitoring systems, varieties of dry electrodes are proposed based on different materials with different patterns and structures. Most of the studies reported in the literature focus on proposing new electrodes and comparing its performance with commercial electrodes. Few papers are about detailed comparison among different dry electrodes. In this paper, printed metal-plate electrodes, textile based electrodes, and spiked electrodes are for the first time evaluated and compared under the same experimental setup. The contact impedance and noise characterization are measured. The in-vivo electrocardiogram (ECG) measurement is applied to evaluate the overall performance of different electrodes. Textile electrodes and printed electrodes gain comparable high-quality ECG signals. The ECG signal obtained by spiked electrodes is noisier. However, a clear ECG envelope can be observed and the signal quality can be easily improved by backend signal processing. The features of each type of electrodes are analyzed and the suitable application scenario is addressed.
... • Strictly isolated depression of impedance modulus surrounded by circular patterns was not found in most of the maps, however in some cases there was clear indication of it (Fig.2) [4]. ...
... For the need to measure impedances above 1 MHz, 21,22 the proposed system still falls short. Compared to the devices used in other studies, 2,[4][5][6][7][8][9][10][11][17][18][19][20][21][22] our system has the advantage of being able to measure BSA MFI exactly and simultaneously. ...
Article
Full-text available
Devices which can obtain comparable bilaterally symmetrical acupoints (BSA) multifrequency impedances (MFI) are often needed in the detection of the energy balance states of acupoints in traditional Chinese medicine. To satisfy these needs, a two-channel impedance measurement system has been introduced which is capable of accurately and simultaneously measuring BSA MFI. The system includes a set of five electrodes, two of which are injected with exciting current signal to synchronously and equally excite BSA; the other three electrodes are used as sensors to simultaneously sense the response signal from both sides. The system also includes a PC-based time-domain signal testing platform with arbitrary current waveform generation and three channels (one exciting current and two response voltages) simultaneously sampling, and a set of MFI simultaneously unbiased computing algorithms based on special odd multisine current signal input. Preliminary validating experiments suggest that the system allows accurate and synchronous measurement of BSA MFI at least in the frequency range of 10 Hz to 60 kHz, and the obtained BSA MFI are well comparable.
Article
The paper deals about design and realization of context aware mobile health network system for remote diagnostic and monitoring the vital function. There were realized standalone system for significant biological data measurement and processing. The unit communicates with the peripherals or share point by ZigBee technology with secured communication. There are wide range of connection for example to mobile phone for large distance monitoring and localization.
Conference Paper
This work was focused on measurement of the mechanical properties of surgical incision on leather treated with tissue collagen glue. The work is focused to find the relationship between acting force and strain on the leather specimen with glue contact using optical method. The traditional contact strain analysis during tensile test cannot be applied for measuring the skin samples. Therefore the digital image correlation technique was taken into analysis for measuring object deformation. This technique is capable of correlating digital images of studied object before and during experimental test deformation to determining displacement and strain of the object based on corresponding position on the image. In this work, this technique is applied to analyze the mechanics of skin samples tensile test.
Conference Paper
The content of this article is to describe how to achieve the highest possible code for the ARM Cortex processor-type M. This paper is focused on describing the implementation of the code in assembler language programming. Currently, programming in assembler language, rarely used, but there is still a group of tasks where the use of low-tier approach still used. A typical example is the development of software for battery-powered medical devices with high reliability.
Article
Full-text available
Acupuncture points are frequently described as having distinct electrical properties. These properties include increased conductance, reduced impedance and resistance, increased capacitance, and elevated electrical potential compared to adjacent nonacupuncture points. Commercial electrodiagnostic devices have used this assertion as a means to localize and analyze acupuncture points for diagnostic purposes. Yet, the electrical characterization of acupuncture points is associated with important technical issues that are often overlooked. Electrode polarizability, stratum corneum impedance, presence of sweat glands, choice of contact medium, electrode geometry, and other factors contribute to the final electrodermal reading and may cause doubts about the validity of available electrodiagnostic devices. The goal of this review is to help researchers and clinicians understand these factors affecting electrodermal readings, to make apparent the difficulties and challenges confronting electrodermal readings, and to increase understanding about how these possible associations can be interpreted and understood from the perspective of biology.
