Piezoelectric sensor sensing circuit, medical catheter and medical monitoring system

Abstract

The present application discloses a piezoresistive sensor sensing circuit, a medical catheter and a medical monitoring system. Among them, the sensing circuit includes: a temperature measurement unit, including a diode or an NTC resistor, for measuring the temperature near the piezoresistive sensor through the diode or the NTC resistor to obtain a temperature signal; a bridge unit, for detecting a pressure signal near the piezoresistive sensor and outputting a differential voltage based on the pressure signal; a calculation and processing unit, connected to the bridge unit and the temperature measurement unit, for performing temperature compensation on the differential voltage based on the temperature signal to obtain the compensated pressure signal. The present application solves the technical problem of low accuracy of piezoresistive sensors in the related art.

Description

Technical Field

[0001] The present application relates to the field of medical devices, and in particular, to a piezoresistive sensor sensing circuit, a medical catheter, and a medical monitoring system. Background Art

[0002] For the measurement of pressure inside the human body, most of the piezoresistive sensors used are piezoresistive. During application, it is most important to ensure the linearity of the piezoresistive sensor to pressure and the calibration of the influence of temperature on its zero error and full-scale error.

[0003] Due to the manufacturing process of the sensor, when some Wheatstone bridge piezoresistive sensors measure pressure, they will be affected by the non-linearity of the sensor itself to pressure and the chip ambient temperature. In addition, the sensor itself will also have a zero offset, and different zero offsets make it difficult to unify the sensor output.

[0004] In addition, general piezoresistive sensors in the form of Wheatstone bridges have zero error and full-scale error that vary with temperature. If high measurement accuracy is required, it cannot be ignored. Moreover, the existing piezoresistive sensor sensing circuit lacks a protection circuit for transient voltage and electrostatic discharge, and the temperature inside the body cannot be directly measured by the temperature sensor integrated on the IC.

[0005] In view of the above problems, no effective solution has been proposed yet. Summary of the Invention

[0006] Embodiments of the present application provide a piezoresistive sensor sensing circuit, a medical catheter, and a medical monitoring system to at least solve the technical problem of low accuracy of piezoresistive sensors in related technologies.

[0007] According to one aspect of the embodiments of the present application, a piezoresistive sensor sensing circuit is provided, including: a temperature measurement unit, including a diode or an NTC resistor, configured to measure the temperature near the piezoresistive sensor through the diode or the NTC resistor to obtain a temperature signal; a bridge unit, configured to detect a pressure signal near the piezoresistive sensor and output a differential voltage based on the pressure signal; a calculation and processing unit, connected to the bridge unit and the temperature measurement unit, configured to perform temperature compensation on the differential voltage based on the temperature signal to obtain the compensated pressure signal.

[0008] According to another aspect of the embodiments of the present application, a medical catheter is further provided, including: a catheter body; the sensing circuit as described above.

[0009] According to another aspect of the embodiments of the present application, there is also provided a medical monitoring system, including the above-mentioned medical catheter; a monitoring device for monitoring and displaying the data detected by the sensing circuit when the medical catheter is inserted into the body of the monitored object.

[0010] According to another aspect of the embodiments of the present application, there is also provided a method for compensating the pressure signal of a piezoresistive sensor, including measuring the temperature near the piezoresistive sensor through the temperature measurement unit of the piezoresistive sensor to obtain a temperature signal; detecting the pressure signal near the piezoresistive sensor through the bridge unit of the piezoresistive sensor and outputting a differential voltage based on the pressure signal; performing temperature compensation on the differential voltage based on the temperature signal to obtain the compensated pressure signal.

[0011] In the embodiments of the present application, compensating the pressure signal detected by the piezoresistive sensor solves the technical problem of low accuracy of the piezoresistive sensor in the related art. Description of the Drawings

[0012] The drawings described herein are used to provide a further understanding of the present application, and constitute a part of the present application. The schematic embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation to the present application. In the drawings:

[0013] Figure 1 is a schematic structural diagram of a sensing circuit of a piezoresistive sensor according to an embodiment of the present application;

[0014] Figure 2 is a schematic structural diagram of another sensing circuit of a piezoresistive sensor according to an embodiment of the present application; The alarm interruption unit should be within the calculation and processing unit

[0015] Figure 3 is a schematic structural diagram of a sensing circuit for measuring temperature using a diode according to an embodiment of the present application;

[0016] Figure 4 is a schematic circuit diagram of a circuit protection unit according to an embodiment of the present application;

[0017] Figure 5 is a schematic circuit diagram of a temperature measurement unit and a calculation and processing unit using a diode according to an embodiment of the present application;

[0018] Figure 6A is a schematic circuit diagram of a sensing circuit for measuring temperature using an NTC resistor according to an embodiment of the present application;

[0019] Figure 6B is a schematic circuit diagram of a temperature measurement unit and a calculation and processing unit using an NTC resistor according to an embodiment of the present application;

[0020] Figure 7 It is a schematic circuit diagram of a sensing circuit for measuring temperature using a bridge unit according to an embodiment of the present application;

[0021] Figure 8A It is a schematic structural diagram of a sensing circuit according to an embodiment of the present application;

[0022] Figure 8B It is a schematic structural diagram of another sensing circuit according to an embodiment of the present application;

[0023] Figure 8C It is a schematic structural diagram of a medical catheter according to an embodiment of the present application;

[0024] Figure 9 It is a schematic structural diagram of a medical monitoring system according to an embodiment of the present application;

[0025] Figure 10 It is a flowchart of a method for compensating the pressure signal of a piezoresistive sensor according to an embodiment of the present application;

[0026] Figure 11 It is a schematic diagram of the effects before and after calibration for calibrating pressure using temperature according to an embodiment of the present application. Detailed implementation manners

[0027] In order to enable those skilled in the art to better understand the solution of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0028] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily need to describe a specific order or sequence. It should be understood that such used data can be interchanged under appropriate circumstances so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0029] Embodiment 1

[0030] According to an embodiment of the present application, a piezoresistive sensor sensing circuit is provided, as Figure 1 shown. The sensing circuit includes: a temperature measurement unit 12, a bridge unit 14, and a calculation and processing unit 16.

[0031] The temperature measurement unit 12 includes a diode or an NTC resistor, and is configured to measure the temperature near the piezoresistive sensor through the diode or the NTC resistor to obtain a temperature signal. The temperature measurement unit 12 may include: a diode D1, with both ends of the diode D1 connected to both ends of the calculation and processing unit 16; or, it includes a fifth resistor R5, a sixth resistor element R6, or a second capacitor element R7. Wherein, one end of the fifth resistor R5 is connected to the calculation and processing unit 16, and the other end is respectively connected to one end of the sixth resistor R6 and one end of the second capacitor C2. The other end of the second capacitor C2 is connected to the other end of the sixth resistor R6, and the other end of the sixth resistor R6 is connected to the calculation and processing unit 16. Wherein, the sixth resistor R6 is the NTC resistor.

