Institute of Electrophotonics, Berlin
All users of GDV technologies know that the GDV Cameras supplied by “Biotechprogress” company (St. Petersburg) can evaluate the stress level of the examinee. Evaluation is performed by a repeated measurement of finger glow of the examinees with a GDV Camera Pro using filters: the film made of special polyethylene is placed on the electrode during capturing, and further data processing is done in the GDV Diagram . The program determines the difference between finger glow images of two captures and calculates the Activation coefficient by scale from 0 to10. The examinee’s stress growth increases the electric resistance and skin perspiring thus resulting in the decrease of current of the Camera discharge and leading to a finger glow decrease. In  we see the correlation of finger glow captured without filter with the current psychophysiological state of the examinee, his nervous-psychical state.
The role of filter in  is to cut off “perspiration, sweating, excreted gases like a surgery glove put on one’s hand and thus cutting off the most part of the influence of autonomic nervous system”. This assertion repeated by the majority of GDV users is actually incorrect, and let us see why.
The sliding surface discharge used in GDV cameras emerges, by definition, on the surface; i.e. when measuring without filter on the glass surface, and when measuring with filter on the filter surface placed on the glass surface. The discharge develops between the skin tissues of the examinee’s finger placed on the glass surface or between filter and the surface of glass or filter (fig.1).
Thus measurements with filter also show the influence of “perspiration, sweating and excreted gases” on the discharge sliding over the surface of the polyethylene film-filter. If instead a finger we place the metal cylinder (GDV test object) on the electrode and capture the glow around the test object without filter and with filter, we will register the glow increase when the test object is placed on the filter. Fig.2 shows these test results obtained with a GDV Camera Pro. The total intensity of the plasma discharge glow was evaluated: the glow area multiplied by the specific intensity parameter. This parameter logically corresponds to the flow of glow photons recorded by the CCD matrix of the web camera of the GDV recorder.
The double test results are obvious: 1.The state of the object is the same, however, the glow around it is stronger when capturing filter and weaker when capturing without filter; 2.There is a good repeatability of the results.
Figure 3 shows average values of GDV parameters of 30-pulse test object glow series: a) – area, b) – average intensity, c) – total intensity.
The average values of glow parameters with filter (blue, brown) calculated in the SciLab program are higher than those without filter. Note that if during the second test the glow area decreases (brown), its average intensity increases, and vice versa (green). The reason for this, if the current of the discharge chain is unchangeable, may be the change of the electric field distribution above the electrode caused by the distribution change of the ionization level in space and the change of the surface state. It means that the glow intensity parameter correlating with the current of the discharge chain is subjected to smaller fluctuations than the area and average intensity, and thus better corresponds to the state of the object under study and discharge space.
The glow discharge registered by the CCD matrix on the film surface has to be lower than the glow registered without film because the film transparency is lower than 100%, i.e. the film decreases the photon flow. However practice shows the opposite. Why does it happen?
The answer to this question can be found in the works of late 70-ies and 80-ies dedicated to studies of powerful pulsed gas lasers [5, 6]. A sliding discharge was used for efficient gas ionization in the interelectrode space and (or) for creating plasma electrodes. It was observed that an organic material used as a surface (lavsan, getinax, etc.) improves the discharge homogeneity, and the power of the laser beam increases. References [3, 4] present spectra of an ordinary spark discharge and the discharge sliding over an organic dielectric surface, with equal specific energy contributions (fig.4). It was found that in the vacuum UV region the intensity of spectral lines is up in the order of magnitude in case of the sliding discharge.
It is shown in  that the growth of spectrum intensity within vacuum UV region is mainly due to excitation of carbon atoms in carbon-containing electrode surface by the sliding discharge which leads to additional ionization of discharge avalanches, homogeneity improvement, and, consequently, to an increase of discharge glow intensity. In our case the polyethylene film used with the GDV Camera contains carbon atoms and thus increases the glow discharge on the surface.
Thus the polyethylene film works not as a filter but rather as a compensator of the stimulation of the discharge by the change of the electric skin impedance due to the activity degree of the sympathetic part of autonomic nervous system and makes it possible to evaluate the processes in the examinee’s body in the absence of stressors (stress-causing stimuli).
Recently it was proposed to evaluate the activation of sympathetic activity by calculating the difference between the measured glow without filter and the specified glow of the metal cylinder (test object) . Is it true?
The finger glow level depends on the galvanic properties of the examinee’s body and may come close to the test object glow value and even exceed it .
I.e. two people with different galvanic properties and different stress states may have, in this calculation, the same GDV stress parameters (activation coefficients). It means that such approach is erroneous.
- The polyethylene film used in GDV measurements increases the plasma discharge glow around the object under study and in case of evaluating human stress level is not a filter but rather a compensator of the changes caused by the activity growth of the sympathetic part of autonomic nervous system.
- The “total intensity” parameter shows smaller fluctuation than the area and average intensity thus it better describes the state of the measured object and the states of the discharge space.
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GDV Workshop. Saint Petersburg, July 2013., Presentation of the "Bio Well" system.