WO2019134552A1 - 一种弹性电阻应变片及其制备方法和应用 - Google Patents

一种弹性电阻应变片及其制备方法和应用 Download PDF

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Publication number
WO2019134552A1
WO2019134552A1 PCT/CN2018/123167 CN2018123167W WO2019134552A1 WO 2019134552 A1 WO2019134552 A1 WO 2019134552A1 CN 2018123167 W CN2018123167 W CN 2018123167W WO 2019134552 A1 WO2019134552 A1 WO 2019134552A1
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Prior art keywords
resistance
strain gauge
elastic
composite material
polymer layer
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PCT/CN2018/123167
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English (en)
French (fr)
Inventor
杨泽宇
郭仪
杨柏超
高莉
廖方骐
刘奎生
Original Assignee
成都柔电云科科技有限公司
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Priority claimed from CN201810016225.4A external-priority patent/CN108036714A/zh
Priority claimed from CN201810015675.1A external-priority patent/CN108036804B/zh
Priority claimed from CN201810051942.0A external-priority patent/CN107951490A/zh
Application filed by 成都柔电云科科技有限公司 filed Critical 成都柔电云科科技有限公司
Publication of WO2019134552A1 publication Critical patent/WO2019134552A1/zh

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/103—Detecting, measuring or recording devices for testing the shape, pattern, colour, size or movement of the body or parts thereof, for diagnostic purposes
    • A61B5/11—Measuring movement of the entire body or parts thereof, e.g. head or hand tremor, mobility of a limb
    • A61B5/113—Measuring movement of the entire body or parts thereof, e.g. head or hand tremor, mobility of a limb occurring during breathing
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00—Measuring force or stress, in general
    • G01L1/18—Measuring force or stress, in general using properties of piezo-resistive materials, i.e. materials of which the ohmic resistance varies according to changes in magnitude or direction of force applied to the material

Definitions

  • the name of the original institution is: State Intellectual Property Office of the People's Republic of China, the first application date is: January 08, 2018, the first application number is: 201810016225.4;
  • the name of the original accepting institution is: State Intellectual Property Office of the People's Republic of China, the first filing date is: January 19, 2018, the first application number is: 201810051942.0.
  • the invention relates to the technical field of resistance strain sensing measurement, in particular to an elastic resistance strain gauge and a preparation method and application thereof.
  • Resistance strain gauges are a common type of sensing element. When the physical quantities such as tensile force, pressure, torque, displacement, acceleration, temperature, etc., are changed by the resistance strain gauge, the corresponding change of the electrical resistance is also obtained. By measuring and outputting the electrical resistance, the corresponding physical quantity measurement value can be obtained. .
  • Resistance strain gauges commonly found in the prior art are metal strain gauges and semiconductor strain gauges.
  • the metal strain gauge is made of a constantan wire or a nickel-chromium wire, or is formed by etching a thin metal foil into a grid and sandwiching the two insulating sheets, and then connecting the silver plated copper wire to the strain gauge wire grid. As the resistance piece lead, the magnitude of the stress is detected by the change in the resistance value caused by the deformation of the wire.
  • the semiconductor strain gauge is a sensitive component made by utilizing the piezoresistive effect of single crystal silicon, and the physical quantity such as pressure and tensile force of the strain gauge is detected by deformation of the semiconductor material to cause a change in resistivity.
  • metal strain gauges are widely used in the weighing field, but have the disadvantages of low sensitivity and large mechanical hysteresis.
  • the accuracy and sensitivity of the semiconductor strain gauge are higher than that of the metal strain gauge. It can be widely used in the measurement of mechanical quantities of aircraft, vehicles, ships, etc., but it has the disadvantages of poor temperature stability, large nonlinear error under large stress, and low mechanical strength. .
  • the Chinese Patent Application Publication No. CN102506693A discloses a graphene-based strain measurement or motion sensing device that incorporates one or more layers of graphene film on a flexible insulating substrate to detect stress changes.
  • the scheme combines the graphene film layer on the substrate by attaching, and the difference between the tensile property and the stress variation of the flexible insulating substrate and the graphene film layer is obvious, and the accuracy of the measurement result is not only caused by the difference of the shape variables. And the measurement range of the entire device is limited by the graphene layer with a smaller deformation.