[0032] The bridge unit 14 is configured to detect a pressure signal near the piezoresistive sensor and output a differential voltage based on the pressure signal. The bridge unit 14 includes: a sensing unit and a fixed resistor unit. The sensing unit includes a variable resistor element, and is configured to detect the pressure near the piezoresistive sensor and output a pressure signal; the fixed resistor unit is connected to the sensing unit and is configured to form a Wheatstone bridge with the variable resistor element to collect the differential voltage. In one example, the variable resistor element of the sensing unit includes a first variable resistor RP1 and a second variable resistor RP2.

[0033] In some examples, the bridge unit 14 includes a tenth resistor R10 and an eleventh resistor R11. One end of the tenth resistor R10 and one end of the eleventh resistor R11 are connected in series. The other end of the tenth resistor R10 is connected to the other end of the first variable resistor RP1 via the second magnetic bead FB2, and the other end of the eleventh resistor R11 is connected to the other end of the second variable resistor RP2 via the third magnetic bead FB3.

[0034] The calculation and processing unit 16 is connected to the bridge unit 14 and the temperature measurement unit 12, and is configured to perform temperature compensation on the differential voltage based on the temperature signal to obtain the compensated pressure signal. The calculation and processing unit 16 outputs the compensated pressure signal as a proportional voltage, or outputs it digitally in SENT protocol, or outputs it in PWM, or outputs it in I2C.

[0035] The second port of the computing and processing unit 16 is grounded, the first port is connected to a power supply, the fourth port is connected to one end of the bridge unit 14 through a fourth resistor R4 and a third resistor R3, the sixth port is connected to the other end of the bridge unit 14 through a ninth resistor R9 and an eighth resistor R8, and the fifth port is connected to the power supply port of the bridge unit 14 through a second resistor R2 and a first resistor R1.

[0036] The computing and processing unit 16 can also calibrate the piezoresistive sensor for pressure and zero offset to obtain the compensation relationship; then, based on the compensation relationship and the differential voltage, compensate the piezoresistive sensor for zero error and full-scale error varying with temperature.

[0037] For example, calibrate the piezoresistive sensor under known temperature and pressure to obtain the influence coefficient of pressure on the bridge, the influence coefficient of temperature on sensitivity, the influence coefficient of zero offset, and the influence coefficient of linearity on pressure; based on the influence coefficient of pressure on the bridge, the influence coefficient of temperature on sensitivity, the influence coefficient of zero offset, and the influence coefficient of linearity on pressure, perform zero offset compensation, linear compensation, and temperature compensation on the differential voltage. Among them, the influence coefficient of pressure on the bridge includes at least one of the following: the initial sensitivity gain Gain of the bridge unit under unit pressure A ; the influence coefficient of temperature on sensitivity includes at least one of the following: the temperature coefficient TC of the sensitivity of the bridge unit gain and the temperature quadratic term coefficient SOT of the sensitivity of the bridge unit tcg ; the influence coefficient of zero offset includes at least one of the following: the compensation B for the bridge offset generated by the piezoresistive sensor after calibration shift the compensation zero error Offset of the original measurement reading of the bridge unit B the temperature coefficient TC for the zero point offst and the temperature correction quadratic term coefficient SOT tco ; the influence coefficient of linearity on pressure includes: the quadratic term coefficient SOT for non-linear correction of bridge reading B .

[0038] In one example, the computing and processing unit 16 is further configured to: under multiple different temperatures and pressures, calculate the first functional relationship between pressure and temperature of the first variable resistor according to the true value of the first variable resistor of the sensing unit 12, and calculate the second functional relationship between pressure and temperature of the second variable resistor according to the true value of the second variable resistor element of the sensing unit 12. Among them, the first and second functional relationships are respectively:

[0039] R1 = (1 + k s1 · ΔT) · kp1 ·P + R0 + k T1 ·ΔT (1)

[0040] R2 = (1 + k s2 ·ΔT)·k p2 ·P + R0 + k T2 ·ΔT (2)

[0041] Wherein, R1 and R2 are the true values of the first variable resistor and the second variable resistor respectively, r0 is the initial value, for example, the initial resistance value at 25 degrees Celsius under a standard atmospheric pressure, k p1 、k p2 are respectively the pressure-to-resistance influence coefficients representing the influence of pressure on the first variable resistor and the second variable resistor, k s1 、k s2 are respectively the temperature-to-sensitivity influence coefficients representing the influence of temperature on the sensitivity of the first variable resistor and the second variable resistor, k T1 、k T2 are respectively the temperature-to-resistance influence coefficients representing the influence of temperature on the resistance values of the first variable resistor and the second variable resistor, ΔT is the relative temperature change value, and P is the pressure.

[0042] In one example, the calculation and processing unit may also be connected to a display unit for displaying the compensated pressure signal output on the display unit.

[0043] In one example, the calculation and processing unit further includes an alarm and interruption unit for alarming when the compensated pressure signal exceeds the pressure threshold or the compensated temperature signal exceeds the temperature threshold, and performing short-circuit power-off protection on the sensing circuit.

[0044] In one example, the sensing circuit further includes a circuit protection unit, which is connected to the sensing unit and the calculation and processing unit 16 for performing electrostatic discharge protection on the sensing unit and the calculation and processing unit 16.

[0045] In one example, the sensing circuit further includes a spike interference suppression unit 11. The spike interference suppression unit 11 is connected between the sensing unit and the fixed resistor unit for filtering spike interference in the pressure signal; the spike interference suppression unit 11 includes a first magnetic bead FB1, a second magnetic bead FB2, and a third magnetic bead FB3, wherein one end of the first magnetic bead FB1 is connected to the calculation and processing unit 16 via a first resistor R1, and the other end is respectively connected to one ends of the first variable resistor RP1 and the second variable resistor RP2.

[0046] In one example, the sensing circuit further includes a filtering unit 13, connected before the bridge unit 14 and the calculation and processing unit 16, for filtering out the noise in the differential voltage. For example, the filtering unit 13 includes a fourth resistor R4, a ninth resistor R9, a third capacitor C3, a fourth capacitor C4, and a fifth capacitor C5. One end of the fourth resistor R4 is connected to the calculation and processing unit 16, and the other end is connected to the bridge unit 14. One end of the ninth resistor R9 is connected to the calculation and processing unit 16, and the other end is connected to the bridge unit 14. One end of the fourth capacitor C4 is connected to the fourth resistor R4 and the calculation and processing unit 16, and the other end is grounded. One end of the fifth capacitor C5 is connected to the ninth resistor R9 and the calculation and processing unit 16, and the other end is grounded. One end of the third capacitor C3 is connected to the fourth capacitor C4, and the other end is connected to the fifth capacitor C5.

