RU2488104C1 - Method for determination of electrical characteristics and/or identification of biological objects and apparatus for realising said method - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: in the method of determining electrical characteristics and/or identifying biological objects, the biological object is subjected to electric current for a certain period of time; current and voltage values are measured; the array of obtained data is stored and the obtained array is mathematically processed, wherein current and voltage are measured at the same time the biological object is subjected to electric current, wherein the object is subjected to at least one voltage pulse with a regular rate of rising and/or falling of the voltage of at least 10⁴ V/s, preferably 10⁷-10⁹ V/s. An apparatus for realising said method is also disclosed.

EFFECT: invention provides a rapid and highly informative method and apparatus for analysing properties of biological objects.

15 cl, 15 dwg, 4 tbl, 4 ex

Description

The invention relates to methods for analyzing the physical and chemical properties of biological tissues and materials of biological origin by registering electrochemical parameters and mathematical processing of the obtained data, and can be used in the food industry for analytical control (diagnostics) and evaluating the quality and safety of food products and raw materials for them manufacturing, as well as in medicine to diagnose various diseases and assess the degree of pathological changes in tissues and organs.

Known methods for measuring the individual components of the impedance, namely the active and reactive resistances. Most of them are based on the use of high-frequency alternating current with an operating voltage of up to 12 V, for example, the method [SU No. 1759402 A1], where the measuring device includes compensation elements with variable resistance and capacitance to compensate the active and reactive components of the impedance of the test object. Such methods do not provide sufficient measurement accuracy due to the fact that it is not possible to fully compensate for the active and reactive components of the impedance of the biological tissue – current electrode system. In addition, the proposed schemes, as a rule, contain inductive elements that cause significant additional errors and do not allow measuring the tissue’s own active resistance.

A known method for determining the quality of food products described in the patent of Great Britain [GB No. 2288022 A]. Its essence lies in the fact that electrical impulses having 3 or more harmonic Fourier frequency components are applied to the test object, the animal’s meat, and current or voltage are measured in the time and / or frequency domain. And they compare the characteristic features between the found and known response, from which they conclude about the quality of the food product.

The disadvantage of the method according to the patent [GB No. 2288022 A], selected as a prototype, is that the transmission of high-frequency current through the test object is carried out until the measurement. Therefore, the cells are not in real, but in an altered state, since biological systems have the ability to accumulate electric charges.

In the measurement results obtained by the method described in [GB No. 2288022 A], inevitably there will be errors in the measurement of electrical parameters associated with the temperature of the sample, since the impedance of biological tissues is a function of temperature. In addition, the use of voltage pulses with low amplitude leads to the display of a rather limited amount of information, and the need to use electrical effects in several frequency areas complicates the measurement and increases their duration.

The objective of the present invention is to develop a new method for determining the electrical characteristics of biological tissues and materials of biological origin suitable for identification and qualitative analysis of the properties of biological objects.

The technical result is an express and highly informative method and device for analyzing the properties of biological objects.

The objective of the invention is solved in that, as in the known method - the prototype, a biological object is exposed to electric current for a certain time, the value of currents and voltages is measured, the array of received data is stored, and the resulting array is mathematically processed.

New in the proposed method is that the measurement of currents and voltages is carried out simultaneously with electrical action on a biological object, while electrical action is carried out by at least one voltage pulse with an adjustable value of the rate of rise and / or fall of the voltage of at least 10 ⁴ V /from.

Preferably, the slew rate and the sink rate are 10 ⁷ -10 ⁹ V / s.

In this case, the electric current is carried out either by a single pulse or by a group of single pulses.

In the case of using a group of pulses, their transmission is carried out with a frequency lying in the range of 0.5-10 Hz.

Preferably, when exposed to a group of pulses, their transmission frequency is 0.8-2.0 Hz

The pause time between pulses in the group should be sufficient for the relaxation of biological tissue i.e. in order to return it to the state that existed before the electric action, therefore, in the case of using a group of pulses, they are transmitted at a frequency of not more than 10 Hz. Such an organization of electrical exposure also avoids the catastrophic heating of biological tissue. The minimum frequency value is 0.5 Hz. The transmission of pulses with a lower frequency will lead to an increase in the duration of the measurements and complicate the registration of the electrical signal by an analog-to-digital converter.

Use voltage pulses with the following parameters:

- pulse shape: trapezoidal, triangular, preferably symmetrical triangular;

Preferably, the duration of the trapezoidal pulse (the base of the trapezoid) is 5-300 μs.

Preferably, the duration of the triangular pulse (the base of the triangle) is 5-300 μs.

The amplitude value of the voltage for trapezoidal and triangular pulses is up to 1000 V.

Preferably, the amplitude value of the voltage for trapezoidal and triangular pulses is 90-300 V.

The specific parameters of the pulsed electrical action are selected depending on the properties or type of the particular test object.

The minimum value of the pulse duration of 1 μs is due to the fact that this value corresponds to the minimum required time for the process of current flow through the biological tissue to become steady state.