  • the Chinese Patent Application Publication No. CN104538088A discloses a high tensile conductive elastomer, although it incorporates an aromatic group by surface modification techniques on the surface of the elastomer to closely bond the surface of the elastomer to the graphene conductive layer.
  • the close-knit combination does not fundamentally eliminate the difference between the tensile properties and the stress changes of the two, nor can it expand the range of the deformation of the conductive layer.
  • due to the instability of the graphene conductive layer and the small range of shape variables the above solutions are greatly affected by the application environment temperature, strain gauge aging, etc., and there are technical problems such as drift of measurement results and large errors.
  • At least one of the objects of the present invention is to provide an elastic resistance strain gauge and a preparation method and application thereof, which are capable of overcoming the problems of the prior art described above, and the elastic resistance strain gauge has high tensile property and stress variation. It has strong adsorption and can reduce drift and error while increasing the resilience of the strain gauge itself. It is less affected by temperature and has higher stability. It can be used as the basic material of elastic stretchable electronic devices. Applied in medical and smart wear.
  • the technical solution adopted by the present invention includes the following aspects.
  • An elastic resistance strain gauge comprising: a non-conductive polymer layer and a conductive polymer layer, wherein the conductive polymer layer is located on a surface of the non-conductive polymer layer; wherein the non-conductive polymer layer is high by the first elasticity
  • the molecular composite material is made of; the conductive polymer layer is made of a second elastic polymer composite material; and the second elastic polymer composite material is made of the first elastic polymer composite material and the conductive filler.
  • a method for preparing an elastic resistance strain gauge comprising: preparing a liquid first elastic polymer composite material; injecting a liquid first elastic polymer composite material into a first mold, heating and solidifying the first elastic polymer a composite material to form a non-conductive polymer layer; a liquid second elastic polymer composite material; a liquid second elastic polymer composite material flat on the cured non-conductive polymer layer, heated, The second elastic polymer composite material is cured to form a conductive polymer layer and solidified on the surface of the non-conductive polymer layer.
  • An apparatus for output adjustment of a resistance strain gauge comprising: a resistance strain gauge connected in sequence, a measurement circuit, an amplifier, an analog to digital conversion circuit, a microprocessor, and a DC power supply for supplying power to the device; wherein
  • the measuring circuit has a first resistor connected in parallel with the lead of the resistance strain gauge, and a second resistor connected in series with the first resistor, the resistance of the first resistor is smaller than the minimum value of the equivalent resistance of the strain gauge to make the measuring circuit according to the resistance
  • the resistance value of the strain gauge outputs a corresponding voltage signal;
  • the amplifier is for amplifying the amplitude of the voltage signal output by the measuring circuit; and the analog to digital conversion circuit is configured to convert the output signal of the amplifier into a digital signal;
  • the micro processing The device is configured to calculate the resistance value of the equivalent resistance of the resistance strain gauge according to the resistance values of the first resistor and the second resistor and the voltage value of the DC power source, and generate a measurement corresponding to the resistance strain gauge variable according
  • a portable respiratory monitoring system based on an elastic resistance strain gauge comprising the device; wherein the elastic resistance strain gauge is disposed as an elastic structure directly adhered to human skin, and stretched as the diaphragm contractes, As the diaphragm muscle relaxes and rebounds, the resistance value of the elastic resistance strain gauge changes accordingly; the microprocessor is used to calculate the elastic resistance strain according to the resistance value of the fixed resistance resistor and the resistance adjustable resistor and the voltage value of the DC power source.
  • the resistance value of the equivalent resistance of the sheet is generated according to the resistance value of the equivalent resistance, and the measurement data corresponding to the elastic strain gauge variable is generated, and the breathing is generated according to the peak value and the changing frequency of the resistance value of the elastic resistance strain gauge in the measurement data. Breath curve data for depth and frequency.
  • the present invention has at least the following beneficial effects:
  • the tensile properties and the stress variation of the conductive polymer layer and the non-conductive polymer layer are high, which increases the resilience of the strain gauge itself and reduces drift.
  • the non-conductive polymer layer is made of elastic polymer composite material, which can detect the deformation variable with large sensitive size relative to the strain gauge, and the error is small; and the polymer composite material used is affected by temperature.