[0047] Since the sensitivity and zero - output offset of the piezoresistive sensor cannot be completely unified, the detected pressure is inaccurate. The sensing circuit provided in this embodiment can calibrate and measure the piezoresistive sensor, and can compensate the pressure signal based on the temperature near the piezoresistive sensor, thereby improving the accuracy of the piezoresistive sensor.

[0048] Embodiment 2

[0049] According to an embodiment of the present application, there is also provided a piezoresistive sensor sensing circuit, which is applied to a medical catheter to measure human blood pressure, bladder pressure, intracranial pressure, etc. As Figure 2 shown, the sensing circuit includes: a temperature measurement unit 12, a bridge unit 14, a spike interference suppression unit 11, a filtering unit 13, a calculation and processing unit 16, a circuit protection unit (not shown), an alarm and interruption unit 162, and a storage unit 10.

[0050] The bridge unit 14 includes a sensing unit 142 and a fixed - resistor unit 144. The sensing unit 142 is used to detect the pressure in the environment and output a pressure signal, and includes a first pressure - sensing component having a first variable - resistance element RP1 and a second pressure - sensing component having a second variable - resistance element RP2. The resistance values of the first variable - resistance element and the second variable - resistance element change with pressure and temperature.

[0051] The fixed resistor unit 144 is used to form a complete Wheatstone bridge with the front-end variable resistor elements (i.e., the first variable resistor element RP1 and the second variable resistor element RP2). In one example, the fixed resistor unit 144 includes an eleventh resistor element and a tenth resistor element. One end of the first variable resistor element and one end of the second variable resistor element are connected and connected to the processing chip U1. The other end of the first variable resistor element is connected to one end of the eleventh resistor element; the other end of the second variable resistor element is connected to one end of the tenth resistor element, and the other end of the eleventh resistor element is connected to the other end of the tenth resistor element and grounded.

[0052] The spike interference suppression unit 11 is connected to the sensing unit 142 and the fixed resistor unit 144. In one example, the spike interference suppression unit 11 includes a first bead element, a second bead element, and a third bead element. One end of each bead is connected to the Wheatstone bridge, and the other end is connected to a first resistor. The second bead is connected to the first variable resistor element and the eleventh resistor element, and the third variable bead is connected to the second variable resistor element and the tenth resistor element.

[0053] The filtering unit 13 is connected to the bridge unit 14 and the calculation processing unit 16, and is used to filter out noises other than the pressure signal. In one example, the filtering unit 13 includes a fourth resistor element, a ninth resistor element, a third capacitor element, a fourth capacitor element, and a fifth capacitor element. One end of the fourth resistor element is connected to the processing unit, and the other end is connected to the Wheatstone bridge. One end of the ninth resistor element is connected to the processing unit, and the other end is connected to the Wheatstone bridge. One end of the fourth capacitor element is connected to the fourth resistor and the processing unit, and the other end is grounded. One end of the fifth capacitor element is connected to the fourth resistor and the processing unit, and the other end is grounded. One end of the third capacitor element is connected to the fourth capacitor element, and one end is connected to the fifth capacitor element.

[0054] The temperature measurement unit 12 senses through an external diode or an external NTC resistor and transmits the sensed temperature signal to the calculation processing unit 16. The temperature measurement unit 12 can sense through an external diode or an external NTC resistor and transmit the sensed temperature signal to the calculation processing unit 16. The diode D1 of the temperature sensing unit is connected to both ends and connected to the calculation processing unit 16, and the calculation processing unit 16 can be a chip. In one example, the temperature measurement unit 12 includes a fifth resistor element, a sixth resistor element, a second capacitor element, and a chip U1. One end of the fifth resistor element is connected to the chip U1, and the other end is connected to the sixth resistor element and the second capacitor element. The second capacitor element is connected to the sixth resistor element, and one end of the sixth resistor element is connected to the fifth resistor element, and the other end is connected to the chip U1. Among them, the sixth resistor element is an NTC thermistor resistor element.

[0055] The storage unit 10 stores at least a compensation coefficient of temperature for the sensing unit, a compensation coefficient of pressure for the sensing unit, and a sensitivity compensation coefficient of temperature for the sensing unit.

[0056] The calculation and processing unit 16 includes a processing unit and a calculation unit. The processing unit is connected to the sensing unit 142 and receives the blood pressure signal measured by the sensing unit 142, and processes the measured blood pressure signal; the calculation unit, connected to the bridge unit 14, receives the blood pressure signal processed by the processing unit, and calculates the true pressure value based on the compensation relationship stored in the storage unit 10.

[0057] The second port of the processing unit is grounded, the first port is connected to the power supply, the fourth port is connected to one end of the Wheatstone bridge through a fourth resistor element and a third resistor element, the sixth port is connected to the other end of the Wheatstone bridge through a ninth resistor element and an eighth resistor element, and the fifth port is connected to the power supply port of the Wheatstone bridge through a second resistor element and a first resistor element; the processing unit includes a low-noise preamplifier, an analog-to-digital converter, and a digital signal processing circuit, and the signal passing through the digital signal processing circuit is used as the output terminal of the processing unit.

[0058] The circuit protection unit is connected to the sensing unit and the calculation unit for electrostatic discharge protection of the circuit. The circuit protection unit includes chip U2, a first resistor element, a third resistor element, and an eighth resistor element. One end of the first resistor element is connected to a first bead element, and the other end is connected to the first port of chip U2. One end of the third resistor element is connected to the second port of chip U2, and the other end is connected to the Wheatstone bridge. One end of the eighth resistor element is connected to the fourth port of chip U2, and the other end is connected to the Wheatstone bridge. The fifth port of chip U2 is connected to the power supply, and the third port of chip U2 is grounded.

[0059] The alarm and interruption unit 162 alarms for pressures or temperatures exceeding expectations, and at the same time performs short-circuit power-off protection. The alarm and interruption unit can be programmed and configured internally through chip U1, and the alarm signal can be output through the chip itself to achieve the alarm function; when a short circuit of the bridge is detected, the interruption unit can interrupt the power supply to the bridge.

[0060] The calculation and processing unit can be connected to an external display unit. Based on the result of the calculation unit, the display unit displays the measured pressure and temperature on the screen of the display unit. In one example, the display unit includes a single-chip microcomputer processing module and a display screen module, and can display the measured ambient pressure and temperature at the same time. The single-chip microcomputer is used to match the signal output by the calculation unit with the numerical value displayed on the display screen.

[0061] The storage unit 10 is provided inside the computing and processing unit 16. The storage unit can be a read-only memory, a random access memory, etc.