Increasing the pulse duration above the maximum declared value of -800 μs leads to significant destruction of the tissue, as well as to its local overheating and gas evolution, which reduces the information content of the measurements.

It is preferable that the system for measuring electrical parameters contains at least one invasive reference electrode placed in a bioobject in the space between the current-carrying electrodes.

The use of an invasive reference electrode allows direct measurements of the polarization voltage U _p at the interface between the invasive electrode (anode / cathode) - biological material.

It is preferable that the current flowing through the test object be measured by a current-voltage converter, which is a Hall sensor or a resistive shunt.

Through the use of voltage pulses with the declared values of the amplitude and slew rate, it becomes possible to determine the magnitude of the active component of the impedance and, more importantly, the capacitive part of the resistance.

It is important to note that these exposure parameters are implemented for a load whose resistance has an exclusively active component. For such complex objects, which are biological tissues and materials of biological origin, the impedance has both active and reactive components, therefore, the nature of the increase and decrease in voltage at the test object may not correspond to the output voltage parameters of the device performing electrical exposure. Thus, it was established that the nature of the rise and fall of both current and voltage in a real test object is a reflection of its properties.

Additionally, before electric exposure, sample preparation is carried out, which consists, for example, of keeping the sample and invasive electrodes in an air thermostat at a temperature of 20 ° C until they reach the indicated temperature.

Preferably, the ratio of the cathodic and anodic current density during electrical exposure is in the range from 1: 1 to 10: 1.

In addition, to identify biological objects and their state, mathematical processing is carried out by comparing the resulting data array with the arrays obtained for the known state of the biological object, and based on the comparison, a conclusion is drawn about the type or condition of the biological object.

If the test object is food or raw materials for their manufacture, then to determine the quality indicators, the test object is exposed to electric current, the current values and voltage drops are measured, the array of received data is stored and the data obtained is compared with the arrays obtained for the test objects with well-known quality indicators, on the basis of the comparison, make a conclusion about the quality of the food product.

The task is also achieved by the fact that the inventive device for determining the electrical characteristics of biological objects contains a test signal generator configured to control the rate of rise and / or fall of the output voltage, electrodes for supplying voltage to the biological object and measuring the electrical characteristics of the object, a measuring module (system ), a computer for controlling the generator of test signals, storing and processing data arrays of electrical characteristics stick

The measuring module is configured to coordinate current and voltage in time.

The measuring system can be made two-channel, in which the first channel contains a voltage divider connected to an analog-to-digital converter for measuring voltage, the second channel contains a current-voltage converter also connected to an analog-to-digital converter for measuring current.

The measuring system may also be three-channel, in which the first channel contains a first voltage divider connected to an analog-to-digital converter for measuring voltage, the second channel contains a second voltage divider connected to an analog-to-digital converter for measuring polarization voltage, and the third channel contains a current converter - voltage, also connected to an analog-to-digital converter for measuring current.

In addition, the test signal generator consists of the following main elements: a device for specifying the test signal shape, controlled from a computer, a power amplifier that amplifies the initial test signal to a predetermined voltage value, thereby forming a large-scale copy of it and ensuring the flow of the required current and power source .

In addition, the test signal generator consists of the following main elements: an electric energy storage unit, a power key controlled by a control device that performs the function of opening and locking the key, which allows you to control the rate of rise and fall of the output voltage of the test signal generator and its shape.

In this case, the accumulation of electrical energy in the block can be carried out by means of capacitive, inductive elements, a transformer.

In addition, the test signal generator consists of the following main elements: an electric energy storage unit, a power key controlled by a computer, and variable inductance is used to control the rise / fall rate of the output voltage of the test signal generator.

The described embodiments of the generator of test signals allow to obtain voltage pulses, for example, trapezoidal or triangular in shape with the desired rate of rise / fall of the output voltage.

Preferably, the device comprises an additional electrode, a reference electrode (10) for measuring polarization voltage.

In this case, the electrodes (9, 9 ') for supplying voltage to the biological object and the reference electrode (10) are structurally combined into a single unit - the sensor.

It is desirable that the electrodes for applying voltage were made in the form of needles for immersing the electrodes in the biological object under study.

An increase in the cathode current density with respect to the anode one allows for a longer service life of the invasive electrodes, as well as direct measurements of the polarization voltage U _p at the invasive cathode – biological material interface.

An increase in the cathode current density is achieved through the use of needles with the same dimensions as invasive electrodes, with many needles performing the function of a cathode. Cathode needles are connected in parallel, i.e. have electrical contact with each other. In addition, with such an organization of the process of electrical exposure, it becomes possible to use a reference electrode, which, as a rule, has a high cost.