  • the drift and error of the signal, and the resistance of the resistance strain gauge can be changed after the resistance strain gauge is repeatedly stretched and aged, and the resistance of the resistance strain gauge is changed to maintain the stability of the measurement result. Avoid the influence of aging of the strain gauge; further convert the resistance value data of the elastic strain gauge to reflect the breath.
  • the breathing curve data of depth and frequency can display the breathing state of the monitored object intuitively and accurately, and the measurement data can be further analyzed by the host computer. The frequency or depth in the breathing curve data exceeds the preset threshold range. The corresponding alarm is triggered to alert the user.
  • FIG. 1 is a cross-sectional view of an elastic resistance strain gauge according to an embodiment of the present invention.
  • FIG. 2 is an elastic resistance strain gauge in which a non-conductive polymer layer and a conductive polymer layer are both provided in a circular shape according to an embodiment of the present invention.
  • FIG. 3 is an elastic resistance strain gauge according to an embodiment of the present invention, wherein a non-conductive polymer layer is disposed in a rectangular shape, and the conductive polymer layers are each disposed in an elongated shape.
  • FIG. 4 is an elastic resistance strain gauge having a conductive polymer layer disposed in a U structure according to an embodiment of the present invention.
  • Fig. 5 is a view showing an elastic resistance strain gauge having a conductive polymer layer provided in a plurality of U-shaped connected structures according to an embodiment of the present invention.
  • Fig. 6 is a view showing an elastic resistance strain gauge having a conductive polymer layer provided with a wire connection point according to an embodiment of the present invention.
  • FIG. 7 is a flow chart of a method of preparing an elastic resistance strain gauge according to an embodiment of the present invention.
  • FIG. 8 is a schematic structural diagram of an apparatus for output adjustment according to an embodiment of the present invention.
  • FIG. 9 is a schematic diagram of a reference connection circuit of an amplifier in accordance with an embodiment of the present invention.
  • FIG. 10 is a schematic structural diagram of a measurement circuit according to an embodiment of the present invention.
  • FIG. 11 is a schematic diagram showing changes in amplitude of a voltage signal outputted by one of the prior art.
  • Figure 12 is a diagram showing changes in amplitude of a voltage signal at the output of a measuring circuit in accordance with an embodiment of the present invention.
  • FIG. 13 is a schematic structural diagram of a measuring circuit according to another embodiment of the present invention.
  • Figure 14 is a block diagram showing the structure of a measuring circuit in accordance with still another embodiment of the present invention.
  • 15 is a schematic view showing the sticking of an elastic resistance strain gauge in a portable respiratory monitoring system during inhalation according to an embodiment of the present invention.
  • 16 is a schematic view showing the sticking of an elastic resistance strain gauge in a breath breathing monitoring system according to an embodiment of the present invention.
  • FIG. 17 is a block diagram showing the structure of a portable respiratory monitoring system in accordance with an embodiment of the present invention.
  • the elastic resistance strain gauge of this embodiment includes a non-conductive polymer layer and a conductive polymer layer.
  • the non-conductive polymer layer is made of a first elastic polymer composite material;
  • the conductive polymer layer is made of a second elastic polymer composite material; and the second elastic polymer composite material is first Made of elastic polymer composite material and conductive filler;
  • the first elastic polymer composite material is a polymer composite material capable of forming a stable surface after curing and having a draw ratio of 100% to 500%; and the conductive polymer layer is cured on the surface of the non-conductive polymer layer.
  • the non-conductive polymer layer serves as a base of the conductive polymer layer, and the two are closely combined, and the tensile property and the stress change are highly consistent; after the stress loading of the strain gauge is completed, the conductive polymer layer itself has In addition to the resilience, the non-conductive polymer layer will additionally add a resilience to the conductive polymer layer, so that the strain gauge can return to its original state at the fastest speed, reducing the drift and error of the strain gauge.
  • silica gel, rubber, or the like can be selected as the first elastic polymer composite material according to different measurement targets and ranges.
  • the stretching ratio can reach 500% (for example, the length of the material in the stretching direction and the length when the material is not stretched) Ratio); when using rubber, the draw ratio can reach 200% to 300%.
  • the strain gauges made by selecting different polymer composite materials have different sensitivity and linearity.
  • the second elastic polymer composite material is made of a first elastic polymer composite material having a mass fraction of 70% to 99.5% and a conductive filler having a mass fraction of 0.5% to 30%.
