阅读说明：本技术 压阻式压力感测电路 (Piezoresistive pressure sensing circuit ) 是由 王武涛 熊双涛 于 2019-09-03 设计创作，主要内容包括：本公开描述一种压阻式压力感测电路,其应用于血管内压力测量导管中,其包括：感测单元,其用于检测血管内的血压并输出血压信号,感测单元包括具有第一可变电阻元件的第一压力感测部件和具有第二可变电阻元件的第二压力感测部件；处理单元,其与感测单元连接并接收由感测单元测量的测量血压信号,并且对测量血压信号进行处理；以及计算单元,其接收由处理单元处理后的测量血压信号、以及来自存储单元的补偿参数和函数关系,并且基于测量血压信号、补偿参数和函数关系计算出真实血压值。在这种情况下,能够使计算单元在计算时基于上述补偿系数和函数关系得出正确的血压值,能够进一步提高血管内血压值测量的准确性。(The present disclosure describes a piezoresistive pressure sensing circuit for application in an intravascular pressure measurement catheter, comprising: a sensing unit for detecting blood pressure in a blood vessel and outputting a blood pressure signal, the sensing unit including a first pressure sensing part having a first variable resistance element and a second pressure sensing part having a second variable resistance element; a processing unit connected to the sensing unit and receiving the measured blood pressure signal measured by the sensing unit and processing the measured blood pressure signal; and a calculation unit which receives the measured blood pressure signal processed by the processing unit, and the compensation parameter and the functional relationship from the storage unit, and calculates a true blood pressure value based on the measured blood pressure signal, the compensation parameter and the functional relationship. In this case, the calculation unit can obtain an accurate blood pressure value based on the compensation coefficient and the functional relationship at the time of calculation, and the accuracy of measurement of the intravascular blood pressure value can be further improved.)

1. A piezoresistive pressure sensing circuit for use in an intravascular pressure measurement catheter,

the method comprises the following steps:

a sensing unit for detecting blood pressure in a blood vessel and outputting a blood pressure signal, the sensing unit including a first pressure sensing part having a first variable resistance element and a second pressure sensing part having a second variable resistance element, resistance values of the first and second variable resistance elements being changed by changes in pressure and temperature;

a processing unit connected with the sensing unit and receiving a measured blood pressure signal measured by the sensing unit and processing the measured blood pressure signal;

a storage unit storing at least a compensation coefficient including a temperature for the sensing unit, a pressure for the sensing unit, and a sensitivity for the sensing unit, and a first functional relationship of a measured value of the first variable resistance element to a real value, and a second functional relationship of a measured value of the second variable resistance element to a real value; and

a calculation unit that receives the measured blood pressure signal processed by the processing unit, and the compensation parameter and the functional relationship from the storage unit, and calculates a true blood pressure value based on the measured blood pressure signal, the compensation parameter, and the functional relationship.

2. The piezoresistive pressure sensing circuit according to claim 1,

the sensing unit further comprises a third resistance element and a fourth resistance element, one end of the first variable resistance element is connected with one end of the second variable resistance element and is connected with a power supply in parallel, and the other end of the first variable resistance element is connected with one end of the third resistance element;

the other end of the second variable resistive element is connected to one end of the fourth resistive element, and the other end of the third resistive element is connected to the other end of the fourth resistive element and grounded.

3. The piezoresistive pressure sensing circuit according to claim 2,

the processing unit comprises a first amplifier, a second amplifier and an analog-to-digital converter, wherein the input end of the first amplifier, the other end of the second variable resistance element and one section of the fourth resistance element are connected, the analog-to-digital converter is provided with a first connecting end, a second connecting end and an output end, the first connecting end and the second connecting end serve as input ends, and the output end of the first amplifier is connected with the first connecting end of the analog-to-digital converter;

the input end of the second amplifier is connected with the other end of the first variable resistance element and one end of the third resistance element, and the output end of the second amplifier is connected with the second connecting end of the analog-to-digital converter;

the output end of the analog-to-digital converter is the output end of the processing unit.

4. The piezoresistive pressure sensing circuit according to claim 1,

the storage unit is arranged in the sensing unit.

5. The piezoresistive pressure sensing circuit according to claim 3,

the amplifier further comprises a fifth resistance element, a sixth resistance element, a first capacitor and a second capacitor, wherein one end of the fifth resistance element is connected with the other end of the second variable resistor and one end of the fourth resistance element, and the other end of the fifth resistance element is connected with one end of the first capacitor and the input end of the first amplifier;

the other end of the first capacitor is grounded;

one end of the sixth resistance element is connected to the other end of the first variable resistance element and one end of the third resistance element, and the other end of the sixth resistance element is interconnected to one end of the second capacitor and the input end of the second amplifier;

the other end of the second capacitor is grounded.