Biological tissues can be characterized as second-type conductors with ionic conductivity. The presence of cell membranes, limiting the cytoplasm and intracellular structures, determines a fairly high electrical intensity of the tissue and its ability to polarize, since the membranes have high dielectric properties at a small thickness of about 10 nm. High polarization capacity is a characteristic property of living intact biological tissues [Biophysics: Textbook. B.N. Tarusov, V.F. Antonov, B.V. Burlakova and others. M .: "Higher school", 1968. 468 p. P.189, Eliseev, D.S. Automatic control of the state of plant tissue of weeds during electrical processing. Text .: / D.S. Eliseev // Mechanization and electrification of agriculture. 2004. - No. 3. - p.21-22.].

In case of damage to biological tissues, due to cell death, subsequent degradation of muscle proteins by proteolytic enzymes, as well as due to the alignment of the concentrations of sodium and potassium ions on both sides of the membrane, the tissue gradually loses its ability to polarize. Therefore, the capacitive component, for example, the impedance of meat immediately after slaughtering, has a maximum value, and with an increase in the shelf life it decreases, and at the same time the active component decreases. [Biophysics: Textbook. B.N. Tarusov, V.F. Antonov, B.V. Burlakova and others. M .: "Higher school", 1968. 468 p. P.192]. This property allows you to use the electrical characteristics of biological objects to determine their quality indicators.

The implementation of electric exposure at the claimed voltage values (up to 1000 V), in contrast to the known methods, allows to identify the begun destruction of the membranes due to their forced depolarization. Therefore, this method is compared with the known more informative (sensitive).

A breakdown of the lipid component of the membranes with the claimed parameters of the pulse voltage leads to a sharp, but short-term increase in the permeability of cells and an increase in ion fluxes, causing their reversible depolarization. In addition, the use of such an electric effect avoids the appearance of the so-called "concealing" effect due to the influence of tissue fluids, which is present in known methods and prevents the establishment of the absolute value of capacitive resistance. It is the capacitive part of the current and the dynamics of its change that objectively reflects the morphological and functional state of biological tissue, and also allows us to assess the degree of destruction of cell membranes.

Since the cell membranes of biological tissues are capable of accumulating charges, charge and recharging processes can be observed with the passage of electric current, which, depending on the nature of the biological material, are reflected in the magnitude of the current. The charge and recharge rates with a change in polarization will vary depending on the species of biological objects and the nature of the tissue, since the species structure of biological tissue cells in different species is different. The differences are related to the size of the cells, the structure of the cell membranes, the composition inside and intercellular media and, therefore, conductivity. This leads to differences in the localization of charges in the membranes and a different ratio between the values of the accumulated charges.

The electrical parameters of the test objects recorded in the claimed method are digitized with a certain discreteness and presented in the form of a large data array, from which, for example, current values, its active, capacitive, and pseudo-capacitive components can be extracted. The generated data array corresponding to a specific biological material is unique and corresponds to its state.

The coincidence of the array obtained at the test object with the array of the standard allows you to identify the biological object. The peculiarity is that for one continuous measurement cycle, an array of data is obtained, consisting of points corresponding to different conditions of electric exposure (different potentials).

Since the size of the array is set by discreteness, the accuracy of determination can also be adjusted. Thus, biological material is identified by a huge number of points obtained under different conditions, but in the process of one short measurement. A large number of points allows to increase the accuracy of material identification.

When storing biological material, its biological changes occur. This is reflected in a change in the structure of cell membranes, a change in the composition inside and intercellular media. The ability to accumulate charges and the conductivity of biological objects is changing. Such changes will lead to a change in the active and capacitive components of the current and will generally be reflected in the array of recorded data, which allows identification and determination of quality indicators of biological objects and biological materials.

Below is the rationale for the applicability of triangular voltage pulses in order to display the properties that characterize biological objects.

The use of triangular-shaped impulses for the polarization of the objects under study allows direct measurements of the current density at a given rate of change of potential.

Since the value of capacitive current is determined by the ratio:

, $$i_{\mathrm{from}}=\mathrm{FROM}\frac{dU}{dt}$$

,

where i _{with the} density of the capacitive current, A / m ² ;

C is the capacity, f;

U is the voltage, V;

t is the time, s;

then the total current density can be defined as:

, $$i=i_a+i_c=i_a+\mathrm{FROM}\frac{dU}{dt}$$

,

where i _a is the density of the active current, A / m ² .

When using impulses of the driving voltage, having the shape of an isosceles triangle, on the ascending part of the voltage, the current density is determined by the value:

, $$i_f=i_a+i_c=i_a+\mathrm{FROM}\frac{dU}{dt}$$

,

On the descending part of the voltage, the current density is determined by the value:

. $$i_b=i_a+i_c=i_a+\mathrm{FROM}\frac{dU}{dt}$$

.

The sum of the currents in the ascending and descending parts allows you to determine the value of the active current:

. $$i_f+i_b=2i_a$$

.

The difference in the values of the currents in the ascending and descending parts allows us to determine the value of the capacitive current:

. $$i_f-i_b=2i_c+2\mathrm{FROM}\frac{dU}{dt}$$

.