  • the conductive filler may be a carbon-based conductive filler or a metal-based conductive filler; the carbon-based conductive filler may include carbon black, acetylene black, graphite, carbon fiber, etc.; the metal-based conductive filler is gold powder, silver powder, copper powder, aluminum powder, nickel Powder and so on.
  • carbon black having a mass fraction of 10% to 18% may be selected as the conductive filler, and silica gel having a mass fraction of 82% to 90% is used as the first elastic polymer composite material to obtain the first Two elastic polymer composite materials.
  • the static resistance, detection range, sensitivity and linearity of the strain gauges are also different.
  • Table 1 below shows a plurality of different mass fractions of carbon black used as a conductive filler in accordance with a preferred embodiment of the present invention, and a corresponding mass fraction of silica gel is used as the first elastic polymer composite material.
  • the non-conductive polymer layer and the conductive polymer layer of the elastic strain gauge according to the embodiment shown in FIG. 2 and FIG. 3 may be provided in a shape of a circle, a rectangle, a square, an elongated strip or the like.
  • the non-conductive polymer layer may be disposed along the elongated shape of the muscle texture and the conductive polymer layer may be disposed in the non-conductive polymer layer.
  • the upper edge extends over the length range to increase the range of stress variation detected; and the wire is led through the end or edge of the conductive polymer layer, and the resistance change of the conductive polymer layer is measured by a resistance metering device connected to the wire, thereby obtaining The value of the stress change.
  • the conductive polymer layer may have a thickness of 1 um to 100 um, and the non-conductive polymer layer may have a thickness of 0.3 mm to 2 mm.
  • the thinner strain gauge has the advantages of light weight and high elasticity, and can be applied to scenes with high stability, drift and error requirements for medical, intelligent wear, aerospace and other corresponding variograms.
  • the elastic resistance strain gauge provided by the present invention can be made into a ring shape and worn around the chest cavity, and the respiratory frequency and respiratory intensity data can be obtained by measuring the resistance change of the strain gauge.
  • the elastic resistance strain gauge may be directly attached to the body surface position having a larger blood vessel under it, and the heart rate data may be obtained by measuring the resistance change of the strain gauge.
  • a plurality of strain gauges can be fabricated as a joint sheath (eg, a wrist joint sheath, a knee joint sheath, a glove, etc.), and the state data of the joint can be obtained by changing the resistance values of the plurality of strain gauges. .
  • a protective layer may be disposed on the surface of the conductive polymer layer, and the protective layer is a PET film, a PU film or a first elastic high.
  • the protective layer is a PET film, a PU film or a first elastic high.
  • the conductive polymer layer of the elastic resistance strain gauge of the embodiment shown in FIG. 4 and FIG. 5 may be provided in a U shape or a structure in which a plurality of U-shaped phases are connected, so that the same contact area (usually, a non-conductive polymer layer) can be used.
  • the shape of the conductive polymer layer is increased under the contact area with the measurement target, thereby improving the sensitivity of the strain gauge detection.
  • the conductive polymer layer may be provided in a spiral shape, a hexagonal honeycomb structure or the like.
  • the width of the wire may be matched at the end of the elongated conductive polymer layer or on the edge of other shapes. Wire connection points to improve the reliability of the connection.
  • FIG. 7 is a flow chart showing a method of preparing an elastic resistance strain gauge according to an embodiment of the present invention.
  • the preparation method of this embodiment comprises the following steps:
  • Step 101 preparing a liquid first elastic polymer composite material
  • silica gel is selected as the first elastic polymer composite material, and AB two-component silica gel can be used to prepare liquid silica gel.
  • the component A zero-degree liquid silica gel and the component B curing agent may be taken, and the components A and B are thoroughly mixed to obtain a liquid silica gel.
  • the ratio of the A and B components can be set to one to one or other ratio according to the formulation requirements of the existing AB two-component silica gel.
  • Step 102 injecting a liquid first elastic polymer composite material into the first mold, heating and curing the first elastic polymer composite material to form a non-conductive polymer layer;
  • the first mold may have a shape corresponding to the non-conductive polymer layer, or may be a shape that is easy to produce (for example, a rectangle or a square), and then form a non-conductive polymer layer of a predetermined shape by a cutting step.