6. The piezoresistive pressure sensing circuit according to claim 1,

the first functional relationship and the second functional relationship are linear relationships respectively.

7. A method for compensating pressure of a piezoresistive pressure sensing circuit,

the method comprises the following steps:

replacing a first variable resistance element and a second variable resistance element by a plurality of resistors with known resistance values, and calculating parameters of a first functional relation and a second functional relation according to the first functional relation between the measured value of the first variable resistance value and a real value and the second functional relation between the measured value of the second variable resistance value and the real value;

measuring resistance values of the first variable resistance element and the second variable resistance element under a plurality of different temperatures and pressures, and finding actual values of the first variable resistance element and the second variable resistance element based on the first functional relationship, the second functional relationship, and the parameter; and is

Under a plurality of different temperatures and pressures, calculating a third functional relation of the pressure and the temperature of the first variable resistor according to the real value of the first variable resistor element, and calculating a fourth functional relation of the pressure and the temperature of the second variable resistor according to the real value of the second variable resistor element, thereby calculating a temperature-to-resistance influence coefficient, a pressure-to-resistance influence coefficient and a temperature-to-sensitivity influence coefficient of the first variable resistor element and the second variable resistor element;

and calculating a real blood pressure value based on the parameter, the temperature-to-resistance influence coefficient, the pressure-to-resistance influence coefficient, the temperature-to-sensitivity influence coefficient, the third functional relationship and the fourth functional relationship.

8. The compensation method of claim 7,

the third functional relationship and the fourth functional relationship are respectively:

R＝R₀+(1+k_T)^T+k_PP(1+k_S)^T

wherein R is a true value of the first variable resistance element or the second variable resistance element, R₀Is an initial resistance value, k_TAs the temperature-dependent resistance coefficient, k_PFor the influence of pressure on the resistivity, k_ST is temperature, and P is pressure.

9. The compensation method of claim 7,

the first functional relationship and the second functional relationship are linear relationships respectively.

Technical Field

The present disclosure generally relates to a piezoresistive pressure sensing circuit.

Background

Due to the limitation of the sensor processing technology, the pressure measurement result of some half wheatstone bridge piezoresistive pressure sensors is greatly influenced by temperature, and the pressure measurement result needs to be compensated by using the temperature of the sensor. In some cases, the temperature of the sensor can be measured by a special temperature measuring component, but the method has a great influence on the structure and the volume of the sensor, and the other way is to calculate the temperature of the sensor through the change condition of variable resistors of two half bridges of the sensor.

The method mainly comprises the following steps that firstly, the temperature is calculated by directly using a half-bridge resistor output by the ADC, and the calculated temperature is inaccurate due to the fact that the resistor output by the ADC is not equal to the real resistance value of a sensor half bridge under the condition that a filter or other circuits exist in the circuit; the second is that the calculation process is too dependent on the correlation coefficient (such as the influence coefficient K of the temperature on the resistance) given by the sensor manufacturer_TPressure on resistance coefficient of influence K_PTemperature-sensitivity influence coefficient K_S) The dispersion of the coefficients is large, so that the temperature difference calculated by different sensors is large, the consistency of temperature measurement is poor, and the measured pressure value is inaccurate.

Disclosure of Invention

In view of the above conventional circumstances, an object of the present disclosure is to provide a piezoresistive pressure sensor structure and method capable of accurately measuring a pressure value.

To this end, the present disclosure provides, in a first aspect, a piezoresistive pressure sensing circuit for use in an intravascular pressure measurement catheter, comprising: a sensing unit for detecting blood pressure in a blood vessel and outputting a blood pressure signal, the sensing unit including a first pressure sensing part having a first variable resistance element and a second pressure sensing part having a second variable resistance element, resistance values of the first and second variable resistance elements being changed by changes in pressure and temperature; a processing unit connected with the sensing unit and receiving a measured blood pressure signal measured by the sensing unit and processing the measured blood pressure signal; a storage unit storing at least a compensation coefficient including a temperature for the sensing unit, a pressure for the sensing unit, and a sensitivity for the sensing unit, and a first functional relationship of a measured value of the first variable resistance element to a real value, and a second functional relationship of a measured value of the second variable resistance element to a real value; and a calculation unit that receives the measured blood pressure signal processed by the processing unit, and the compensation parameter and the functional relationship from the storage unit, and calculates a true blood pressure value based on the measured blood pressure signal, the compensation parameter, and the functional relationship.

