Experiment Name: Field Mapping of E-Field in a Salt Water Tank
Experimenter(s): Uncle Abdul
Date(s) Performed: 10 - 20/January. 1999
Location(s) Performed: Khabarovsk, Russia
Experiment Purpose: To study the various claims of TENS users on a first approximation simulation of the body's inner core. The claims studied will be--
Theory: In the human body the skin (epidermis layer) exhibits a relatively high electrical resistance of approximately 50,000 (50K ohms) to 1,000,000 (1Meg ohms) as measured with an ohm-meter. The interior or the body, however, exhibits a far lower resistance depending on the various components. Blood and urine exhibit about a 2,000 to 10,000 ohm resistance (as measured by an ohm-meter)--approximating that of a salt water solution. While the body does not exhibit a uniform resistance, for experimental purposes we can assume a worst case scenario of a uniform 2,000 ohm resistance. This would then be a first order approximation of the actual body interior.
This approximation is not without its justification. Certainly as blood has a resistance of this order and seeing that it is possible to actually make physical contact with the blood during play, then this approximation would hold more than it would not. Also since the bloodstream is always in intimate contact with the heart, a study based on such a conservative model would more assume a more critical importance.
Approximation models have long been used in engineering and science to get a first approximation answer to the more complex systems that occur in nature. In electrical engineering curricula, laboratory experiments are often used to demonstrate to the student the conceptual ideas of fields. Thus iron filings sprinkled on a sheet of paper placed over a magnet demonstrates a concept of magnetic flux. The pattern of filings do indeed follow the flux field, but are only approximate and are not really used to measure the intensity and spatial properties of the magnetic field with the same precision that can be obtained with more precise measuring instruments.
Electric fields can also be thus visually demonstrated in the laboratory using 'Toleadus Paper,' a special paper that has a conductive surface. Thus imposing an electric field in some spatial configuration, the resultant electric field can be 'mapped' by measuring the voltages at different coordinates throughout the paper's surface. The salt water tank experiment described below is based on such a field mapping principle.
Field mapping is not the only way that a picture of an electric field can be developed. With the advent of modern computers equivalent circuits consisting of mesh models of linear, non linear, uniform and non-uniform impedance matrices can be set up and investigated. Normally this calls for the employment of a technique known as the 'relaxation method.' Ultimately this may be the key to finally answering the question of "electrical play above the waist." Such a model, however, by the complex nature and the spatial granularity of the body interior system would possibly require an enormous computing capacity such as seen in a mainframe computer. Such a model once set up, however, can be tested by comparing the computational results of the tank experiment with the actual measured data shown herein. A properly configured computer model should show excellent agreement with the experimental results shown here. So there is a value of this experiment even in more precise and meaningfully modeled ones.
In using an ionic bath such as proposed one begins to observe the various phenomenon associated with currents flowing through such media. To understand these phenomenon one must get a clearer picture of the nature of currents in ionic solutions.
Current itself is the movement of various charged bodies, either positive "+" or negative "-" in some matrix be it the metal of a wire, the charged plasma of a gas, or the ions in an ionic solution.
In a metallic conductor the current, caused by the imposition of an electric field or a changing magnetic flux, is the flow of those 'loosely held' electrons in the outer shells of the atoms of the conductor. When so separated from the atomic core these electrons are called free electrons. The remaining, positively charged ions in the conductor consisting of the remaining atomic parts, i.e., the nucleus and the remaining electrons are vastly heavier than the electrons separated from it, and hence move hardly at all if at all.
Contrasting to this action an ionic solution not only has free electrons but also has charged atomic components called ions. These ions usually exist in both positively charged and negatively charged simultaneously in the solution. The ions are really atoms that have either an excess of electrons (hence negatively charged) or a deficiency of electrons (hence the positive charge). These ions are also relatively more mobile in an ionic solution than in a metal. Hence their movement can contribute to the current observed.
As in the case of the metal conductor, the ability of the voltage to contribute to the stripping of the electrons from the atoms in an ionic solution is dependent on the magnitude of the voltage itself.
In a metal then, if an extremely large sheet where the length and width of the conductor were many times more than the thickness, then it would be observed that most of the current would exist in a relatively narrowly confined path about the shortest path between the poles of the applied voltage. In such a 'sheet conductor' thus described and using a voltage source of say 1-1/2 volts with a path length of 10 cm or so, most of the current would be seen flowing about the path and hardly any seen about 1 mm or so either side of the prominent current path.
