SU1397024A1 - Method and apparatus for determining components of impedance of biological object - Google Patents

Abstract

The invention consists in determining the active and reactive components, the impedance of the voltage measured on a bioobject. In order to improve the accuracy of measurements, they are conducted at the moments when the mains voltage passes through a zero value and, after the second measurement, a current pulse of opposite polarity equal in duration to the first pulse is applied to the bioobject. A device for implementing the method comprises a pulse generator 1, delay elements 2, 33, triggers 3, 10, 15, 26, 31, Display units 4, 23, control current source 5, electrodes, zero-level fixing unit 6, And 7 elements, 11, 14, 16, .27, a counter with a decoder 8, shapers 9, 13, 18, 20, 24, 25, 28 pulses, reversible counter 12, registers 17, 22, elements of RISh 19, 29, analog-to-digital converter 21 , initial reset unit 30, switch 32, code setter 34, sample-storage element 35. 2 sec. f-ly, 3 ill. i cl

Description

with

CD

ABOUT

four

 asufoi j

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The invention relates to medical technology, in particular to methods and devices for studying the impedance properties of biological objects.

The purpose of the invention is to increase accuracy.

Fig. 1 shows a structural electrical circuit of the device; in fig. 2 and 3 are signal plots explaining the operation of the device.

The method of determining the impedance components of a biological object consists in applying a constant current pulse to a biological object, measuring the voltage on a biological object at two fixed times after the current pulse begins, and determining the active and reactive components of the biological object impedance using the measured voltage values , moreover, voltage measurements on a bioobject are carried out at the moments when the mains voltage passes through zero, and after the second measurement, a current pulse of the opposite p is applied to the bioobject l polarity equal in duration to the first pulse.

A device for determining the components of the impedance of a biological object contains (Fig. 1) a pulse generator 1, a first delay element 2,. The first trigger 3, the first display unit 4 and the controlled source 5 of the current, the output of which is connected to the electrode bus, are connected in series to the zero-level fixing unit 6, the input of which is connected to the mains voltage bus, the first element 7, the counter with the decoder, the first pulse shaper 9, the second trigger 10, the second element 11, the second input of which is connected to the output of the pulse generator 1, a reversible counter 12, the second pulse generator 13 pulses the third element 14, the third trigger 15, the fourth element 16 and the first register 17 you the stroke of which is connected to the input of the first display unit 4 and to the first output bus of the device, the third pulse generator 18, the first element OR 1-9, the fourth pulse driver 20, the analog-to-digital converter (AID)

21, the second register 22 and the second display unit 23, whose input is connected to a second output bus device, are connected in series to a fifth pulse shaper 24, a sixth pulse shaper 25, a fourth trigger 26, and a fifth And element 27 whose output is connected to the second input of the second register 22, and the second input - to the second input of the fourth element And 16 to the second you-; - to the ADC 21, the first output of which is connected to the second input of the first register 17, the seventh pulse generator 28 and the second element OR 29, serially connected, the second input of which is connected to the input of the sixth pulse generator 25 and to the second input of the first element OR 19, and the output - to the second input of the reversible counter 12, the third input of which is connected to the second input of the third element 14 and to the input of the first shaper 9 pulses, sequentially connected initial reset unit 30, the input of which is connected to the power bus,. and fifth trigger 315, the code of which is connected to the second

5 0 5

30 seconds

Sh

five

five

the input of the first element I 7, the second input with the first inputs of the first element I 7 and the first trigger 3, the third input with the output of the first trigger 3 and with the input of the seventh imager 28 pulses, and the quarter input with the second inputs of the first trigger 3 and a counter with a decoder 8, the second output of which is connected to the input of the third pulse generator 18, the third output — to the input of the fifth pulse former 24, and the fourth output - to the input of the first delay element 2, the output of which is connected to the second input of the second trigger 10, the third entrance is n Connected to the first input of the third trigger 15, switch 32, the first input of which is connected to the code of the third trigger 15, the second input to the output of the fourth trigger 26, the third input to the first reference voltage bus, the fourth input to the second reference voltage bus, and the output is to the input of the controlled current source 5, the second element. 33 delays, the input and output of which are connected respectively to the fifth output and the second input of the counter with the decoder 8, the third input of the computer is connected to the first input of the fifth trigger 31, to the third input of the first trigger 3 and to the second input of the ADC 21s unit 34 of the code , connected

to the fourth input of the reversible counter 12, the second output of which is connected to the fourth input of the second trigger 10 and to the second input to the fourth. the trigger 26, the first input of which is connected to the second input of the third trigger 15, and the sample and storage element 35, the first input of which is connected to the input of the fourth form Q heat pulse 20, the second input to the output of the controlled current source 5, and to the third input of the ADC 2I.