In the first aspect of the disclosure, the storage unit stores the compensation coefficient including the temperature compensation coefficient, the pressure compensation coefficient and the sensitivity compensation coefficient, and the first functional relationship between the measured value of the first variable resistance element and the actual value, and the second functional relationship between the measured value of the second variable resistance element and the actual value, so that the calculation unit can obtain the correct blood pressure value based on the compensation coefficient and the functional relationship during calculation, and the accuracy of the intravascular blood pressure value measurement can be further improved.

In addition, in the piezoresistive pressure sensing circuit according to the first aspect of the disclosure, optionally, the sensing unit further includes a third resistive element and a fourth resistive element, one end of the first variable resistive element and one end of the second variable resistive element are connected and connected to a power supply, and the other end of the first variable resistive element and one end of the third resistive element are connected; the other end of the second variable resistive element is connected to one end of the fourth resistive element, and the other end of the third resistive element is connected to the other end of the fourth resistive element and grounded. Therefore, the piezoresistive pressure sensing circuit can simultaneously solve pressure values and temperature values in the calculating unit according to the pressure signals measured by the two paths of variable resistance elements and the temperature signals applied by the outside.

In addition, in the piezoresistive pressure sensing circuit according to the first aspect of the disclosure, optionally, the processing unit includes a first amplifier, a second amplifier, and an analog-to-digital converter, an input end of the first amplifier, another end of the second variable resistive element, and a section of the fourth resistive element are connected, the analog-to-digital converter has a first connection end and a second connection end as input ends, and an output end, and the output end of the first amplifier is connected to the first connection end of the analog-to-digital converter; the input end of the second amplifier is connected with the other end of the first variable resistance element and one end of the third resistance element, and the output end of the second amplifier is connected with the second connecting end of the analog-to-digital converter; the output end of the analog-to-digital converter is the output end of the processing unit. Therefore, the weak signal output by the sensing unit can be amplified by the amplifier, and the analog signal output by the sensing unit can be converted into a digital signal which can be identified by the calculating unit by the analog-to-digital converter.

In the piezoresistive pressure sensing circuit according to the first aspect of the disclosure, the storage unit may be disposed in the sensing unit. Thereby, the compensation coefficient and the first variable resistive element and the second variable resistive element can be in one-to-one correspondence.

In addition, the piezoresistive pressure sensing circuit according to the first aspect of the present disclosure may further include a fifth resistive element, a sixth resistive element, a first capacitor, and a second capacitor, wherein one end of the fifth resistive element is connected to the other end of the second variable resistor and one end of the fourth resistive element, and the other end of the fifth resistive element is connected to one end of the first capacitor and the input terminal of the first amplifier; the other end of the first capacitor is grounded; one end of the sixth resistance element is connected to the other end of the first variable resistance element and one end of the third resistance element, and the other end of the sixth resistance element is interconnected to one end of the second capacitor and the input end of the second amplifier; the other end of the second capacitor is grounded. Therefore, the current limiting function of the fifth resistor element and the sixth resistor element can be utilized to protect the circuit, and the filtering function of the first capacitor and the second capacitor can be utilized to filter out noise signals possibly appearing in the circuit.

In addition, in the piezoresistive pressure sensing circuit according to the first aspect of the present disclosure, optionally, the first functional relationship and the second functional relationship are linear relationships, respectively. Therefore, the actual values of the first variable resistance element and the second variable resistance element can be accurately calculated.

A second aspect of the present disclosure provides a method for compensating for a pressure of a piezoresistive pressure sensing circuit, including: replacing a first variable resistance element and a second variable resistance element by a plurality of resistors with known resistance values, and calculating parameters of a first functional relation and a second functional relation according to a first functional relation between a measured value and an actual value of the first variable resistance value and a second functional relation between a measured value and an actual value of the second variable resistance value; measuring resistance values of the first variable resistance element and the second variable resistance element under a plurality of different temperatures and pressures, and finding actual values of the first variable resistance element and the second variable resistance element based on the first functional relationship, the second functional relationship, and the parameter; under different temperatures and pressures, calculating a third functional relation between the pressure and the temperature of the first variable resistor according to the real value of the first variable resistor element, and calculating a fourth functional relation between the pressure and the temperature of the second variable resistor according to the real value of the second variable resistor element, so as to calculate the temperature-to-resistance influence coefficient, the pressure-to-resistance influence coefficient and the temperature-to-sensitivity influence coefficient of the first variable resistor element and the second variable resistor element; and calculating a real blood pressure value based on the parameter, the temperature-to-resistance influence coefficient, the pressure-to-resistance influence coefficient, the temperature-to-sensitivity influence coefficient, the third functional relationship and the fourth functional relationship.