  • the heating temperature is usually less than 100 ° C. The smaller the heating temperature is, the longer the heating time is required.
  • the specific heating temperature and time can be selected according to the actual situation.
  • the preferred heating temperature is 90 ° C, the heating time is 30 minutes, and the curing time is greater than 15 minutes.
  • Step 103 preparing a liquid second elastic polymer composite material
  • the AB two-component silica gel can be first used to prepare a liquid silica gel having a mass fraction of 82% to 90%, and then the mass fraction is 10%. 18% carbon black is used as a conductive filler to be added to the liquid silica gel, and the mixture is uniformly stirred to thoroughly mix the carbon black and the liquid silica gel to form a liquid conductive silica gel.
  • a dispersant for example, silica, alumina
  • a mass fraction of 0.5% to 5% before stirring
  • silica alumina
  • 2% of silica may be added as A dispersant to make the conductive filler more conductive in the silica gel.
  • Step 104 The liquid second elastic polymer composite material is laid on the cured non-conductive polymer layer through the second mold, and the second elastic polymer composite material is heated and solidified to form a conductive polymer layer. Curing on the surface of the non-conductive polymer layer.
  • the second mold may have a shape corresponding to a predetermined conductive polymer layer (for example, a U shape or a plurality of U shapes) to form a conductive polymer layer of a predetermined shape.
  • a predetermined conductive polymer layer for example, a U shape or a plurality of U shapes
  • step 104 instead of using the second mold, the liquid second elastic polymer composite material may be directly laid on the cured non-conductive polymer layer to heat and solidify the second elastic polymer composite. The material is then cut to obtain the desired shape.
  • the preferred heating temperature is 90 ° C, the heating time is 30 minutes, and the curing time is greater than 15 minutes.
  • the conductive polymer layer is formed by directly curing the second elastic polymer composite material on the non-conductive polymer layer, so that the tensile properties and stress changes of the conductive polymer layer and the non-conductive polymer layer are highly uniform, and the strain gauge can be increased. Its own resilience and reduce drift and error.
  • the disclosure of the present invention A device for output adjustment of a strain gauge (including the elastic strain gauge of the foregoing embodiments and a conventional strain gauge).
  • the apparatus of this embodiment includes a resistance strain gauge, a measurement circuit, an amplifier, an amplitude modulation circuit, an analog-to-digital conversion circuit, a microprocessor, a communication interface, and a DC power supply for supplying power to the device.
  • the measuring circuit has a fixed resistance resistor connected in parallel with the lead of the resistance strain gauge, and a resistance adjustable resistor connected in series with the fixed resistance resistor for outputting a corresponding voltage signal according to the resistance value of the resistance strain gauge.
  • An amplifier for amplifying the amplitude of the voltage signal to the input range of the amplitude modulation circuit For example, AD8236, AD8634, etc., low-noise amplifiers from Analog Devices, Inc., having a bandwidth of 9.7 MHz and an input voltage noise density of 10 nV/
  • the amplifier circuit uses AD8236, and the reference connection circuit is as shown in FIG. 9.
  • VREF is the reference voltage (eg 5V)
  • C is the bypass capacitor (eg 0.1 ⁇ F).
  • the relationship between G and the gain setting resistor R G is as shown in Table 2, and the amplitude of the output voltage signal is adjusted to be within the input voltage range of the signal modulation circuit by changing the gain setting resistor R G to reduce the drift and error of the detection signal. .
  • the amplitude modulation circuit comprises a triode and an LC resonant circuit for nonlinearly frequency-converting the input voltage signal by an equal-amplitude carrier generated by the high-frequency carrier oscillator, and outputting the amplitude-modulated wave.
  • the amplitude modulation circuit is optional.
  • the amplitude of the voltage signal can be amplified to the input range of the analog to digital conversion circuit by setting the gain factor of the amplifier.
  • An analog to digital conversion circuit for converting an amplitude modulated wave into a digital signal.
  • the Motorola MC14433 chip and peripheral resistors and capacitors can be used to form an analog-to-digital conversion circuit.
  • the microprocessor is configured to calculate the resistance value of the equivalent resistance of the resistance strain gauge according to the resistance value of the fixed resistance resistance and the resistance adjustable resistance and the voltage value of the DC power source, and generate and convert according to the resistance value of the equivalent resistance Resistance strain gauge variable corresponding measurement data.