This same action would be expected to be observed in an ionic bath. However, because other charged bodies can be involved in the current, the extent of the electric field's effect can be more far reaching than in a metallic conductor of equivalent dimensions. It really depends on the atomic composition of the materials involved.
For both situations, however, the following generalizations can be expected.
Insofaras the method of selection of voltages, etc. is done, it must observe the practicality associated with the availability of equipment. Normally in a E-Stim or E-Play situation the voltages present at the interior of the body, i.e., below the epidirmal skin layer, would be of the order of millivolts. However this experimenter did not have access to electrical measuring instruments capable of operating in those ranges, so an experimental compromise of sorts had to be reached. Using voltages of 1-1/2 to 6 volts and a regular VOM, a sufficiently measurable field could be achieved in the salt bath. In an attempt to reduce it to a more general situation, all raw experimental data was converted to 'per unit,' i.e., the measured voltage was divided by the voltage appearing across the terminals. For a given terminal voltage, albeit higher than those that would be seen for the E-Stim/E-Play situations, the conditions would become stable for conditions of voltage, ion concentration, and spacing of electrodes. Thus the bulk resistance of the ionic solution could be considered as constant and uniform throughout. Hence per unit voltage differences existing spatially within the salt tank would result in per unit currents flowing between those spatial points per Ohm's Law. The results thus obtained and thus reduced would be demonstrate the theoretical points noted above and would, thereby, be of use to the questions at hand and for E-Stim/E-Play specifically.
Experimental Setup: A shallow (relatively), transparent, and approximately rectangular dish is filled with a salt water solution. Beneath the dish is a spatial grid having lines spaced every 1-inch (25.4mm) and running longitudinally and laterally to the dish. Electrodes are placed at the periphery of the dish in various configurations. The electrodes are then connected to a battery to impose an electric field in the conducting medium, i.e., the salt water solution. A voltmeter is then used to measure the voltages at the intersections of the spatial grid and referenced to one of the electrodes (generally the electrode connected to the negative, "-", pole of the battery. The data thus measured is recorded and mapped.
Equipment Used: (Equipment notes shown thusly: (#). )
Equipment Commentary:
Experimental Procedure:
Preparation of the Salt Solution Prior to the performance of the experiment the salt solution was prepared. Using an 8-cup plastic measuring cup ordinary room temperature tap water was placed therein. Then salt was added and stirred into solution until it reached a saturation condition for that temperature. This was evidenced by some salt particulate remaining at the bottom of the container.
Preparation of the Salt Tank The salt tank container was placed on the grided paper and aligned so that center of the container (as evidenced by the injection molding sprue) coincided with the '4-F' intersection on the grid. The container was then aligned so that it was square and equidistant on the grid. (This gives a spatial grid marked A to K in the longitudinal, 'X', direction and 1 to 7 in the transverse, 'Y', direction within the confines of the container. Note that all axes markers are away from the sides of the container. The origin of the coordinate system (at '1-A') thereby achieved did not intersect the corner of the container. All walls were within 25 mm of the outer axes.)
The electrodes were then attached to the sides of the container using the wooden clothespins in one of the configurations shown below. These electrodes--iron nails--were pre-attached to wire leads. Only one of the leads was attached to a battery post.
A 4-cup transfer container was used to transfer the saturated salt water solution to the salt tank. The solution was decanted so that only solution was transferred and none of the salt precipitate. The tank was filled until the depth of the solution measured 3/4-inch or 20mm from the bottom of the salt tank.
Preparation of the Electric Circuit All leads were checked. External dropping resistances if used were connected and checked. Then a test connection was made by connecting to the final pole of the battery. The electrodes were checked and it was noted whether there was gas evolving from the negative electrode. Then the battery was disconnected at one pole immediately prior to the start of the measurements.
Measurements Before starting with the mapping measurements the VOM was setup in current measuring mode using the 250 milliamp DC measurement scale. Thus the current to or from an electrode was measured.
Next the battery was hooked up and the VOM set to the 0-5 VDC scale. The voltage across the electrodes was then measured. With this current and voltage measurement the tank's bulk resistance could now be measured.