In the second aspect of the present disclosure, the true blood pressure value can be calculated more accurately based on the calculated parameters, the temperature-to-resistance influence coefficient, the pressure-to-resistance influence coefficient, and the temperature-to-sensitivity influence coefficient, the third functional relationship, and the fourth functional relationship.

In addition, compensation of piezoresistive pressure sensing circuit pressure according to a second aspect of the present disclosureIn the method, optionally, the third functional relationship and the fourth functional relationship are respectively: r ═ R₀+(1+k_T)^T+k_PP(1+k_S)^TWherein R is the true value of the first variable resistance element or the second variable resistance element, R₀Is an initial resistance value, k_TAs the temperature-dependent resistance coefficient, k_PFor the influence of pressure on the resistivity, k_ST is temperature, and P is pressure. Thus, the calculating unit can obtain an accurate blood pressure value according to the self characteristics (namely the functional relation) of the sensor.

In addition, in the compensation method for the pressure of the piezoresistive pressure sensing circuit according to the second aspect of the present disclosure, optionally, the first functional relationship and the second functional relationship are linear relationships, respectively. The actual values of the first variable resistive element and the second variable resistive element can be accurately calculated.

Drawings

Embodiments of the present disclosure will now be explained in further detail, by way of example only, with reference to the accompanying drawings, in which:

fig. 1 is a schematic view showing an intravascular pressure measurement catheter according to embodiment 1 of the present disclosure.

Fig. 2 is a block diagram schematically illustrating a piezoresistive pressure sensing circuit according to embodiment 1 of the present disclosure.

Fig. 3 is a circuit diagram showing an example of a specific configuration of the piezoresistive pressure sensing circuit according to embodiment 1 of the present disclosure.

Fig. 4 is a circuit diagram showing another example of the specific configuration of the piezoresistive pressure sensing circuit according to embodiment 1 of the present disclosure.

Fig. 5 is a flowchart illustrating a method of compensating for the pressure of the piezoresistive pressure sensing circuit according to embodiment 1 of the present disclosure.

Fig. 6 is a circuit diagram showing an example of a specific configuration of the piezoresistive pressure sensing circuit according to embodiment 2 of the present disclosure.

Fig. 7 is a circuit diagram showing another example of the specific configuration of the piezoresistive pressure sensing circuit according to embodiment 2 of the present disclosure.

Description of the symbols:

1 … intravascular pressure measuring catheter, 2 … piezoresistive pressure sensing circuit, 10(100) … sensing unit, 20 … flexible catheter, 30 … host computer, 31 … display, 200 … processing unit, 300 … calculating unit and 400 … storage unit.

Detailed Description

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, the same components are denoted by the same reference numerals, and redundant description thereof is omitted. The drawings are schematic and the ratio of the dimensions of the components and the shapes of the components may be different from the actual ones.

[ embodiment 1 ]

Fig. 1 is a schematic view showing an intravascular pressure measurement catheter 1 according to embodiment 1 of the present disclosure; fig. 2 is a block diagram schematically illustrating a piezoresistive pressure sensing circuit according to embodiment 1 of the present disclosure.

Referring to fig. 1 and 2, the piezoresistive pressure sensing circuitry to which the present disclosure relates may be applied in an intravascular pressure measurement catheter 1 as shown in fig. 1. The intravascular pressure measurement catheter 1 according to the present embodiment may include a sensing unit 10, a flexible catheter 20, and a host 30.

In this embodiment, the sensing unit 10 may be used for sensing a blood pressure value at a predetermined location within a blood vessel. The flexible catheter 20 may have a proximal portion 21 connected to the host 30 and a distal portion 22 connected to the proximal portion (see fig. 1). Additionally, the sensing unit 10 may be disposed within the distal portion 22 of the flexible catheter 20.

In some examples, host 30 may include a display 31 and manipulation buttons 32, among other things. The display 31 may be used to display the measured blood pressure value, and the control button 32 may include a switch and other buttons. In addition, the host 30 may further include a processing unit 200, a calculation unit 300, and a storage unit 400 (described later) that perform signal processing.