  • the microprocessor can use TI's 16-bit RISC microcontroller MSP-430F413.
  • the generated measurement data can be directly displayed through a display connected to the microprocessor (for example, an LED display screen integrated with a strain gauge), or the generated measurement data can be transmitted through a communication interface connected to the microprocessor.
  • a display connected to the microprocessor for example, an LED display screen integrated with a strain gauge
  • the generated measurement data can be transmitted through a communication interface connected to the microprocessor.
  • Other devices such as data analysis servers, to further process or store the measurement data.
  • FIG. 10 is a block diagram showing the structure of a measuring circuit according to an embodiment of the present invention.
  • the equivalent resistance of the strain gauge is expressed as Rx; the lead at one end of the strain gauge is connected to the DC power source VCC, and the other end is connected to the adjustable resistance resistor R2; one end of the resistance adjustable resistor R2 is connected in series with the strain gauge. The other end is grounded; the fixed resistance resistor R1 is connected in parallel with the lead of the resistance strain gauge; the voltage Uo across the resistance adjustable resistor R2 is output as a voltage signal to the amplifier.
  • the resistor R2 may also be set as a resistor having a fixed resistance, and the voltage across R1 may be output as a voltage signal to the amplifier.
  • the fixed resistance resistance R1 smaller than the equivalent resistance value can be selected according to the nominal equivalent resistance value of the resistance strain gauge under the condition that no deformation occurs, so that the R1 resistance The value is always lower than Rx, so that the resistance of the strain gauge is too large to be measured; the initial resistance of the adjustable resistor R2 can be set according to the resistance of the fixed resistance R1 and the input voltage range of the amplifier to obtain the match.
  • the voltage signal of the input voltage range of the amplifier when the resistance strain gauge is deformed and the amplitude of the voltage signal changes beyond the input voltage range of the amplifier, the resistance of the resistance adjustable resistor R2 is adjusted to change the amplitude of the voltage signal Uo so that It still meets the amplifier's input voltage range (eg, -14.5V to +14.5V).
  • the resistance adjustable resistor referred to in this paper refers to the dynamic adjustment of the strain gauge due to temperature drift or other attenuation when the production is completed, according to the potentiometer (for example, the digital potentiometer MCP41XX can be used). .
  • the equivalent resistance value change ⁇ R may range from 100 ⁇ to 1 M ⁇ .
  • this will cause the amplitude of the voltage signal output of the measuring circuit to vary by ⁇ U, and the input voltage range of the amplifier is limited, so that the input voltage cannot be accurately amplified; on the other hand, the equivalent resistance value In the case where the variation ⁇ R changes little, ⁇ U is too small, which may cause the amplifier circuit to have no output.
  • ⁇ U is too small, which may cause the amplifier circuit to have no output.
  • ⁇ U is lower than the lowest input voltage of the amplifier, resulting in no signal output; in the range of t2 to t3, ⁇ U exceeds the detectable voltage range of the amplifier, resulting in No signal output.
  • the voltage value across the resistance strain gauge is maintained at a relatively stable value by a fixed resistance resistor connected in parallel with the resistance strain gauge, and the voltage signal Uo is further set by setting the resistance adjustable resistor.
  • the amplitude is adjusted to fit the input voltage range of the amplifier, thereby reducing the drift and error of the detected signal.
  • the output voltage signal amplitude change ⁇ U is as shown in Fig. 12, and it has a stable output in the range of t0 to t1.
  • FIG. 13 is a block diagram showing the structure of a bridge type measuring circuit according to another embodiment of the present invention.
  • the lead wire at one end of the resistance strain gauge is connected to the DC power source VCC, and the other end is grounded in series with the first fixed resistance resistor R4; one end of the resistance adjustable resistor R2 is connected to the DC power source VCC, and the other end is connected to the second fixed resistance value.
  • the resistor R3 is connected in series and grounded; the third fixed resistance resistor R1 is connected in parallel with the lead of the resistance strain gauge; the voltage difference between the first fixed resistance resistor R4 and the second fixed resistance resistor R3 and the ground is output as a voltage signal Uo to Amplifier.