Since the values of current densities depending on voltage are directly measured values, and the magnitude of the rate of change of voltage is set (the slope is a characteristic of the shape of the driving voltage), it becomes possible to measure the dependence of capacitance on voltage.

Varying the rate of rise and fall of voltage in the claimed range of values allows you to select the most optimal mode for recording an array of data of electrical parameters characterizing an electrochemical system containing a test bio-object, which ensures the required accuracy and information content of the method.

Impact on biological objects with pulses with a voltage rise rate starting from 10 ⁴ V / s allows you to apply an increasing potential difference to biological material, where the process of polarization of cell membranes has already been launched. Thus, it becomes possible to establish the voltage value required for their forced depolarization and the corresponding depolarization current.

The use of pulses with higher values of the rate of increase in voltage allows one to obtain data characterizing the process of polarization of cell membranes at the initial stage of electric exposure, which is reflected in the nature of the current fluctuations corresponding to the ascending part of the voltage. The upper value of the voltage rise rate is limited by the parameters of existing electronic switches and is of the order of 10 ¹¹ V / s.

The use of pulses with different values of the rate of rise and fall of the voltage allows you to select several different types of characteristic parameters of the test biological objects, which will be shown in example 2.

The invention is illustrated in graphic materials.

Figure 1 shows a block diagram of the proposed device for implementing the inventive method.

Figure 2 (a) shows a diagram of the measuring system of the device for a variant using a reference electrode.

Figure 2 (b) shows a diagram of a measuring system without the use of reference electrodes.

Figure 3 shows a functional diagram of the inventive device.

Figure 4 presents the appearance of the device for implementing the inventive method in a portable embodiment.

Figure 5 shows the structural diagram of the generator of test signals (option 1).

Figure 6 shows the structural diagram of the generator of test signals (option 2).

7 shows a structural diagram of a generator of test signals (option 3)

On Fig shows the characteristic dependence of current on time in the electrochemical system with the claimed type of exposure.

Figure 9 shows the dependence of current on time for example 1.

Figure 10 shows the current-voltage dependences for example 1.

11 a) shows the dependence of current on time for the first embodiment of electric action according to example 2.

11 b) shows the dependence of current on time for the second variant of the electrical effects of example 2.

On Fig shows the dependence of voltage on time for the second variant of the electrical effects of example 2.

In Fig.13 shows the dependence of current on time for the first variant of the electrical effects of example 3.

On Fig shows the dependence of current on time for the second variant of the electrical effects of example 3.

On Fig shows the dependence of current on time according to example 4.

The method is implemented using the proposed device for implementing the proposed method, a block diagram of which is shown in FIG. Block 1 is a generator of test signals, which are voltage pulses with specified parameters. Block 2 is a device - a sensor in which, for convenience, in a particular design, for example, invasive electrodes (Fig. 3) can be structurally combined and fixed, which allows you to change the interelectrode distance and the length of the invasive electrodes. A test signal through a sensor 2 with invasive electrodes is supplied to the test object 3. A measuring module 4 is connected to the sensor 2, which performs a time-coordinated measurement of electrical parameters such as current and voltage. Information about the measured signal is transmitted to the memory of computer 5, where it is stored and processed. The results are displayed on the computer display 5. The test signals are set using the computer 5.

The inventive device for implementing the method is developed on the basis of well-known measuring equipment for measuring and monitoring the electrical parameters of high current pulse processes in electrolyte solutions, described in [RU No. 2284517 "Method for determining the electrical parameters of high current pulse" Method for determining the electrical parameters of high current pulse processes in electrolyte solutions and computer measurement system].

Figure 2 (a) shows a diagram of the measuring system of the device for a variant using a reference electrode. Figure 2 (b) shows a diagram of a measuring system without the use of reference electrodes.

Using an analog-to-digital converter 6, a time-coordinated recording of the electrical parameters of the current and voltage values is carried out in an electrochemical system containing a test bioobject 3 with the subsequent transfer of this information to computer 5 for storage and processing using software that allows you to process data arrays.

As a result of the operation of the measuring system 4, time-consistent data corresponding to the voltage drop in the electrochemical system, the polarization voltage U _p at the interface of the invasive electrode - biological material, and the data of the current flowing through the test object at time moments corresponding to the recorded pulse fronts are entered into computer 5 at given test signal parameters. The measurement can take place in the mode of averaging the values of electrical parameters from 2 to 256 pulses.

The generator of test signals in the first embodiment (figure 5) consists of the following main elements:

- devices for setting the initial form of the test signal - a functional signal 11, containing a circuit for setting the form; device 11 is controlled from computer 5;

- power amplifier 12, which amplifies the original functional signal to a predetermined voltage value, ensuring the flow of the required current, thus forming a large-scale copy of it;

- 13 - power source;

- 14, 15 - connectors for connecting sensor 2 with invasive electrodes.