In practice, the flexible catheter 20 and the distal portion 22 of the flexible catheter 20 with the sensing unit 10 may be delivered to a predetermined location in the patient's body (e.g., vein, artery). Thus, a blood pressure measurement can be performed at the predetermined position (e.g., a lesion position), and the measured blood pressure value or the ratio of the blood pressure values (e.g., a blood flow reserve parameter) can be displayed on the display 31 of the host computer 30.

Referring to fig. 2, the piezoresistive pressure sensing circuit 2 according to the present disclosure may include a sensing unit 100 (i.e., the sensing unit 10 described above), a processing unit 200, a calculating unit 300, and a storage unit 400. As described above, the sensing unit 100 may be built into the distal portion 22 of the flexible catheter 20. In addition, the processing unit 200, the calculation unit 300, and the storage unit 400 may be built in the host 30. The sensing unit 100 may be connected to the host 30 using a wire or a flexible circuit board and transmit the measured blood pressure signal.

In some examples, the memory cell 400 may also be built into the sensing cell 100, or a portion of the memory cell 400 may be built into the sensing cell 100. Thereby, the compensation coefficient and the two-way variable resistance element (i.e., the first variable resistance element R) can be realized₁And a second variable resistance element R₂) One-to-one (described later in detail with the aid of fig. 4 and 7).

In some examples, the storage unit 400 may be implemented by means of a nonvolatile Memory, a Flash Memory (Flash Memory). In some examples, the memory unit 400 may also be, for example, a ferroelectric random access memory (FeRAM), a Magnetic Random Access Memory (MRAM), a phase change random access memory (PRAM), or a Resistive Random Access Memory (RRAM). This can reduce the possibility of data loss due to sudden power outage.

In other examples, the storage unit 400 may also be other types of readable storage media, such as Read-Only Memory (ROM), Random Access Memory (RAM), Programmable Read-Only Memory (PROM), Erasable Programmable Read-Only Memory (EPROM), One-time Programmable Read-Only Memory (OTPROM), Electrically Erasable rewritable Read-Only Memory (EEPROM), compact disc Read-Only Memory (CD-ROM) or other optical disc storage, magnetic disk storage, tape storage, or any other medium capable of being used to carry or store data. Thus, an appropriate memory can be selected according to different situations. In some examples, the memory unit 400 may be implemented using an EEPROM.

Fig. 3 is a circuit diagram showing an example of a specific configuration of the piezoresistive pressure sensing circuit 2 according to embodiment 1 of the present disclosure; fig. 4 is a circuit diagram showing another specific configuration of the piezoresistive pressure sensing circuit 2 according to embodiment 1 of the present disclosure.

With reference to fig. 3 and 4, the piezoresistive pressure sensing circuit 2 may be applied in an intravascular pressure measuring catheter 1, comprising: a sensing unit 100 for detecting blood pressure in a blood vessel and outputting a blood pressure signal, the sensing unit 100 including a first variable resistance element R₁And a second variable resistance element R₂The first variable resistance element R₁And a second variable resistance element R₂The resistance value of (a) is changed by changes in pressure and temperature; a processing unit 200 connected to the sensing unit 100 and receiving the measured blood pressure signal measured by the sensing unit 100 and processing the measured blood pressure signal; a storage unit 400 storing at least a compensation coefficient including temperature to the sensing unit 100, a compensation coefficient of pressure to the sensing unit 100, and a sensitivity compensation coefficient of temperature to the sensing unit 100, and including a first variable resistance element R₁First function relation of measured value and actual value of (1), second variable resistance element R₂A second functional relationship of the measured value of (a) to the actual value; and a calculation unit 300 which receives the measured blood pressure signal processed by the processing unit 200, and the compensation parameter and the functional relationship from the storage unit 400, and calculates a true blood pressure value based on the measured blood pressure signal, the compensation parameter, and the functional relationship.