  • FIG. 14 is a block diagram showing the structure of a full bridge type measuring circuit according to still another embodiment of the present invention. It differs from the circuit shown in FIG. 13 in that the device includes two resistance strain gauges, the equivalent resistance of the strain gauges is Rx and Ry, and the second fixed resistance resistor R3 is connected in parallel with Ry.
  • the amplitude of the voltage signal Uo outputted by the measuring circuit can be adjusted to conform to the input voltage range of the amplifier, thereby reducing the detection signal. Drift and error, and can change the resistance of the resistance strain gauge to change the resistance of the resistance strain gauge after the tensile strain aging of the resistance strain gauge is repeated, and the stability of the measurement result is avoided to avoid the resistance. The effect of strain gauge aging.
  • the elastic resistance strain gauge can be disposed to be directly attached to the surface of the skin, and the resistance value is changed with breathing, by measuring circuits, amplifiers, analog-to-digital conversion circuits, and microprocessors.
  • the processing can obtain the resistance value change data of the elastic resistance strain gauge and convert it into the breathing curve data reflecting the breathing depth and frequency, thereby visually and accurately displaying the breathing state of the monitored object, and also performing measurement data on the host computer through the upper computer. Further analysis, when the frequency or depth in the respiratory curve data exceeds the preset threshold range, triggers a corresponding alarm to alert the user.
  • a portable respiratory monitoring system based on an elastic resistance strain gauge is similar in appearance to the structure shown in FIG.
  • the portable respiratory monitoring system according to the present embodiment includes: an elastic resistance strain gauge, a measuring circuit, an amplifier, an amplitude modulation circuit, an analog-to-digital conversion circuit, a microprocessor, a communication interface, and a DC power supply for supplying power, which are sequentially connected.
  • the elastic resistance strain gauge is directly attached to the skin surface, and the resistance value is changed with the breathing, and the resistance of the elastic resistance strain gauge can be obtained by the measurement circuit, the amplifier, the amplitude modulation circuit, the analog-to-digital conversion circuit, and the processing of the microprocessor.
  • the value changes data and is converted into respiratory curve data reflecting the depth and frequency of the breath, thereby visually and accurately displaying the breathing state of the monitored object.
  • the measurement data can be further analyzed by the upper computer, and the corresponding alarm is triggered when the frequency or depth in the respiratory curve data exceeds the preset threshold range to remind the user to pay attention.
  • the elastic resistance strain gauge is disposed to be directly adhered to the human skin (for example, directly attached to a position where the surface of the human body is undulating, such as between different ribs outside the lung, the abdomen, etc.).
  • the elastic structure stretches as the diaphragm contracts, and rebounds as the diaphragm relaxes, and the resistance value of the elastic strain gauge changes accordingly.
  • the intrathoracic pressure is lowered.
  • the air enters the lungs and the thorax expands.
  • the elastic resistance strain gauges spanning between the different ribs are stretched with the skin. The resistance of the equivalent resistance increases.
  • the resistance peak corresponds to the breathing depth; for different breathing frequencies, the frequency of the resistance peak changes corresponds to the breathing frequency.
  • the microprocessor is configured to calculate the resistance value of the equivalent resistance of the elastic resistance strain gauge according to the resistance value of the fixed resistance value and the resistance adjustable resistance and the voltage value of the DC power source, and generate the resistance value according to the resistance value of the equivalent resistance
  • the measurement data corresponding to the elastic strain gauge variable, and the respiratory curve data representing the respiratory depth and frequency are generated according to the peak value and the change frequency of the resistance value of the elastic resistance strain gauge in the measurement data.
  • the microprocessor can directly plot the curve based on the measured resistance data, and can further amplitude or frequency modulate the curve.
  • the generated breathing curve data can be directly displayed through a display connected to the microprocessor, for example, the measuring circuit, the amplifier, the amplitude modulation circuit, the analog-to-digital conversion circuit, the microprocessor, and the communication interface are disposed in the same integrated circuit, and the integration is performed.
  • the circuit is provided with one side or one end of the elastic strain gauge or embedded in the elastic strain gauge; in other embodiments, an ultra-thin integrated circuit and a flexible display screen may be used to be integrated in the non-conductive polymer layer of the elastic strain gauge. And providing a display screen on the opening or surface of the non-conductive polymer layer.
