SU1296114A1 - Apparatus for determining active component of skin electric resistance - Google Patents

Abstract

The invention makes it possible to enhance; the accuracy of measurement of the active component of the electrical resistance of the skin by compensating for the influence of the electromotive force of the polarization of the electrodes. This is achieved by using a double field of current pulses and measuring the instantaneous value of the voltage between the electrodes at the time of termination of every second current pulse with the help of sampling-storage elements. The device contains a generator of two bipolar current pulses, a generator of 2 clock pulses, switch 3, patient electrodes 4, amplifier 5, two half-half 1st rectifier 6, sampling-storage units 7 and 8, resistive load 9, two analog switches 10 and 11, a low-pass filter 12 and a measuring unit 13. 2 silt (/ C

Description

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The invention relates to medical technology and can be used in conducting electrophysiological and neuropsychiatric studies.

The purpose of the invention is to improve the accuracy and speed of measurements in the low frequency region.

Fig, 1 shows a block diagram of the device; in fig. 2 - stress diagrams at characteristic points of the circuit.

The device contains a generator of 1 bipolar current pulses, a generator of 2 clock pulses, a humidifier 3, electrodes 4 of the patient, an amplifier 5 full-wave rectifier 6, blocks 7 and 8 sampling-storage, an active switch 10 and 11, filter 12 the lower frequencies and the output measuring unit 131 o

The device operates as follows:

The generator 1 of bipolar current pulses is triggered from the generator 2 of the clock pulses and produces current pulses that are strictly the same in terms of a fflity and duration, but of different polarity. The duration of these nyjibcoEs is determined by the frequency of the tacho and fflyls (practically it does not exceed 1 s), and can be easily changed if necessary. Such a duration is sufficient for the transient process due to the internal nets, new equivalent capacitances to the end of each pulse, to end, and the instantaneous voltage on the electrode and accuracy would correspond to the active component of the electrical resistance of the skin if not. There was an emf of electrode polarization. Since the increase in polarization electromotive voltage at current supply and for a time equal to the duration of the iG Shulce t does not stop (Fig. 2), a change in the polarity of the pulse to the reverse also causes a change in the direction of polarization begins to subside, and after a time tg equal to the time t of the previous pulse, it becomes zero. Thus, at the end of a pulse of opposite polarity (t, e, at the end of the period of a bipolar pulse), the result of the polarization emf will be fully or substantially compensated. Therefore, in this

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the instant of time, the instantaneous value of the voltage across the electrodes is determined only by the active resistance of the skin, more precisely, by its current value. Plots 1) 4 (Fig. 2) show the voltage pattern at the patient's electrodes, while the distortion of the leading edge of the pulse is determined by transient interstitial processes, and the distortions of the site are due to the influence of the electromotive force polarization of the electrodes.

At the output of the amplifier 5, the shape of these pulses is repeated, and at the output of the full-wave rectifier, a signal U arises (Fig. 2). Sampling-storage units 7 and 8 are controlled by the voltage voltages U and Ug of the switch 3 (direct and inverse outputs), while the pulse duration is exactly twice as long as the pulse duration Ut. If block 7 first. operates in the sampling (tracking) mode, since a positive signal U is fed to its controlled input and a U signal appears at its output, then at the same time, block 8 is operating in the storage mode, since zero appears at the control input the signal is U. But since at the beginning of work at the input of block 8 there is no voltage, it will not be at the output of this block, further diagrams U and Uo show

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forms of voltages at the outputs of both blocks of the sample-storage.

The control inputs of the analog switches 10 and 11 are connected in opposite phase. Therefore, on an active grounded load 9, the signal appears only if the corresponding sampling unit 7 or 8 is in the storage mode. The short peaks of voltage C are eliminated by the filter. 12 lower hours — the voltage from the output of which goes to the output-measuring unit 13. Thus, at the end of each period, the current value of the electromotive force of the polarized electrodes is compensated regardless of the change in magnitude This emf is influenced by time, electrochemical processes between the skin and the electrodes, temperature and m, n. As a result, at the output of the device, each time a new current value of active resistance of the skin is determined. The device is not critical to the choice of electrodes. It is advisable to choose metal electrodes of equal area.

Claims (1)

3 12 Claim Formula A device for determining the active component of the electrical resistance of the skin, comprising the patient's electrodes, the first sampling-storage unit, the amplifier, the switch and the low-pass filter, which is better for Nor does the accuracy and speed of measurements in the low frequency region, it additionally contains a bipolar current pulse generator, a clock pulse generator, a full-wave rectifier, a second sampling-storage unit, two analog switches, an active grounded load and meter a unit, the clock generator output being connected to the control inputs of the bipolar current pulse generator and five 15 0 144 mutator, the first output of which is connected to the control inputs of the first sampling-storage unit and the first key, and the second output - to the control inputs of the second sampling-storage unit and the second key, the output of the generator of double-pole current pulses is connected to the electrodes, the output of which through - therefore, the connected amplifier and full-wave rectifier are connected to the inputs of the first and second storage sampling units, the outputs of which are connected to the inputs of the second and first keys, respectively, the output of the first key is connected to the output the second key, the input of the low-pass filter and the active grounded load, and the output of the low-pass filter is connected to the input of the output measuring unit. . Compiled by A. Faltsman Editor E. Sligan Tehred I. Popovich Corrector V. But ha Order 644/5 Circulation 596 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, Projecto st., 4