[0062] In this embodiment, based on the temperature measured by the temperature measurement unit, temperature compensation is performed on the pressure signal measured by the sensing unit, so that the obtained pressure value is more accurate.

[0063] Embodiment 3

[0064] According to an embodiment of the present application, a piezoresistive sensor sensing circuit is also provided. The sensing circuit of this embodiment collects the pressure and temperature in the human body environment through the front-end sensing unit, and transmits the collected data to the computing and processing unit. Then, the collected data is processed and output according to the compensation relationship stored in the storage unit, and finally the environmental pressure and temperature are displayed on the display unit.

[0065] Figure 3 It is a schematic structural diagram of a sensing circuit that uses a diode for temperature measurement according to an embodiment of the present application. Figure 3 The sensing circuit in can be divided into a bridge unit, a spike interference suppression unit, a filtering unit, a temperature measurement unit, a computing and processing unit, and a circuit protection unit.

[0066] Next, it will be combined with Figure 2 and Figure 3 to describe in detail the specific structures of each component.

[0067] The bridge unit 14 is powered by a constant voltage or constant current or intermittent power supply through the U1.5 port, or is powered by an externally connected intermittent power supply. The components that make up the bridge unit 14 are the piezoresistive resistors RP1, RP2 and the fixed resistors R11, R12. When the pressure or temperature changes, the resistance values of the variable resistors RP1 and RP2 change, so that the differential voltage magnitude at the U1.4 and U1.6 ports changes. The voltages at both ends of the bridge are respectively input into the chip U1 through U1.4 and U1.6. The differential voltages collected at U1.4 and U1.6 inside U1 are processed (including zero-offset compensation, linear compensation, temperature compensation) and then digitally output. The resistors R4, R9, and the capacitors C3, C4, C5 are filtering resistors and capacitors. The resistors R1, R3, R8 and U2 form a discharge protection unit.

[0068] Figure 4 It is a schematic structural diagram of the circuit protection unit according to an embodiment of the present application. As Figure 4 shown, the circuit protection unit is the chip U2 in this embodiment. The fifth port of the chip U2 is connected to the power supply, the third port is grounded, and the first, second, and fourth ports are respectively connected to the power supply terminal U2.1, the bridge signal acquisition terminal U2.2, and U2.4 of the bridge unit 14 for protecting the electrostatic discharge of the circuit.

[0069] Figure 5 It is a schematic structural diagram of the calculation processing unit 16 according to an embodiment of the present application. As Figure 5 shown, the calculation processing unit 16 is the chip U1 in this embodiment. The chip U1 is powered by an external power supply, powers the bridge unit 14, and processes the differential voltage signal input by the bridge unit 14. The chip U1 can measure the temperature through an externally connected temperature measuring diode, and can output the processed true pressure value through the Out port.

[0070] The storage unit can store values such as the compensation gain (sensitivity) of the bridge unit, the zero compensation error of the bridge, the temperature coefficient of the bridge sensitivity, the temperature coefficient of the bridge zero point, and the correction quadratic term coefficient. In this embodiment, the storage unit can be set in the calculation processing unit, and in other embodiments, it can also be set outside the calculation processing unit.

[0071] The calculation processing unit will be described in detail below.

[0072] First, by measuring the bridge output values at different temperatures and pressures, data such as the compensation gain (sensitivity) of the original measurement readings of the sensor bridge, the compensation zero error of the original measurement readings of the sensor bridge, the temperature coefficient of the sensor bridge sensitivity, and the temperature coefficient of the sensor bridge zero point can be obtained. For example, at the reference temperature, by measuring the output value changes of the piezoresistive sensor at zero pressure and full pressure, the compensation gain (sensitivity) data of the original measurement readings of the sensor bridge can be obtained; by measuring the zero output of the sensor bridge, the compensation zero error of the original measurement readings of the sensor bridge can be obtained; by measuring the values of zero pressure and full pressure at different temperatures, the temperature coefficient of the sensor bridge sensitivity can be obtained, and so on.

[0073] After obtaining the above compensation relationships, the following correction formula based on the piezoresistive sensor bridge parabola can be used to compensate the differential voltage. Specifically, the formula for sensor bridge parabola correction is:

[0074] B tmp =Gain B ·(1 + TC gain ·ΔT + SOT tcg ·ΔT 2 )·(K·U·Gain A -Offset B +TC offset ·ΔT + SOT tco ·ΔT 2 ) (3)

[0075] B=(B tmp ·(1 + |B tmp |·SOT B) + 1) + B shift (4)

[0076] Among them, Gain A is the initial sensitivity gain of the bridge under unit pressure; U is the differential voltage small; K is the quantization level processing coefficient of analog-to-digital conversion; B is the reading of the bridge unit of the calibrated piezoresistive sensor; B tmp is the intermediate calculation result of the reading of the bridge unit of the piezoresistive sensor; B shift is the compensation for the bridge unit offset generated after calibration or encapsulation of the piezoresistive sensor; Gain B is the compensation gain (sensitivity) of the original measurement reading of the bridge unit of the piezoresistive sensor; Offset B is the compensation zero error of the original measurement reading of the bridge unit 14 of the piezoresistive sensor; TC gain is the temperature coefficient of the sensitivity of the bridge unit 14 of the piezoresistive sensor; TC offst is the temperature coefficient of the zero point of the bridge unit 14 of the piezoresistive sensor; SOT tcg is for TC gain temperature correction quadratic term coefficient; SOT tco is for TC offst temperature correction quadratic term coefficient; SOT B is the quadratic term coefficient for non-linear correction of the bridge reading, T represents the set base temperature, and ΔT represents the difference between the actual temperature and the base temperature.

[0077] In another example, another calibration formula based on the S-shaped curve of the piezoresistive sensor bridge can be adopted:

[0078] B tmp = Gain B ·(1 + TC gain ·ΔT + SOT tcg ·ΔT 2 )·(K·U·Gain A - Offset B + TC offst ·ΔT + SOT tco ·ΔT 2 ) + 1 (5)

[0079] B = (B tmp ·(1 + B tmp ·SOT B )) + B shift (6)

[0080] Among them, Gain AInitial sensitivity gain of the bridge under unit pressure; P is the magnitude of the pressure; K1 and A are quantization level processing coefficients for analog-to-digital conversion; B is the reading of the bridge unit of the calibrated piezoresistive sensor; B tmp Is the intermediate calculation result of the reading of the bridge unit of the piezoresistive sensor; B shift Is the compensation for the bridge unit offset generated by the piezoresistive sensor after calibration or encapsulation; Gain B Is the compensation gain (sensitivity) for the original measurement reading of the bridge unit of the piezoresistive sensor; Offset B Is the compensation zero error for the original measurement reading of the bridge unit of the piezoresistive sensor; TC gain Is the temperature coefficient of the sensitivity of the bridge unit of the piezoresistive sensor; TC offst Is the temperature coefficient of the zero point of the bridge unit of the piezoresistive sensor; SOT tcg Is for TC gain Quadratic term coefficient for temperature correction; SOT tco Is for TC offst Quadratic term coefficient for temperature correction; SOT B Is the quadratic term coefficient for non-linear correction of the bridge reading.