The method is carried out as follows. J5

A bioobject is fed through electrodes by a pulse of stabilized current of a certain polarity (for example, positive) and amplitude I. The transient process of increasing the voltage on the bioobject occurs at the fixed two time points due to the capacitive nature of the reactive component of the impedance of the bioobject. t, and t. after the start of the current pulse, obtaining, respectively, the values of the voltage U and U. The measurement at time t is performed when the capacity of the biological object tissues is fully charged and the transient process is completed.

In order to eliminate the influence of network interference, the measurement of the voltage on a bioobject is carried out at the moments when the network voltage passes through the zero level (pt negative value to positive). For this, a current pulse is applied to the bioobject during the time interval t until the transition the network voltage is zero, equal, for example, 1 ms, and the value is set equal to the period of the network voltage, for example, 20 ms (at a network frequency of 50 Hz). The magnitude of the stabilized current 1 is chosen such that during the time of action of the current pulse a full charge of the capacity of the tissue of the bio-object occurs. Then the voltage on the bioobject is proportional to the magnitude of the active component of the impedance of the bioobject.

The active resistance R of a bioobject is determined by the formula (with a parallel bioobject replacement scheme)

thirty

35

40

45

50

and R-

- 17. . .

voltage on a bioobject at time t / j.

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The equivalent capacitance C of the tissues of the bio-object is calculated using

 f - - l) t

 about; .

where C is the voltage on the bioobject at the moment of time t ,.

In this case, it is assumed that the time is counted from the leading edge of the current pulse 1.

After the second measurement, eg. neither at the time t, the back front of the current pulse is formed, and a second current pulse of the opposite (for example, negative) polarity equal to the first pulse is applied to the bioobject, which eliminates the influence of the polarization of the biological object tissues and C in the next measurement cycle.

The device works as follows.

When the power supply voltage + E of the device is turned on, the initial reset unit 30 generates a pulse (FIG. 2a) that resets the first trigger 3 (the start trigger)) (FIG. 2d), the fifth trigger 31 (synchronization trigger with the network voltage) , a counter with a decipheror 8 (fig. 2e) and an ADC 21. The zero-level fixing unit 6 generates pulses (figo 2c) at the moments of transition by a network voltage of zero level (from negative values) coming at its input to the network voltage (fig. 2b) positive values of network voltage). The first pulse from the output of the zero-fixing unit 6 puts the first trigger 3 (fkg. 2m and fifth trigger 31) into a single state, which ensures the passage of pulses through the first element 7 to the first (clock) counter input with the decoder 8 (Fig. 2e ).

The signal from the output of the first trigger 3, the seventh pulse shaper 28 generates a pulse (Fig. 2h), which passes the second element OR 29 and allows entering the tracking code from the code setter 34 to the reversible counter 12 via its second input (Fig. 2o) .

The incrementing code sets the time interval t from the beginning of the first stabilized current pulse (for example,

positive polarity) supplied to the bioobject, until the first measurement of the voltage U, on the bioobject. If the device sets the time intervals in the device with an accuracy of one microsecond (frequency of the generator 1 pulses is 1 MHz), code 1000 is entered into the reversible counter 12. The signal from the first output of the counter with the decoder 8 (Fig. 2g) sets the reversible counter 12 through its third entry in add mode. The output impulse of the first impregnator 9 pulses (Fig. 2i) transfers the second flip-flop 10 (increase trigger) to this state Ofig. 2p), in which the passage of clock pulses from the output of generator 1 of pulses through the second element I 11 to the first (clock) input of the reversible counter 12 is allowed,