The measurement of the electrical voltage field within the salt tank was then made. The negative probe of the VOM was attached to the negative electrode at the tank and thus represented the 0-volt reference. The positive probe of the VOM was then inserted into the salt water solution, placed at the intersection of the grid axes, and aligned roughly vertically. The voltage reading was made and recorded. The probe was then moved on to the next coordinate on the grid. Always the grid was traversed from coordinate 1-A to 7-K in order from 1-A, 1-B,..., 1-K, 2-A,... etc. to 7-K.
After all 79 measurements were made and recorded, the battery was disconnected. The salt tank was then visually examined and observations were recorded. Because of the deposition of various iron salts along the predominant current path(s), the old solution was discarded and the container rinsed and dried before another setup was made.
Configurations The following experimental configurations were used for measurement purposes:
Experimental Data (Raw):
The voltages and currents and other observations are recorded as follows:
Experimental Data (Reduced):
Methodology Employed in Data Reduction The raw experimental data was reduced using a Texas Instrument, Extensa 575CD laptop computer using MS Works spreadsheet software.
The first order of reduction was to reduce the measured voltages to 'per unit' values. Assuming the negative electrode as always being at 0-volts or 0%, all other voltage values were divided by the voltage appearing at the positive electrode--again as measured using the negative electrode as the 0-volt reference. These reductions were done using functions on the spreadsheet software.
The next order of reduction was to try to come up with a determination of the possible currents that may exist at the various coordinates. Working on the basis that for a given set of salinity and voltage conditions the resistance across the same distance would be constant and uniform throughout the salt tank, then the currents could also be expressed in 'per unit' terms. We can now think of each coordinate as representing the center of a volumetric cell of dimensions 25mm x 25mm x 18mm. Using the simplifying approximation that all other adjacent cells are equidistant from the cell of interest (thereby eliminating necessities for the introduction of trigonimetric spatial distance compensation), it can be said that each cell is surrounded by 8 neighboring cells of the same form and dimensions. Each of these neighboring cells has its own voltage. Therefore by doing a vector summation of the voltage differences from the cell of interest to each of its neighboring cells (i.e., Kircchoff's Law) then you can have a voltage difference summation that has magnitude and direction. Since expressed in 'per unit' values, this would also represent the 'per unit' current existing at the cell of interest. Therefore, using this methodology, a map of the possible current flows in the salt tank can be estimated.
Some conventions were necessarily employed in this methodology. Firstly, conventional current was used, i.e., current flows from + to -. Next, the calculations for each cell was done on the basis of always considering the neighboring cells in the following order: starting with the neighboring cell in the corner above and to the left as No. 1, then the other cells are numbered in ascending numerical order clockwise to No. 8, that being the cell that is immediately to the left of the cell of interest designated as cell No. 0 (see chart below). Therefore directions are easy to calculate being either signed in the X or Y direction, or in the case of cells 1, 3, 5, and 7, require only the division by the square root of 2 to determine vector components. The resultant X and Y magnitude components can then be used to calculate the resultant magnitude by using the square root of the sums of the squares. The phase angle of the current is done by taking the arctangent of the X and Y magnitude components. All of this can be easily and rapidly done using the spreadsheet software.
| 1 | 2 | 3 |
|---|---|---|
| 8 | 0 | 4 |
| 7 | 6 | 5 |
To prepare the necessary maps for the voltage fields and estimated current flows, the reduced data was then color coded in each cell. The colors were roughly selected on the R-O-Y-G-B-I-V acronym (spectrum colors) where R, red, is the highest value. Black is the color designation for 0%, i.e., the battery's negative terminal. 10% bands were used to assign colors.
The voltages and currents were reduced and shown as follows:
Conclusions: Even though the number of cases studied in this experiment, the following general conclusions can be drawn:
Interpretation of Experimental Results: It appears from the experimental data and noting the limitations of the experimental proceedures and assumptions that a rough hierarchy of the danger of the experimental configurations studied can be thought of in the following manner:
from MOST DANGEROUS
to LEAST DANGEROUS (but still not absolutely safe)
© by Uncle Abdul, 1999. No copies
-hardcopy or electronic-may be made without expressed, written permission of the author. This material is presented for informational purposes only and is not represented as nor should it be interpreted as a standard, a specification, a recommended practice, a guideline, or even a professional opinion on the safety of C/BDSM or of any equipment or systems. The author cannot be held responsible for nor does he certify the safety of any equipment or devices that are built, designed, and/or manufactured utilizing this information. In the nature of a textbook the author requests comments on omissions and errors that a reader may find contained herein. The author can be contacted at UncleAbdul@gMail.com.