[0081] This embodiment has the following beneficial effects:

[0082] This embodiment calibrates the pressure and zero offset of each piezoresistive sensor and stores the obtained compensation relationship after calibration, and then compensates for the zero error and full-scale error of the piezoresistive sensor with temperature change and stores them, so as to achieve normalized output.

[0083] This embodiment can suppress high-frequency noise and spike interference in the circuit and perform filtering processing, and can also provide electrostatic discharge protection for the sensing circuit itself.

[0084] This embodiment can directly measure the temperature near the piezoresistive sensor through an external diode or an external NTC resistor.

[0085] The sensing circuit in this embodiment can output signals in various forms (such as proportional voltage output, SENT protocol digital output, PWM output, and I2C output), and display the pressure and temperature on the screen, so that the pressure and temperature information can be obtained more conveniently. In addition, this embodiment also provides an alarm function and an interrupt function.

[0086] Embodiment 4

[0087] According to the embodiment of the present application, a piezoresistive sensor sensing circuit is also provided. Figure 6A Is a schematic structural diagram of a sensing circuit that uses an NTC resistor to measure temperature according to the embodiment of the present application. Figure 6AThe sensing circuit in [description] except for the structure of the temperature measurement unit and Figure 3 is different from that in [description], and the other structures are similar. Therefore, the other structures will not be described in detail here.

[0088] Figure 6B is a schematic structural diagram of the temperature measurement unit and the calculation and processing unit according to an embodiment of the present application. Combining Figure 6A and Figure 6B , the temperature measurement unit in this embodiment includes a resistor R5 and a resistor R6 connected in series, and a capacitor C2. The capacitor C2 is connected in parallel with the resistor R6. The other ends of the resistor R5 and the resistor R6 are respectively connected to port 8 and port 14 of the calculation and processing unit.

[0089] The temperature measurement unit can be powered by an external power supply or an internal power supply. In this embodiment, it is powered by Figure 6A the chip U1 in [description]. The chip U1 supplies power to the bridge unit through the temperature measurement unit. The temperature measurement unit is used for temperature signal acquisition, and the calculation and processing unit processes the acquired temperature signal to perform temperature compensation on the differential voltage and outputs the processed true pressure value through the Out port. The resistor R6 in this embodiment is an NTC resistor.

[0090] In this embodiment, the temperature can be sensed through an external NTC to measure the relative temperature of the environment, so that the temperature signal can be acquired more accurately.

[0091] This embodiment stores in the storage unit the compensation gain (sensitivity) for the sensing unit, compensation zero error, temperature coefficient, temperature or coefficient of the zero point, quadratic term coefficient for calibration, etc. Thus, when the calculation and processing unit performs calculations, the correct pressure value can be calculated based on the above compensation coefficients, thereby improving the measurement accuracy.

[0092] In addition, the power supply for the bridge unit in the embodiment of the present application can adopt a continuous power supply method. Of course, in some other embodiments, an intermittent power supply method can also be adopted. The display unit can be selected from a liquid crystal display screen, an LED, etc.

[0093] Embodiment 5

[0094] According to an embodiment of the present application, a sensing circuit for temperature measurement using a bridge is also provided. Figure 7 is a schematic structural diagram of the sensing circuit for temperature measurement using a bridge according to an embodiment of the present application. Figure 7 The sensing circuit in [description] and Figure 3The difference lies in including a temperature measurement unit, and accordingly, the functions of the bridge unit and the calculation and processing unit in this embodiment are also different from those in Embodiments 3 and 4. Therefore, this embodiment will focus on describing the differences between the bridge unit and the calculation and processing unit and those in Embodiments 3 and 4, and the other parts will not be elaborated further.

[0095] In this embodiment, the bridge unit forms a Wheatstone bridge, where the differential voltage of the Wheatstone bridge is used to indicate the pressure near the Wheatstone bridge, and the current of the Wheatstone bridge is used to indicate the temperature near the sensing unit; a calculation and processing unit, connected to the bridge unit, is configured to determine the temperature based on the magnitude of the current, calibrate the temperature, and perform temperature compensation on the differential voltage based on the calibrated temperature to obtain a compensated pressure signal.

[0096] In some examples, the calculation and processing unit is further configured to: based on the initial sensitivity gain Gain of the bridge at unit temperature C 、the compensation gain Gain of the temperature measurement result T 、the zero-point error Offset of the temperature measurement compensation T and the offset compensation T of the bridge temperature shift to calibrate the temperature to obtain the calibrated temperature.

[0097] In some examples, the bridge unit includes: a sensing unit, including two variable resistance elements connected in parallel, for detecting the pressure near the piezoresistive sensor and outputting a pressure signal; a fixed resistance unit, including two fixed resistors connected in parallel, and the two fixed resistors are respectively connected in series with the two variable resistance elements to form the Wheatstone bridge; wherein, the differential voltage is the voltage between two connection points formed by respectively connecting the two fixed resistors in series with the two variable resistance elements; the current is the current in the path between the Wheatstone power supply and the ground.

[0098] In some examples, the calculation and processing unit is further configured to: convert the current of the Wheatstone bridge into temperature based on the correspondence relationship between the historical temperature and the historical current of the bridge unit obtained in advance.

[0099] In some examples, the calculation and processing unit is further configured to: perform zero-point offset compensation, linear compensation, and quadratic temperature compensation on the differential voltage based on the bridge influence coefficient of pressure, the sensitivity influence coefficient of temperature, the zero-offset influence coefficient, the linearity influence coefficient of pressure, and the calibrated temperature, where the bridge influence coefficient of pressure, the sensitivity influence coefficient of temperature, the zero-offset influence coefficient, and the linearity influence coefficient of pressure are obtained by calibrating the piezoresistive sensor at known temperatures and pressures.

[0100] In some examples, the influence coefficient of pressure on the bridge includes at least one of the following: the initial sensitivity gain Gain of the bridge unit under unit pressure A ; the influence coefficient of temperature on sensitivity includes at least one of the following: the temperature coefficient TC of the sensitivity of the bridge unit gain ; the quadratic temperature coefficient SOT of the sensitivity of the bridge unit tcg ; the influence coefficient of zero offset includes at least one of the following: the compensation B of the bridge offset generated after calibration of the piezoresistive sensor shift ; the compensation zero error Offset of the original measurement reading of the bridge unit B ; the temperature coefficient TC for the zero point offst ; the quadratic temperature correction coefficient SOT of tco ; the influence coefficient on pressure linearity includes: the quadratic coefficient SOT for non-linear correction of bridge readings B .