The reversible counter 12 counts in addition mode by adding to it an addition code to a code equivalent to the period of the network voltage. With a network frequency of 50 Hz and a clock frequency of 1 MHz, the reversible counter 12 counts to a value of Q 20000, i.e. in this case, 19000 pulses are counted, which corresponds to a time interval of 19 ms from the time of the transition by a network voltage of zero level. Since the output signal of the reversible counter 12 through the second pulse shaper 13, the third element is AND 14, the third trigger 15 (the trigger of the first current pulse) (FIG, 2T) and the switch 32 triggers the controlled source 5.tOKH and the supply of a stabilized current pulse the bioobject (fig. 2f), the first measurement of the voltage and the bioobject is provided through the time interval in ms at the moment of the desired transition to zero by the mains voltage.

The output signal of the reversible counter 12 also resets the second trigger 10, which stops the flow of clock pulses to the reversing counter 12..

According to the signal from the second output of the counter with the decoder 8, the third pulse shaper 18 generates a pulse (Fig. 2k), which through the first element I.TII 19 records

5 About Q with

five

{fig. 2x) at the time t of the analog value of the voltage U on the bioobject to the element 35 for sampling and storage. A pulse from the output of the fourth pulse driver 20 (Fig. 2c) triggers the A / D converter 21, which converts the value of U into a digital form. The end of measurement signal from the second output of the A / D converter 21 (Fig. 2h), through the fourth element And 16, enters the code into the first register 17 and into the first display unit 4 (Fig. 2b). The U code also goes to the first output bus of the device.

The signal from the output of the fifth pulse driver 24 through the first element OR 19 records at the time t an analog voltage U on the bioobject, which is proportional to the active component of its impedance, to the sample and storage element 35, and on the second pulse from the output of the fourth driver 20 pulses, the ADC 2 is started, followed by the voltage code being fed to the second register 22 (FIG. 2), to the second display unit 23 and to the second output bus of the device codes U., and from the first and second output buses of the device goes to the external a computing unit for calculating the active and capacitive banks of the impedance of a bioobject using the above formulas.

The time diagram of the operation of the device (Fig. 3) is given at time t, j of the second voltage recording on the bioobject in element 35. selecting and storing and forming the second stabilized current pulse through the bioobject (of opposite polarity, for example, negative). On the falling edge of the output pulse of the second pulse former 24 (FIG, Sv), the sixth pulse former 25 produces a short pulse (FIG. 3d), resetting the third trigger 15 (FIG, 3B) and setting the 1st fourth trigger 26 (trigger of the second current pulse opposite polarity) to the unit state (fig. 2u, rear). The output signal of the fourth trigger 26 through the switch 32 and the controlled current source 5 provides the bioobject of the second pulse of the current opposite to polarity (fig. 2f). The fourth driver 20 pulses provides

the delay of the trigger signal of the A / D converter 21 (Fig. 3i) with respect to the recording signal in the sample and storage element 35 (Fig. 3).

Equality of the durations of the second (for example, negative) current pulse through the bioobject and the first (for example, positive) current pulse through the bioobject is provided at the second stage of operation of the reversing counter 12 and the second trigger 10. Dp this signal from the output of the fifth pulse former 24 through the second element OR 29 is also fed to the second input of the reversible counter 12 (Fig. 2o) and enables the completion of the additional calculation code from the unit 34 of the code. After passing a negative current pulse through a bioobject for one period of mains voltage (Fig. 2f), the signal from the fourth output of the counter with the decoder 8 through the first delay element 2 (Fig. 2m sets the second trigger 10 to one) (Fig. 2n). ), which allows the passage of clock pulses from the pulse generator 1 to the first input of the reversible counter 13, which works on subtraction to zero during the time interval t,. At ms and the clock frequency MHz, the reversible counter 12 counts 1000 pulses (Imputation code) from 1000 to zero, whereupon overflow pulse P output from the second down counter 12 resets the second flip-flop 10 and a forth flip-flop 26, thereby forming a rear

front of negative current pulse

through a bioobject (Fig. 2f), the duration of which is equal to the duration of the first (positive) current pulse through the bioobject. The first delay element 2 also ensures that the duration of the positive and negative current pulses through the bioobject is variable, since it is created: the delay is equal to twice the operating time of the first driver, 24 pulses (Fig. Sv, f).