In some examples, the sensing unit 100 may further include a third resistance element R₃And a fourth resistance element R₄First variable resistance element R₁And a second variable resistance element R₂Is connected to a power supply V, a first variable resistance element R₁And the other end of the third resistance element R₃Is connected with one end of the connecting rod; second variable resistance element R₂And the other end of the fourth resistance element R₄Is connected to a third resistive element R₃And the other end of the fourth resistance element R₄And is connected to ground (although an equipotential point may be set here, and the drawing is indicated by an equipotential symbol). Here, the first variable resistance element R may be formed of₁And a third resistance element R₃Constituting a voltage dividing circuit, in the first variable resistance element R₁The pressure change of the outside (such as blood vessel) is sensed to generate deformation, the deformation change is converted into an electric signal, and the electric signal is processed by a serial partial pressure calculation formulaOutputting a first variable resistance element R₁The pressure signal of (a); similarly, the second variable resistance element R₂And a fourth resistance element R₄A voltage divider circuit formed by a second variable resistance element R₂The pressure change of the outside (such as blood vessel) is sensed to generate deformation, and the formula is calculated through serial partial pressureOutput second variable resistance element R₂The pressure signal of (a).

Thus, the piezoresistive pressure sensing circuit can be based on two variable resistive elements (i.e., the first variable resistive element R)₁And a second variable resistance element R₂) The measured pressure signal and the externally applied temperature signal are solved simultaneously in the calculation unit 300 to obtain a pressure value and a temperature value (described later in detail).

In some examples, the processing unit 200 may include a first amplifier D₁A second amplifier D₂And analog-to-digital conversionADC, first amplifier D₁Input terminal of, second variable resistance element R₂And the other end of the fourth resistance element R₄Has a first connection terminal and a second connection terminal as input terminals and an output terminal, a first amplifier D₁The output end of the ADC is connected with a first connection end of the ADC; second amplifier D₁And a first variable resistance element R₁And the other end of the third resistance element R₃Is connected to one end of a second amplifier D₂The output end of the analog-to-digital converter is connected with a second connecting end of the analog-to-digital converter ADC; the output of the analog-to-digital converter ADC is the output of the processing unit 200. In the present embodiment, the intravascular pressure signal detected by the sensing unit 100 is amplified by an amplifier, and the analog electrical signal output by the sensing unit 100 is converted into a digital signal recognizable by the calculating unit 300 by an analog-to-digital converter ADC.

In some examples, the piezoresistive pressure sensing circuit 2 may further include a fifth resistive element R₅A sixth resistance element R₆A first capacitor C₁And a second capacitor C₂Fifth resistance element R₅And the other end of the second variable resistor R2 and the fourth resistance element R₄Is connected to a fifth resistive element R₅And the other end of the first capacitor C₁And a first amplifier D₁The input ends of the two-way valve are connected; a first capacitor C₁The other end of the first and second electrodes is grounded; sixth resistance element R₆And the first variable resistance element R₁And the other end of the third resistance element R₃Is connected to the sixth resistive element R₆And the other end of the first capacitor C₂And a second amplifier D₂The input ends of the two-way valve are connected; second capacitor C₂And the other end of the same is grounded.

In the present embodiment, the fifth resistance element R₅And a sixth resistance element R₆The current limiting circuit can play a role in current limiting and can be used for protecting a circuit from being broken down by larger current; a first capacitor C₁And a second capacitor C₂Can filter out the clutter signals of the branch where the branch is located, thereby enabling the measurementThe resulting blood pressure signal is more accurate.

In some examples, the piezoresistive pressure sensing circuit 2 may also include a third capacitance C₃Third capacitor C₃Can be used as an isolation capacitor to avoid two branches (i.e. the fifth resistor element R)₅And a sixth resistance element R₆Branch) of the voltage signals output by the voltage sensors, thereby enabling the output voltage signals to be more accurate.

In the present embodiment, the first functional relationship and the second functional relationship are linear relationships, respectively. Specifically, the first variable resistor R₁And a second variable resistor R₂Measured value R of₁、R₂And a first variable resistor R₁And a second variable resistor R₂True value of R₁'、R₂' following the following first and second functional relationships, respectively, the following equations (1) and (2):

in this embodiment, the first variable resistor R may be replaced by a resistor with a known resistance value₁And a second variable resistor R₂E.g. with R₃And R₄The first variable resistor R is replaced₁With R₅And R₆Replacing the second variable resistor R₂The following formulas (3) to (4) can be obtained:

R₅＝k₂ R₂₁+b₂… … type (5)

R₆＝k₂ R₂₂+b₂… … type (6)

Thereby, the parameter k in the first functional relation and the parameter k in the second functional relation can be solved simultaneously₁、b₁、k₂、b₂And the values are as follows:

therefore, a variable resistance element R can be accurately calculated according to the obtained parameters₁And a second variable resistance element R₂The true value of (d).