[0101] In this example, temperature is measured through the bridge current. For example, the temperature is measured based on the magnitude of the current of the entire Wheatstone bridge. Temperature has a linear relationship with the magnitude of the current. Therefore, temperature and current magnitude can be recorded and stored simultaneously during calibration. During actual use, the magnitude of the differential voltage signal and the current magnitude are measured simultaneously, and the temperature is determined based on the current magnitude and compensated. At the same time, the actual value of the temperature near the sensor can be output by the processing unit. This embodiment does not require an additional temperature measurement unit, which can save the space of the sensing circuit and also save costs.

[0102] Specifically, as the temperature rises, the variable resistances Rp1 and Rp2 of the bridge unit will basically increase or decrease linearly, and the current passing through the circuit (Wheatstone bridge powered by constant voltage) will decrease or increase. During calibration, the magnitude of the loop current is recorded based on the temperature at which the piezoresistive sensor is located. In this way, during use, the real-time temperature can be judged according to the magnitude of the current.

[0103] In this embodiment, after obtaining the current of the Wheatstone bridge and converting the current into temperature, the calculation and processing unit also calibrates the temperature. In this way, the accuracy of the detected temperature can be improved.

[0104] In some examples, the calibration formula for temperature can adopt the following formula:

[0105] T tmp = Gain T (Gain C ·K2·T + Offset T ) + 1

[0106] T = (Ttmp ·(1 + T tmp ·SOT T )) + T shift

[0107] Wherein, Gain C is the initial sensitivity gain of the bridge under unit temperature; P is the magnitude of the pressure; K2 is the quantization level processing coefficient of the analog-to-digital conversion; Gain T is the compensation gain for the temperature measurement result, Offset T is the zero error compensation for the temperature measurement; SOT T is the correction coefficient for the non-linear quadratic term of temperature; T tmp is the intermediate calculation result of temperature correction; T shift is the offset compensation for the bridge temperature; T is the corrected temperature reading.

[0108] After the calculation and processing unit calculates the corrected temperature T, it substitutes T into formula (3)(4) or formula (5)(6) in Embodiment 3 to further perform temperature compensation, linear compensation, and / or zero-offset compensation on the pressure signal. These compensation methods are the same as those in Embodiment 3, so they will not be elaborated here.

[0109] In this embodiment, the bridge unit measures the magnitudes of the differential voltage signal and the current simultaneously, determines the ambient temperature based on the magnitude of the current, calibrates the obtained temperature, and then compensates the pressure signal corresponding to the differential voltage using the calibrated temperature. In this way, the actual value of the temperature near the piezoresistive sensor can be obtained without the need for an additional temperature measurement unit, and the space of the sensing circuit and the piezoresistive sensor is saved, and the cost of the piezoresistive sensor and the sensing circuit is also reduced.

[0110] Embodiment 6

[0111] Figure 8A is a schematic structural diagram of the sensing circuit according to an embodiment of the present application. This sensing circuit is similar to the Figure 2 schematic structural diagram of the sensing circuit shown, and includes a temperature measurement unit, a bridge unit, a spike interference suppression unit, a filtering unit, a calculation and processing unit, a circuit protection unit, an alarm and interruption unit, and a storage unit. Among them, the bridge unit includes a sensing unit 142 and a fixed resistor unit.

[0112] As Figure 8A shown, the sensing unit 142 of the bridge unit and the temperature measurement unit 12 are arranged at the distal end of the wire 102 and are used to extend into the body of the monitored object to detect the pressure and temperature inside the monitored object. The sensing unit 142 can also be referred to as a piezoresistive sensor.

[0113] The fixed resistance unit, spike interference suppression unit, filtering unit, calculation and processing unit, circuit protection unit, alarm and interruption unit, and storage unit of the bridge unit are integrated on the sensing circuit board 104 at the proximal end of the wire 102.

[0114] Among them, the proximal end is the end of the wire 102 close to the object to be monitored, and the distal end is the end of the wire 102 far from the object to be monitored.

[0115] The structure of the sensing circuit is the same as the circuit structure and function of the sensing circuits in the above-mentioned Embodiments 2, 3, and 4. It uses the temperature detection unit 12 to detect the temperature of the internal environment of the object to be monitored. Therefore, it will not be elaborated here.

[0116] Embodiment 7

[0117] Figure 8B It is a schematic structural diagram of another sensing circuit according to the embodiment of the present application. This sensing circuit corresponds to the circuit structure of the sensing circuit in the above-mentioned Embodiment 5 and uses a bridge unit instead of a temperature detection unit to detect the pressure of the internal environment of the object to be monitored.

[0118] The sensing circuit includes a bridge unit, a spike interference suppression unit, a filtering unit, a calculation and processing unit, a circuit protection unit, an alarm and interruption unit, and a storage unit. Among them, the bridge unit includes a sensing unit and a fixed resistance unit.

[0119] As Figure 8B shown, the sensing unit 142 of the bridge unit is arranged at the distal end of the wire 102 and is used to extend into the body of the object to be monitored to detect the pressure and temperature inside the body of the object to be monitored.

[0120] The fixed resistance unit, spike interference suppression unit, filtering unit, calculation and processing unit, circuit protection unit, alarm and interruption unit, and storage unit of the bridge unit are integrated on the sensing circuit board 104 at the proximal end of the wire 102.

[0121] The structure of the sensing circuit is the same as the circuit structure and function of the sensing circuit in the above-mentioned Embodiment 5. It uses a bridge unit to detect the pressure and temperature of the internal environment of the object to be monitored. Therefore, it will not be elaborated here.

[0122] Embodiment 8

[0123] According to the embodiment of the present application, a medical catheter is also provided. As Figure 8C shown, the medical catheter includes a catheter body 106 and a sensing circuit as shown in Figure 8A or Figure 8B shown.

[0124] Among them, the wire 102 is disposed within the catheter body 106, and the sensing unit 142 is disposed within the end portion at the distal end of the wire 102. Except for the sensing unit 142, other units of the sensing circuit are integrated on the sensing chip. Among them, the sensing circuit board 104 is located at the proximal end of the catheter body 106.

[0125] In other examples, it may also be that the sensing unit 142 and the temperature measurement unit are disposed within the end portion at the distal end of the wire 102. Except for the sensing unit 142, other units of the sensing circuit are integrated on the sensing circuit board.

[0126] The structure of the sensing circuit is the same as that of the sensing circuit in the above embodiment. Therefore, it will not be elaborated here.