Article
Full-text available
According to conventional wisdom within the acupuncture community, acupuncture points and meridians are special conduits for electrical signals. This view gained popularity after anecdotal reports and clinical studies asserted that these anatomical structures are characterized by lower electrical impedance compared to adjacent controls. To ascertain whether evidence exists to support or refute this claim, we conducted a systematic review of studies directly evaluating the electrical characteristics of acupuncture structures and appropriate controls. We searched seven electronic databases until August 2007, hand-searched references, and consulted technical experts. We limited the review to primary data human studies published in English. A quality scoring system was created and employed for this review. A total of 16 articles representing 18 studies met inclusion criteria: 9 examining acupuncture points and 9 examining meridians. Five out of 9 point studies showed positive association between acupuncture points and lower electrical resistance and impedance, while 7 out of 9 meridian studies showed positive association between acupuncture meridians and lower electrical impedance and higher capacitance. The studies were generally poor in quality and limited by small sample size and multiple confounders. Based on this review, the evidence does not conclusively support the claim that acupuncture points or meridians are electrically distinguishable. However, the preliminary findings are suggestive and offer future directions for research based on in-depth interpretation of the data.
Article
Full-text available
AC impedance between two acupuncture points (Li-4 and Li-12) and two pairs of anatomically similar points with the same separation was studied via Laplace plane analysis of the time domain current response to a predetermined voltage perturbation. The series resistance between the two acupuncture points was found to be significantly lower than between either pair of control points. The characteristic impedance of an equivalent transmission line was lower and the signal propagation velocity higher for the acupuncture point system as compared to both controls.
Article
The resistance of 4.9 cm ² of the stratum corneum to direct current (2 volts), when inorganic salt solution is used as contact electrolyte, is found to be lower at cathodic conduction ¹ where inorganic anions pass into the stratum corneum than at anodic conduction ¹ where inorganic cations pass into the corneous layer. A rise in the concentration of the contact electrolyte, or in the valency of the cations — both changes producing an increase in the concentration of the inorganic anions of the contact electrolyte –leads to a further reduction of the resistance at cathodic conduction, while the resistance at anodic conduction is not changed. Measurements of the potential across the stratum corneuni before, during and after conduction of direct current, with anodic and cathodic direction, indicate that the greater resistance to anodic conduction is not due to electrolytic polarization. Determination of the a. c.‐resistance at 200 and 2 000 cycles after anodic and cathodic d. c.‐conduction shows that the difference in resistance to the two directions of current is due to a different conductivity of the stratum corneum. The different conductivity is caused by the fact that the stratum corneum is morp permeable to inorganic anions than to inorganic cations. It is assumed that the reason is that the stratum corneum, like other organic membranes, is positively charged.
Article
Investigates an equivalence circuit model for characterizing a person's electrical properties. It is not straightforward to compare skin-impedance data of various research groups because the impedance depends very sensitively on measurement conditions such as the shape, size, material, and contact pressure of the electrodes, the skin humidity due to sweat, the applied current, the shape of the wave, and even the psychological condition of the subject. With these subtleties in mind, we show the impedance data taken by various groups and our data (shown with curves). Data of other groups are scattered around our curve.
Acupuncture point position evaluating apparatus US Patent 7
  • T Fukumoto
  • H Akiyama
Fukumoto T and Akiyama H 2010 Acupuncture point position evaluating apparatus US Patent 7,818,054
Skin resistance vs. body conductivity Frontier Perspectives
  • Cl Zhang
Zhang CL 2002 Skin resistance vs. body conductivity Frontier Perspectives 15-25