In the present embodiment, a compensation coefficient including temperature to the sensing unit 100, a compensation coefficient of pressure to the sensing unit 100, and a sensitivity compensation coefficient of temperature to the sensing unit 100 are stored through the memory unit 400, and a first variable resistance element R is included₁First function relation of measured value and actual value of (1), second variable resistance element R₂Thereby enabling the calculating unit 300 to obtain a correct blood pressure value based on the compensation coefficient and the function during calculation, and further improving the accuracy of the measurement of the intravascular blood pressure value.

In some examples, referring to fig. 4, the memory 400 may also be placed together with the sensing unit 100, thereby enabling the compensation coefficient and the first variable resistance element R to be implemented₁And a second variable resistance element R₂One-to-one correspondence.

Hereinafter, a method of compensating for a pressure of a piezoresistive pressure sensing circuit according to an embodiment of the present disclosure will be described with reference to the drawings.

Fig. 5 is a flow chart illustrating a method of compensating for piezoresistive pressure sensing circuit pressure in accordance with an embodiment of the present disclosure.

Referring to fig. 5, the present disclosure provides a method of compensating for piezoresistive pressure sensing circuit pressure, comprising: replacing the first variable resistive element R with a plurality of resistors of known resistance₁And a second variable resistance element R₂And based on the measured value of the first variable resistance value (R as described above)₁) With true value (R as described above)₁') a first functional relationship, a measured value of a second variable resistance value (R as described above)₂) With true value (R as described above)₂') and calculating parameters (k as described above) of the first and second functional relationships₁、b₁、k₂、b₂) (step S100); the resistance values of the first variable resistance element R1 and the second variable resistance element R2 are measured under a plurality of different temperatures and pressures, and the first variable resistance element R is found based on the first functional relationship, the second functional relationship, and the parameters₁And a second variable resistance element R₂True value of (step S200); and calculating the first variable resistance R from the actual values of the first variable resistance element R1 under a plurality of different temperatures and pressures₁According to a third function of the pressure and temperature of the second variable resistive element R₂Calculating the second variable resistance R according to the true value of₂Is calculated as a fourth function of the pressure and temperature, thereby calculating the first variable resistive element R₁And a second variable resistance element R₂Temperature-to-resistance influence coefficient, pressure-to-resistance influence coefficient, and temperature-to-sensitivity influence coefficient (step S300); and calculating a real blood pressure value based on the parameters, the temperature-to-resistance influence coefficient, the pressure-to-resistance influence coefficient, the temperature-to-sensitivity influence coefficient, the third functional relationship and the fourth functional relationship (step S400).

In the compensation method according to the present embodiment, the actual blood pressure value can be calculated more accurately based on the calculated parameters, the temperature-to-resistance influence coefficient, the pressure-to-resistance influence coefficient, and the temperature-to-sensitivity influence coefficient, the third functional relationship, and the fourth functional relationship.

Specifically, in the compensation method for the pressure of the piezoresistive pressure sensing circuit according to the present disclosure, the third functional relationship and the fourth functional relationship are respectively expressed by the following formula (7):

R＝R₀+(1+k_T)^T+k_PP(1+k_S)^T… … type (7)

Wherein R is a first variable resistance element R₁Or a second variable resistance element R₂True value of R₀Is an initial resistance value, k_TAs the temperature-dependent resistance coefficient, k_PFor the influence of pressure on the resistivity, k_ST is temperature, and P is pressure. In addition, the first functional relationship and the second functional relationship are linear relationships respectively. It should be noted that, since the temperature T and the pressure P externally applied to the intravascular pressure measurement catheter 1 are the same, the third functional relationship and the fourth functional relationship may follow the same functional formula (i.e., formula 7).

In step S100, the first variable resistive element R may be replaced with a plurality of resistors of known resistance values, as described above₁And a second variable resistance element R₂And calculating parameters of the first functional relationship and the second functional relationship according to a first functional relationship between the measured value of the first variable resistance value and the actual value and a second functional relationship between the measured value of the second variable resistance value and the actual value (the specific calculation process refers to the foregoing and is not described herein again).

In step S200, the first variable resistance element R can be determined from the parameters calculated in step S1 and the first and second functional relationships, that is, by substituting the parameters into the first and second functional relationships₁And a second variable resistance element R₂The true value of (d).