The generator of test signals (Fig.6) in the second embodiment consists of the following main elements:

- power source 13;

- electric energy storage unit 16; the accumulation of electrical energy can be carried out by means of capacitive, inductive elements, a transformer;

- power key 17.

The signals to the input of the power key come from the key management device 18, which in turn is controlled by a computer. The device 18 performs the function of controlled opening and locking of the key, which allows you to control the rate of rise and fall of the output voltage of the generator of test signals.

- 14.15 - connectors for connecting the sensor.

The generator of test signals in the third embodiment (Fig.7) consists of the following main elements:

- power source 13;

- electric energy storage unit 16; the accumulation of electrical energy can be carried out by means of capacitive, inductive elements, a transformer;

- power key 17, controlled by a computer.

To control the rate of rise / fall of the output voltage of the test signal generator, a variable inductance 19 - is used (inductive element pL with a variable nominal value). The rise / fall rate of the output voltage is a function of the nominal value of the inductive element 19.

- 14, 15 - connectors for connecting a sensor with invasive electrodes.

The measuring module (system) of the claimed device operates as follows: with the help of one of the inputs of the analog-to-digital converter 6, the parameters of the test signals are recorded, which makes it possible to measure the voltage U supplied to the electrochemical system with high accuracy. If necessary, use a voltage divider 7. Similarly recorded polarization voltage U _p . At the other input of the analog-to-digital converter, voltage is supplied from the current-to-voltage converter 8, which is directly proportional to the current I flowing through the test object. For a variant of the measuring system using a reference electrode, the latter is connected to one of the inputs of the analog-to-digital converter. In FIG. 2 (a), a reference electrode is connected to a second channel of an analog-to-digital converter. Using computer 5 (figure 3), the operator sets the parameters of the test signals. The test signal (voltage pulses with specified parameters) is supplied to sensor 2 (electrodes). The sensor 2 is equipped with invasive electrodes in the form of needles 9 and 9 ', the reference electrode 10 is also made in the form of a needle. This design allows you to immerse the electrodes in the tested biological objects, for example, to pierce the skin and subcutaneous fat of meat, which simplifies the test procedure. The measuring module 4 is connected to the sensor 2 immersed in the test object 3. The electrical parameters measured with the required discreteness during the electric action on the test object are transmitted from the analog-to-digital converter 6 of the measuring module 4 to the memory of computer 5 in the form of a data array. The resulting data array is stored and processed. The test results are visualized on the computer display 5.

When processing the obtained data, the current-voltage dependence and the chronoamperogram are built. The calculation of the total pulse current, capacitive and active components of the current, specific resistance and specific capacitance, and other additional parameters that serve as criteria (classification features) for further identification and determination of quality indicators can also be carried out.

Additional parameters may include:

- the values of the depolarization voltage and the corresponding depolarization current;

- the ratio of the slope of the rising / falling voltage and current;

- the time interval between the achievement of the amplitude values of the current and voltage;

- the nature of the oscillatory process for current during a period of voltage rise to a predetermined value;

- equations obtained by approximation for various sections of the dependences of current and voltage on time.

To implement an electronic measuring device in a portable version, the computer used can also be portable and placed in one housing with a test signal generator (Fig. 4).

On Fig shows a characteristic dependence of the current on time.

The total current pulse I flowing through the electrochemical system consists of two components: capacitive and active. A sharp jump in current at the beginning of the pulse is due to the capacitive component I1. Then the current value decreases to a certain value and I2 and remains constant.

The claimed method is illustrated by the following examples.

For the implementation of the electric impact, the device shown in Fig. 3 was used with the test signal generator shown in Fig. 6, which makes it possible to carry out electrical action with the following parameters: voltage per pulse - up to 500 V, pulse duration 10-700 μs, pulse repetition rate 0 , 5-4 Hz, the voltage rise / fall rate lies in the range of 10 ⁶ -10 ⁹ V / s. The Gwinstek 71062A digital oscilloscope acted as an analog-to-digital converter.

During the tests, the following conditions were fulfilled: the geometric dimensions of the invasive electrodes and the contact area of each of the electrodes with biological tissue in all measurements remained constant.

Example 1

The study subjected chicken meat (muscle tissue) with different periods of time after slaughter, namely 1, 2, 3, 4 days.

During the test period, all samples were placed in airtight plastic containers that prevent drying and were stored in an air thermostat at a temperature of 20 ° C.

To perform measurements, samples were placed on a non-conductive surface made of textolite sheet. Stainless steel needles were used as electrodes. The sizes of the needles were the same, which ensured the same density of the cathodic and anodic currents - 1: 1. The distance between the electrodes was 8 mm and remained constant during all measurements.

The electric exposure mode was as follows: the shape of the DC voltage pulses is trapezoidal, the voltage rise time to a predetermined value of 300 ns (voltage rise rate of 10 ⁹ V / s), the potential difference between the electrodes is 300 V, the pulse duration is 100 μs, and the pulse repetition rate is 1.4 Hz , the number of pulses transmitted through the electrochemical system is 16.