[0127] Embodiment 9

[0128] According to an embodiment of the present application, a medical monitoring system is further provided. Figure 9 It is a schematic structural diagram of a medical monitoring system according to an embodiment of the present application. As Figure 9 shown, the medical monitoring system includes a medical catheter 106 and a monitoring device 200. Among them, a sensing unit 142 is disposed at the end portion at the distal end of the medical catheter 106, and a sensing circuit board 104 is disposed at the end portion at the proximal end. Other components of the sensing circuit except the sensing unit 142 are integrated on the sensing circuit board 104. The sensing unit 142 and the sensing circuit board 104 are connected by a wire 102.

[0129] In other embodiments, the end portion at the distal end of the medical catheter 106 may be provided with not only the sensing unit 142 but also a temperature measurement unit. The end portion at the proximal end is provided with a sensing circuit board 104. Other components of the sensing circuit except the sensing unit 142 are integrated on the sensing circuit board 104. The sensing unit 142 and the temperature measurement unit are connected to the sensing circuit board 104 by a wire 102.

[0130] The structure and function of the sensing circuit are similar to those of the sensing circuit in the above embodiment. It will not be elaborated here.

[0131] Embodiment 10

[0132] According to an embodiment of the present application, a method for compensating a pressure signal is further provided. Figure 10 It is a flowchart of a method for compensating a pressure signal according to an embodiment of the present application. As Figure 10 shown, the method includes the following steps:

[0133] Step S900, obtaining a calibration coefficient and a compensation relationship through calibration.

[0134] Under known different pressure and temperature environments, sense the differential voltage signal output by the sensing Wheatstone bridge unit, and calibrate the piezoresistive sensor to obtain calibration coefficients. If it is the case of measuring temperature with a bridge, it is necessary to detect the current signal while detecting the differential voltage signal, and obtain the calibration coefficients by calibrating the differential voltage signal and the current signal. These calibration coefficients can include, for example, the compensation gain (sensitivity) of the original measurement readings of the bridge unit, the compensation zero error of the original measurement readings of the bridge unit, the temperature coefficient of the sensitivity of the bridge unit, the temperature coefficient of the zero point of the bridge unit, and other data.

[0135] For example, at the reference temperature, by measuring the output value changes of the piezoresistive sensor at zero pressure and full pressure, the compensation gain (sensitivity) data of the original measurement readings of the bridge unit can be obtained; by measuring the zero output of the bridge unit, the compensation zero error of the original measurement readings of the bridge unit can be obtained; by measuring the values of zero pressure and full pressure at different temperatures, the temperature coefficient of the sensitivity of the bridge unit can be obtained, etc.

[0136] Based on these coefficients, establish compensation relationships, such as the compensation relationships shown in formulas (3) to (5).

[0137] Step S902, detect the temperature signal and the pressure signal.

[0138] Use the temperature measurement unit to detect the temperature, or use the bridge unit to detect the temperature. While obtaining the temperature signal, detect the differential voltage of the Wheatstone bridge of the bridge unit, and this differential voltage characterizes the pressure of the environment where the piezoresistive sensor is located.

[0139] Step S904, based on the compensation relationship, use the temperature signal to compensate the pressure signal.

[0140] Use the compensation relationship to compensate the differential voltage value output by the bridge unit to obtain the true pressure value.

[0141] The specific compensation method is the same as the compensation method in the sensing circuit in the above embodiment. For example, the formula for parabolic correction of the sensor bridge can be used for compensation, or another correction formula based on the S-shaped curve of the piezoresistive sensor bridge can be used, which will not be elaborated here.

[0142] In this embodiment, the sensing unit senses the ambient pressure and the temperature measurement unit or the bridge unit detects the ambient temperature. Then, the pressure signal sensed by the bridge unit is filtered and then sent into the processing and calculation unit. In the processing and calculation unit, based on the compensation relationship in the storage unit and the measured temperature, the true ambient pressure value is calculated and finally output to the display unit for display.

[0143] The method in this embodiment can achieve all the functions implemented by the sensing circuit in the above embodiment. Therefore, it will not be elaborated here.

[0144] Figure 11 It is a schematic diagram of the effects before and after calibration of pressure using temperature. Among them, the horizontal axis represents the magnitude of pressure, the left vertical axis represents the output of the pressure value without temperature calibration, and the right vertical axis represents the output of the pressure value after temperature calibration.

[0145] It should be noted that for the foregoing method embodiments, for the sake of simple description, they are all expressed as a series of action combinations. However, those skilled in the art should know that this application is not limited by the described action sequence, because according to this application, certain steps can be performed in other sequences or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily essential to this application.

[0146] Through the description of the above embodiments, those skilled in the art can clearly understand that the method according to the above embodiments can be implemented by means of software plus a necessary general hardware platform. Of course, it can also be implemented by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of this application, in essence, or the part that makes a contribution to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk), and includes several instructions for causing a terminal device (which can be a mobile phone, computer, server, or network device, etc.) to execute the methods described in various embodiments of this application.

[0147] In the above embodiments of this application, the descriptions of each embodiment have their own focuses. For the parts not detailed in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0148] In the several embodiments provided by this application, it should be understood that the disclosed client can be implemented in other ways. Among them, the device embodiments described above are only illustrative. For example, the division of the units is only a logical function division. In actual implementation, there can be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed coupling or direct coupling or communication connection to each other can be through some interfaces. The indirect coupling or communication connection of units or modules can be in an electrical or other form.

[0149] The unit described as a separation component may or may not be physically separated. The component shown as a unit may or may not be a physical unit, that is, it may be located in one place or may be distributed across multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0150] In addition, each functional unit in various embodiments of the present application may be integrated in a processing unit, may also exist physically separately for each unit, or two or more units may be integrated in one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of a software functional unit.

[0151] The above are only the preferred embodiments of the present application. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present application, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present application.