In step S300, for example, a plurality of temperature points and pressure points may be collected by simulating a physiological environment in a human body at the outside. Specifically, the pressure measuring tube 1 may be placed in a transverse warm water bath or a constant pressure water bath to control the temperature and pressure of the outside. In the present embodiment, for example, the pressure measurement tube 1 may be first placed at a constant temperature T₁In the water bath, and the pressure is controlled to be P₁And P₂Bring it intoThe third functional relationship and the fourth functional relationship can be expressed by the following formulas (8) and (9):

at the same time, the pressure measuring catheter 1 can be placed again at a constant temperature T₂In the water bath, and the pressure is controlled to be P₁And P₂And substituting the third functional relation and the fourth functional relation into the third functional relation and the fourth functional relation to obtain the following formulas (10) and (11):

it should be noted that, according to the characteristics of the pressure measurement catheter 1 itself, the degree of influence of temperature on the resistance is much larger than the degree of influence of pressure on the resistance, and the degree of influence of pressure on the resistance is much larger than the degree of influence of temperature on the sensitivity, so based on the above four equations (8) to (11), the equation (10) is divided by the equation (8) and the equation (11) is divided by the equation (9), and the average value is obtained:

according to (2) - (1) + (4) - (3):

according to ((4) - (3))/((2) - (1)), the following results were obtained:

in step 400, the temperature-dependent coefficient of resistance K may be determined based on the above parameters_TPressure on resistance coefficient of influence K_PAnd the temperature-sensitivity coefficient of influence K_SAnd calculating a real blood pressure value according to the third functional relation and the fourth functional relation.

Specifically, as described above, when the pressure measurement catheter 1 is used for intravascular pressure detection, the pressure signal measured by the sensing unit 100 is amplified by the processing unit 200 and processed by analog-to-digital conversion (analog signal is converted into digital signal), and then enters the calculating unit 300, and at this time, the calculating unit 300 may calculate a true blood pressure value by calling the parameters and the compensation coefficients stored in the storage unit 400, and display the true blood pressure value on the display 31. This can further improve the accuracy of the measurement of the intravascular blood pressure value.

[ 2 nd embodiment ]

Fig. 6 is a circuit diagram showing an example of a specific configuration of the piezoresistive pressure sensing circuit 2 according to embodiment 2 of the present disclosure; fig. 7 is a circuit diagram showing another example of the specific configuration of the piezoresistive pressure sensing circuit 2 according to embodiment 2 of the present disclosure.

The main difference between this embodiment and embodiment 1 is that the position of the sensing unit 100 can be flexibly set in the third resistor R₃And a fourth resistor R₄On the other side (third resistor R as shown in fig. 6 and 7)₃And a fourth resistor R₄The lower side of) the optical disk. Hereinafter, the above-described different points will be mainly described in detail.

In the present embodiment, as shown in fig. 6, the first variable resistor R is located differently from the variable resistor of embodiment 1₁And a second variable resistor R₂Are respectively arranged at the third resistors R₃And a fourth resistor R₄The other side (lower side in fig. 6). In particular, the third resistor R₃And a fourth resistor R₄Is connected in parallel to a power supply VThree resistors R₃And the other end of the first variable resistor R₁Is connected with one end of the connecting rod; a fourth resistor R₄And the other end of the second variable resistor R and the second variable resistor R₂Is connected with one end of the connecting rod; first variable resistor R₁And the other end of the second variable resistor R and the second variable resistor R₂The other end of the first and second electrodes is connected to ground.

Here, the third resistance element R may be provided₃And a first variable resistance element R1 constituting a voltage dividing circuit, the first variable resistance element R₁The pressure change of the outside (such as blood vessel) is sensed to generate deformation, the deformation change is converted into an electric signal, and the electric signal is processed by a serial partial pressure calculation formulaOutputting a first variable resistance element R₁The pressure signal of (a); similarly, the second variable resistance element R₂And a fourth resistance element R₄A voltage divider circuit formed by a second variable resistance element R₂The pressure change of the outside (such as blood vessel) is sensed to generate deformation, and the formula is calculated through serial partial pressureOutput second variable resistance element R₂The pressure signal of (a).

Also, on the basis of fig. 6, referring to fig. 7, it is possible to place a memory EEPROM together with the sensing unit 100, thereby enabling the compensation coefficient and the first variable resistive element R to be realized₁And a second variable resistance element R₂One-to-one correspondence.

While the invention has been specifically described above in connection with the drawings and examples, it will be understood that the above description is not intended to limit the invention in any way. Those skilled in the art can make modifications and variations to the present invention as needed without departing from the true spirit and scope of the invention, and such modifications and variations are within the scope of the invention.