Electrical parameters were recorded and stored as described above (as described in the description).

The data obtained for 16 pulses were averaged directly using an analog-to-digital converter and were presented graphically in the form of ascending parts of chronoamperograms (Fig. 9) and current-voltage dependences (Fig. 10) for different periods of storage of the test object. In this case, such a display of experimental data is the most informative, which, however, does not mean the lack of informativeness of other registered parameters. Figure 9 shows that during storage from the first to the third day, the total and active current increase, and the ratio of capacitive and active components of the pulse current decreases. On the fourth day, the capacitive component of the pulsed current is practically absent, in addition, the current rise time is significantly increased. Moreover, the nature of the changes that occurred on the fourth day is quite sharp. Figure 10 shows that during storage from the first to the fourth day there is a constant decrease in the area limited by (inside) the current-voltage dependences, which also indicates a decrease in the capacitive component of the electrical resistance of biological tissue. Data on current values are given in table 1.

It is worth noting that it is on the fourth day of storage that the unsuitability of meat, from the point of view of consumer qualities, can be unambiguously determined by visual and organoleptic criteria.

A decrease in the ratio of the capacitive and active components of the pulsed current and an increase in the active current are consistent with the statement about the destruction of cell membranes during prolonged storage of meat, including under the influence of bacteria. Since it is cell membranes that largely determine the presence of the capacitive component of the impedance of biological objects. Moreover, the destruction of membranes increases the overall conductivity of such objects.

Table 1 Chicken muscle tissue electrical parameters Day of storage one 2 3 four Total current, A 0.74 0.99 1.16 0.86 Active current, A 0.46 0.76 0.99 0.85 Capacitive current, A 0.28 0.23 0.17 0.01 The share of capacitive current in the total current,% 37.8 23,2 14.7 1,2

The almost complete absence on the 4th day of storage of the capacitive component of the pulsed current unambiguously indicates a significant destruction of the tissue and, therefore, the unsuitability of this type of product for consumption. This conclusion is confirmed by studies performed by organoleptic methods.

Example 2

The study subjected samples of two fish species with the same time periods after thawing: herring and crucian carp.

During the test period, all samples were placed in airtight plastic containers that prevent drying and were stored in an air thermostat at a temperature of 20 ° C.

Electric exposure was carried out in two modes. In the first mode, trapezoidal constant voltage pulses were used, the potential difference between the electrodes was 200 V, the voltage rise time to the specified value was 211 ns (voltage rise rate 0.95 · 10 ⁹ V / s), pulse duration 100 μs, pulse repetition rate 1 , 4 Hz, the number of pulses transmitted through the electrochemical system - 16. In the second mode, DC voltage pulses of a trapezoidal shape, the potential difference between the electrodes were 400 V, the voltage rise time to the back This value was 12 μs (the voltage rise rate was 3.3 × 10 ⁷ V / s), the pulse duration was 100 μs, the pulse repetition rate was 1.4 Hz, and the number of pulses transmitted through the electrochemical system was 16.

Electric action in both modes was carried out with a ratio of the cathode area to the area of invasive anodes of 1:10. In this case, one cathode and ten anodes were used. The immersion depth of all electrodes was constant. In addition, an invasive reference electrode made of platinum was additionally used, which was placed in the test objects at a distance of 3 mm from the cathode. The voltage drop was recorded both between the counter electrodes and between the reference electrode and the cathode. Such an organization of electric action and measurement of electrical parameters makes it possible to almost completely eliminate the anodic polarization and to carry out direct measurements of the polarization of the invasive cathode – biological material interface with high reliability. The rest of the measurement procedure was as in example 1.

The data obtained were averaged directly using an analog-to-digital converter and were presented graphically in the form of ascending parts of the current versus time for the first and second modes of electric action (Fig. 11 (a, b)) and the polarization voltage of the cathode (Fig. 12) for the second mode of electrical exposure.

In Fig. 11 (a), it can be seen that for the same exposure parameters, the values of the total and active currents for herring are much higher than for crucian carp, and the share of the capacitive current in the total current for crucian carp is 30.4% for herring - 21.6%. The nature of the oscillatory process with increasing current for the samples studied is also different.

In Fig. 11 (b), it is seen that when using the second embodiment of electric action, with a lower rate of voltage rise, it is possible to isolate additional characteristic parameters of the test objects, namely, the magnitude of the depolarization current and the depolarization voltage. However, the determination of the nature of the oscillatory process for the current in this case becomes almost impossible (significantly complicated). Therefore, for a number of cases it is advisable to use an electric effect containing pulses with various parameters in the claimed range of parameters.

On Fig shows that for both samples studied, the phenomenon of depolarization of the cathode – biological material interface is observed. In this case, the depolarization voltage for each of the studied samples is different.