The signal from the fifth output of the counter with the decoder 8 through the second delay element 33 (Fig. 2n) resets the first trigger 3, the fifth trigger 31 and the counter with the decoder 8, the delay Element 33 provides the separation in single state

r 20 5 o

five

0

five

0

The first trigger 3 and the supply (HI-inputs to the inputs from the fifth trigger 31 and the counter with the decoder 8. The pulse from the output of the zero-fixing unit 6, the first trigger 3 is set to one and the new component is detected impedance bioobject.

Thus, the device makes it possible to determine the values of the impedance components of biological tissues in a pulsed mode with increased accuracy due to the elimination of the influence of network interference and tissue polarization on the process of measuring the parameters of a bio-object.

Claims (2)

1. A method for determining the impedance components of a biological object consisting in applying a stabilized current pulse to a biological object, measuring the voltage on a biological object at two fixed points in time after the start of a current pulse, and determining the active object impedance components of the biological object by measuring the voltage values due to the fact that, in order to increase the accuracy of measurement, the voltage on a bioobject is carried out at the moments when the network voltage passes through a zero value, and after the second measurement t on bioobject current pulse of opposite polarity equal in duration to the first pulse. 2. A device for determining the impedance components of a biological object, comprising a pulse generator, the first delay element, the first trigger, the first indication block and the control current source, the output of which is connected to the electrode bus, characterized in that It contains serially connected zero-level fixing unit, the input of which is connected to the mains voltage bus, the first element I, the counter with the decoder, the first pulse shaper, the second trigger, the second element I, and the second d which is connected to the output of the pulse generator, a reversible counter, the second driver and mylcov, tre 9 13 And the third element, the third trigger, the fourth element And and the first register, the output of which is connected to the input of the first display unit and to the first output bus of the device, are in series connected the third pulse generator, the first OR element, the fourth pulse shaper, the analog-digital converter, the second the register and the second display unit, whose input is connected to the second output bus of the device, the fifth pulse shaper, the sixth pulse shaper, the fourth trigger and the fifth element are connected in series And, the output of which is connected to the BtopoMy input of the second register, and the second input - to the second input of the fourth element And and to the second output of the analog-digital converter, the first output of which is connected to the second input of the first register, serially connected the seventh pulse shaper second element OR, The second input of which is connected to the input of the sixth pulse former and R to the second input of the first ISh- element, and the output to the second input of the reversible counter, the third input of which is connected to the second input of the third And element and with the input of the first pulse generator, serially connected initial reset unit, the input of which is connected to the power bus, and a five trigger, the output of which is connected to the second input of the first element And, the second input - with the first inputs of the first, element And and the first trigger, the third input - with the output of the first trigger and with the input of the seventh form 0 five 7024 - „. five thirty 35  ten pulse bodies, and the fourth input - with the second inputs of the first trigger and counter with the decoder, the second output of which is connected to the input of the third pulse generator, the third output - to the input of the fifth pulse former, and the fourth output - to the input of the first delay element, whose output is connected with the second input of the second trigger, the third input of which is connected to the first input of the third trigger, the switch, the first input of which is connected to the output of the third trigger, the second input to the output of the fourth trigger, the third input to the first bus not the reference voltage, the fourth input to the second voltage reference bus, and the output to the input of the controlled current source, the second delay element, the input and output of which are connected respectively to the fifth output and the second input of the counter to the decoder, the third input of which is connected to the first input of the fifth trigger, to the third input of the first trigger and to the second input of the analog-digital converter, code setter, connected to the fourth input of the reversible counter, the second output of which is connected to the fourth input of the second trigger the second input of the fourth flip-flop, the first input of which is connected to the second input of the third flip-flop, and a sample and storage element, the first input of which is connected to the input of the fourth pulse generator, the second input to the output of the controlled current source and the output to the third input of the analog-digital converter Well and l m n o p R with t and f X and u Uf u tj iz FIG. 2 but 50G network (4 and ъ g Fig.Z