Claims

1. A piezoresistive sensor sensing circuit, characterized in that, Comprising: A temperature measurement unit, including a diode or an NTC resistor, for measuring the temperature near the piezoresistive sensor through the diode or the NTC resistor to obtain a temperature signal; A bridge unit, for detecting a pressure signal near the piezoresistive sensor and outputting a differential voltage based on the pressure signal; A calculation and processing unit, connected to the bridge unit and the temperature measurement unit, for performing temperature compensation on the differential voltage based on the temperature signal to obtain the compensated pressure signal; Wherein, the calculation and processing unit is further configured to: perform zero-offset compensation, linear compensation, and the temperature compensation on the differential voltage based on the bridge influence coefficient of pressure, the sensitivity influence coefficient of temperature, the zero-offset influence coefficient, and the linearity influence coefficient of pressure on pressure, wherein the bridge influence coefficient of pressure, the sensitivity influence coefficient of temperature, the zero-offset influence coefficient, and the linearity influence coefficient of pressure on pressure are obtained by calibrating the piezoresistive sensor at known temperatures and pressures; Wherein, the calculation and processing unit is further configured to compensate the differential voltage using the following formula: B tmp = Gain B ·(1 + TC gain ·ΔT + SOT tcg ·ΔT 2 )·(K·U·Gain A - Offset B + TC offset ·ΔT + SOT tco ·ΔT 2 ) B = (B tmp ·(1 + |B tmp |·SOT B )) + 1) + B shift Among them, Gain A is the initial sensitivity gain of the Wheatstone bridge under unit pressure; U is the differential voltage small; K is the quantization level processing coefficient of the analog-to-digital conversion; B is the reading of the Wheatstone bridge unit of the calibrated piezoresistive sensor; B tmp is the intermediate calculation result of the reading of the Wheatstone bridge unit of the piezoresistive sensor; B shift is the compensation for the offset of the Wheatstone bridge unit generated after calibration or encapsulation of the piezoresistive sensor; Gain B is the compensation gain for the original measurement reading of the Wheatstone bridge unit of the piezoresistive sensor; Offset B is the compensation zero error for the original measurement reading of the Wheatstone bridge unit of the piezoresistive sensor; TC gain is the temperature coefficient of the sensitivity of the Wheatstone bridge unit of the piezoresistive sensor; TC offst is the temperature coefficient of the zero point of the Wheatstone bridge unit of the piezoresistive sensor; SOT tcg is for TC gain temperature correction quadratic term coefficient; SOT tco is for TC offst temperature correction quadratic term coefficient; SOT B is the quadratic term coefficient for non-linear correction of the Wheatstone bridge reading, T represents the set base temperature, and ΔT represents the difference between the actual temperature and the base temperature.

2. The sensing circuit according to claim 1, wherein, The bridge unit includes: A sensing unit, including a variable resistance element, for detecting the pressure near the piezoresistive sensor and outputting a pressure signal; A fixed resistance unit, connected to the sensing unit, for forming a Wheatstone bridge with the variable resistance element to collect the differential voltage.

3. The sensing circuit according to claim 1, wherein The calculation and processing unit outputs the compensated pressure signal as a proportional voltage, or outputs it digitally in SENT protocol, or outputs it in PWM, or outputs it in I2C; The calculation and processing unit is further configured to output the output compensated pressure signal and display it on a display unit.

4. The sensing circuit according to claim 3, wherein The calculation and processing unit further includes an alarm and interruption unit, for alarming in the case where the compensated pressure signal exceeds a pressure threshold or the compensated temperature signal exceeds a temperature threshold, and performing short-circuit power-off protection on the sensing circuit.

5. The sensing circuit according to claim 2, wherein The sensing circuit further includes a circuit protection unit, the circuit protection unit is connected to the sensing unit and the calculation and processing unit, for performing electrostatic discharge protection on the sensing unit and the calculation and processing unit.

6. The sensing circuit according to claim 2, wherein The sensing circuit further includes: A spike interference suppression unit, connected between the sensing unit and the fixed resistance unit, for filtering spike interference in the pressure signal; and / or A filtering unit, connected between the bridge unit and the calculation and processing unit, for filtering noise in the differential voltage.

7. The sensing circuit according to claim 6, wherein The variable resistance element of the sensing unit includes a first variable resistor RP1 and a second variable resistor RP2; The spike interference suppression unit includes a first magnetic bead FB1, a second magnetic bead FB2, and a third magnetic bead FB3, wherein one end of the first magnetic bead FB1 is connected to the calculation and processing unit via a first resistor R1, and the other end is respectively connected to one ends of the first variable resistor RP1 and the second variable resistor RP2; The bridge unit includes a tenth resistor R10 and an eleventh resistor R11. One end of the tenth resistor R10 is connected in series with one end of the eleventh resistor R11. The other end of the tenth resistor R10 is connected to the other end of the first variable resistor RP1 via the second bead FB2. The other end of the eleventh resistor R11 is connected to the other end of the second variable resistor RP2 via the third bead FB3.

8. The sensing circuit according to claim 6, wherein The filtering unit includes a fourth resistor R4, a ninth resistor R9, a third capacitor C3, a fourth capacitor C4, and a fifth capacitor C5. One end of the fourth resistor R4 is connected to the calculation and processing unit, and the other end is connected to the bridge unit. One end of the ninth resistor R9 is connected to the calculation and processing unit, and the other end is connected to the bridge unit. One end of the fourth capacitor C4 is connected to the fourth resistor R4 and the calculation and processing unit, and the other end is grounded. One end of the fifth capacitor C5 is connected to the ninth resistor R9 and the calculation and processing unit, and the other end is grounded. One end of the third capacitor C3 is connected to the fourth capacitor C4, and the other end is connected to the fifth capacitor C5.

9. The sensing circuit according to claim 1, wherein The temperature measurement unit includes: A diode D1, with both ends of the diode D1 connected to both ends of the calculation and processing unit; or A fifth resistor R5, a sixth resistor R6, and a second capacitor C2. Wherein, one end of the fifth resistor R5 is connected to the calculation and processing unit, and the other end is respectively connected to one end of the sixth resistor R6 and one end of the second capacitor C2. The other end of the second capacitor C2 is connected to the other end of the sixth resistor R6. The other end of the sixth resistor R6 is connected to the calculation and processing unit. Wherein, the sixth resistor R6 is the NTC resistor.

10. The sensing circuit according to claim 1, wherein The second port of the calculation and processing unit is grounded, the first port is connected to the power supply, the fourth port is connected to one end of the bridge unit through the fourth resistor R4 and the third resistor R3, the sixth port is connected to the other end of the bridge unit through the ninth resistor R9 and the eighth resistor R8, and the fifth port is connected to the power supply port of the bridge unit through the second resistor R2 and the first resistor R1.

11. A medical catheter for insertion into the body of a subject to be monitored, characterized in that, Includes: A catheter body; The sensing circuit according to any one of claims 1 to 10, wherein the sensing unit of the sensing circuit is disposed at one end of the catheter body, and the remaining components of the sensing circuit except the sensing unit are disposed at the other end of the catheter body. The sensing unit is connected to the remaining components through a wire.

12. A medical monitoring system, characterized in that, Includes: The medical catheter according to claim 11; A monitoring device for monitoring and displaying the data detected by the sensing circuit when the medical catheter is inserted into the body of the monitored object.

13. A method for compensating the pressure signal of a piezoresistive sensor, characterized in that, Includes: Measuring the temperature near the piezoresistive sensor through the temperature measurement unit of the piezoresistive sensor to obtain a temperature signal; Detecting the pressure signal near the piezoresistive sensor through the bridge unit of the piezoresistive sensor and outputting a differential voltage based on the pressure signal; Performing temperature compensation on the differential voltage based on the temperature signal to obtain the compensated pressure signal; Wherein, the compensation method is executed by the sensing circuit according to any one of claims 1 to 10.

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