The measurement results of the parameters of the pulse voltage and current are presented in tables 2 and 3.

table 2 Electrical parameters of fish samples in the first embodiment of electric exposure Sample Name Crucian Herring Total current, A 0.46 0.88 Active current, A 0.32 0.69 Capacitive current, A 0.14 0.19 The share of capacitive current in the total current,% 30,4 21.6

Table 3 Electrical parameters of fish samples in the second variant of electric exposure Sample Name Crucian Herring Total current, A 1.44 3.42 Active current, A 1.33 2.91 Capacitive current, A 0.11 0.51 Depolarization current, A 0.27 0.85 Depolarization voltage, V 144.9 106.8 The share of capacitive current in the total current,% 7.6 14.9

Herring samples, in comparison with crucian samples, have a higher total conductivity with a lower ability to polarize, which is due to the difference in the resistance values inside and intercellular media and the difference in the capacitive properties of the membranes of these test objects.

Thus, it is shown that the inventive method allows the determination of species of fish.

Example 3

The study was subjected to pig meat (muscle tissue) with different periods of time after slaughter, namely 1, 2, 3, 4 days.

Sample preparation, storage of samples and measurement procedure were as in example 1.

The electric exposure mode was as follows: the shape of the DC voltage pulses is trapezoidal, the voltage rise time to a predetermined value of 200 ns (voltage rise rate 10 ⁹ V / s), the potential difference between the electrodes is 200 V, the pulse duration is 150 μs, the pulse repetition rate is 1.4 Hz , the number of pulses transmitted through the electrochemical system is 16.

The obtained data were presented graphically in the form of ascending parts of chronoamperograms (Fig. 13) and current-voltage dependences (Fig. 14) for different periods of storage of the test object.

On Fig shows that during storage from the first to the third day the total and active current increase, and the ratio of capacitive and active components of the pulse current decreases. On the fourth day, the capacitive component of the pulsed current is practically absent, in addition, the current rise time is significantly increased. Moreover, the nature of the changes that occurred on the fourth day is quite sharp. On Fig shows that during storage from the first to the fourth day there is a constant decrease in the area limited by (within) the current-voltage dependencies, which also indicates a decrease in the capacitive component of the electrical resistance of biological tissue. On the fourth day of storage, the unsuitability of meat, from the point of view of consumer qualities, can be unambiguously determined by visual and organoleptic criteria. Data on current values are given in table 1.

Table 4 Chicken muscle tissue electrical parameters Day of storage one 2 3 four Total current, A 1.05 1,07 1.09 0.74 Active current, A 0.72 0.80 0.83 0.70 Capacitive current, A 0.33 0.27 0.26 0.04 The share of capacitive current in the total current,% 31,4 25,2 23.9 5,4

The almost complete absence on the 4th day of storage of the capacitive component of the pulsed current unambiguously indicates a significant destruction of the tissue and, therefore, the unsuitability of this type of product for consumption. This conclusion is confirmed by studies performed by organoleptic methods.

Example 4

Electric exposure was carried out as in the above examples using invasive electrodes. An exact chip resistor of the SMD 1206 series with a nominal value of 100 Ohms and an accuracy of ± 1% (F) acted as an object of electrical influence. The mode of electrical action on the resistor and the method of recording electrical parameters was as in example 1.

The data obtained for 16 pulses were averaged directly using an analog-to-digital converter and were presented graphically in the form of the ascending part of the chronoamperogram (Fig. 15) at voltages of 200 V and 400 V.

From the dependence shown in FIG. 15, it is seen that the capacitive component of the pulse current is absent, and there is also no oscillatory process for the current during the rise period to the specified value. Thus, it is shown that the complex nature of the dependence of current on time with the proposed method of analytical control is not a result of distortion of the measurement results due to noise (contribution) created (introduced) by the power source (measuring devices), the "bounce" of elements of electrical circuits, wires, electrical contacts , electrodes, etc., but is the response of the measuring system, which corresponds to the properties of the test object.

The results of measurements of the electrical parameters of electrochemical processes in the test objects, which are biological tissue materials, obtained in the above examples show that the recorded responses are characteristics of the biological tissue, and not the measurement errors caused by certain factors. It is proved that the shape and dynamics of changes in volt-ampere and chrono-amperometric dependencies is in strict accordance with the type of biological tissue and its properties.

From the presented dependencies it is seen that when implementing the claimed method in the electric action on test objects, recording the electrical parameters of the system and subsequent mathematical processing of the data obtained, it is possible to identify and determine the quality indicators of biological tissues, for example, animal meat.

Thus, it has been shown that irreversible changes occurring during the storage of biological tissue samples are in strict correlation with the electrical parameters of electrochemical processes excited by the method described above (by applying short voltage pulses with high potential differences to test objects).

Claims (25)

1. A method for determining the electrical characteristics and / or identification of biological objects, including installing electrodes on a biological object, applying voltage to them, measuring current and voltage values, storing and processing an array of obtained data, characterized in that the current and voltage values are measured simultaneously electrical action on a biological object, while electrical action is carried out by at least one voltage pulse with an adjustable value of the slew rate and / or cn voltage levels of at least 10 ⁴ V / s. 2. The method according to claim 1, characterized in that they use voltage pulses, the rise / fall rate of which lies in the range from 10 ⁷ to 10 ⁹ V / s. 3. The method according to claim 1 or 2, characterized in that use voltage pulses of a trapezoidal shape with a duration of 5-300 μs. 4. The method according to claim 1 or 2, characterized in that the use of voltage pulses of a triangular shape with a duration of 5-300 μs. 5. The method according to claim 1, characterized in that use voltage pulses up to 1000 V, preferably 90-300 V. 6. The method according to claim 1, characterized in that when they are electrically exposed to a biological object by a group of pulses, they are transmitted at a frequency lying in the range of 0.5-10 Hz, preferably 0.8-2.0 Hz. 7. The method according to claim 6, characterized in that use pulses with different parameters, for example, with different values of the slew rate and the rate of voltage drop. 8. The method according to claim 1, characterized in that at least two current-carrying electrodes are used to supply voltage pulses to the biological object and measure the electrical characteristics: the anode and cathode, which are placed on the biological object or immersed in a biological object. 9. The method according to claim 1, characterized in that for measuring electrical characteristics, at least one reference electrode is additionally used, which is placed on a biological object or immersed in a biological object. 10. The method according to claim 1, characterized in that the electrical effect on the biological object is carried out by anodic-cathodic current with a ratio of cathodic and anodic current density in the range from 1: 1 to 10: 1. 11. The method according to claim 1, characterized in that preferably the electrical effect is carried out at a temperature of the biological object and / or electrodes equal to 20 ° C. 12. The method according to claim 1, characterized in that as an array of data of electrical characteristics using an array of data, time-coordinated values of current and voltage. 13. The method according to claim 1, characterized in that for the identification of biological objects and / or their state, the processing of the resulting array is carried out by comparing the resulting array of electrical characteristics data with arrays previously obtained for a known biological object, and based on the comparison, they conclude form or condition of a biological object. 14. The method according to claim 1, characterized in that if the test object is food or raw materials for their manufacture, then, to determine the quality indicators, the test object is exposed to electric current, current and voltage drops are measured, and the array is stored obtained data and comparing the obtained data with arrays obtained for the test objects with known quality indicators, based on the comparison, they conclude about the quality of food products. 15. A device for determining the electrical characteristics of biological objects, containing a generator of test signals, configured to control the rate of rise and / or fall of the output voltage pulses, electrodes for supplying voltage pulses to the biological object and simultaneously measure the electrical characteristics of the object, a measuring module, wherein electrodes are connected to the measuring module, a computer for controlling the generator of test signals, storage and processing of masses Islands electrical characteristics of the data. 16. The device according to p. 15, characterized in that it contains at least one additional electrode - a reference electrode connected to a measuring module for measuring polarization voltage. 17. The device according to p. 15 or 16, characterized in that the electrodes for supplying voltage to the biological object and the reference electrode are made in the form of invasive needles for immersing the electrodes in the studied biological object. 18. The device according to 17, characterized in that the electrodes for supplying voltage to the biological object and the reference electrode are structurally combined into a single unit - the sensor and installed in it with the possibility of changing their length and interelectrode distance. 19. The device according to 17, characterized in that to increase the cathode current density using many invasive electrodes in the form of needles with the same size, while the needles are connected in parallel and perform the function of a cathode. 20. The device according to p. 15, characterized in that the measuring module is configured to coordinate the measurement of current and voltage in time. 21. The device according to clause 15, wherein the measuring module is a two-channel, in which the first channel contains a voltage divider connected to an analog-to-digital converter for measuring voltage, the second channel contains a current-voltage converter, also connected to an analog-to-digital converter to measure current. 22. The device according to clause 15, wherein the measuring module is made three-channel, in which the first channel contains a first voltage divider connected to an analog-to-digital converter for measuring voltage, the second channel contains a second voltage divider connected to an analog-to-digital converter for polarization voltage measurement and the third channel contains a current-voltage Converter, also connected to an analog-to-digital Converter for measuring current. 23. The device according to p. 15, characterized in that the test signal generator consists of the following main elements: a device for setting the initial form of the test signal controlled from a computer, a power amplifier that amplifies the initial test signal to a predetermined voltage value, ensuring the flow of the required current , thus forming its large-scale copy, and a power source. 24. The device according to clause 15, wherein the test signal generator consists of the following main elements: power source; electric energy storage unit, a power key controlled by a control device that performs the function of opening and locking the key, which allows you to control the rate of rise and fall of the output voltage of the generator of test signals. 25. The device according to clause 15, wherein the test signal generator consists of the following main elements: power source; an electric energy storage unit, a power switch controlled by a computer, and a variable inductance was used to control the rate of rise and / or fall of the output voltage of the test signal generator.

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