  • the generated breathing curve data may also be transmitted to other devices, such as a data analysis server, via a communication interface coupled to the microprocessor to further process or store the breathing curve data.
  • the portable respiratory monitoring system of the embodiment shown in FIG. 17 further includes a data analysis server, a database, and an alarm device connected to the communication interface through a network, wherein the data analysis server can store the generated respiratory curve data with the database.
  • the respiratory frequency data of each age group is compared.
  • the data analysis server When the respiratory frequency in the respiratory curve data exceeds the respiratory frequency range corresponding to the age of the monitored subject, the data analysis server generates an alarm message that the breathing is too slow or the breathing is too rapid, and occurs to the corresponding
  • the alarm device for example, a speaker for performing a voice alarm prompt, an LED alarm prompt light, a prompt interface in a human-machine interaction interface, and the like.
  • the database may store the respiratory reference frequency values of children of different ages as shown in Table 3 below, and may further store alarm time, alarm frequency, and the like for monitoring objects of different age stages.
  • the corresponding respiratory rate stored in the database is 30-40 times/minute, in order to avoid false positives and false negatives, it can be set at 2s, 3s or longer.
  • an alarm message is generated to trigger the alarm device.
  • the alarm information may also be generated based on the peak value of the waveform of the respiratory curve data. For example, when the frequency of the waveform change in the respiratory curve data is less than 30 times/minute, the respiratory rate of the monitored object is lower than the average value, which is too slow. , trigger the alarm device to alert the user. Similarly, if the detected waveform change frequency is higher than 40 times/min, it indicates that the respiratory rate of the monitored object is lower than the average value, which is too rapid, and triggers the alarm device to alert the user.
  • the database may also store respiratory amplitude data for each age group.
  • the data analysis server When the respiratory amplitude in the respiratory curve data exceeds the respiratory range corresponding to the age of the monitored subject, the data analysis server generates a breathing that is too weak or has a respiratory amplitude. Large alarm messages are generated and sent to the appropriate alarm device.

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Abstract

一种弹性电阻应变片及其制备方法，该弹性电阻应变片包括：不导电高分子层和导电高分子层，其中所述不导电高分子层由第一弹性高分子复合物材料制成，导电高分子层由第二弹性高分子复合物材料制成，所述第二弹性高分子复合物材料由第一弹性高分子复合物材料和导电填料制成，所述导电高分子层固化于不导电高分子层的表面。

Description

一种弹性电阻应变片及其制备方法和应用
相关引用
1、原受理机构名称为：中华人民共和国国家知识产权局，在先申请日为：2018年01月08日，在先申请号为：201810016225.4；
2、原受理机构名称为：中华人民共和国国家知识产权局，在先申请日为：2018年01月08日，在先申请号为：201810015675.1；
3、原受理机构名称为：中华人民共和国国家知识产权局，在先申请日为：2018年01月19日，在先申请号为：201810051942.0。
技术领域
本发明涉及电阻应变传感测量技术领域，尤其涉及一种弹性电阻应变片及其制备方法和应用。
背景技术
电阻应变片是一种常见的传感元件。电阻应变片受到的拉力、压力、扭矩、位移、加速度、温度等物理量发生变化时，其电阻的也会产生相应的变化，通过对其电阻的测量和输出，从而能够获得相应的物理量的测量值。
现有技术中常见的电阻应变片有金属应变片和半导体应变片。金属应变片是由康铜丝或镍铬丝绕成栅状，或用很薄的金属箔蚀刻成栅状夹在两层绝缘薄片中制成，再用镀银铜线与应变片丝栅连接作为电阻片引线，通过金属丝产生形变导致的电阻值的变化来检测应力的大小。半导体应变片是利用单晶硅的压阻效应制成的一种敏感元件，通过半导体材料产生形变而导致电阻率变化来检测应变片所受的压力、拉力等物理量。
金属应变片由于其成本较低，体积小、质量轻，广泛应用于称重领域，但存在灵敏度较低、机械滞后性较大的缺点。半导体应变片的精度、灵敏度比金属应变片高，可广泛应用于飞机、车辆、船舶等设备机械量测量，但存在温度稳定性差、较大的应力作用下非线性误差大、机械强度低等缺点。
申请公布号为CN102506693A的中国发明专利申请公开了一种基于石墨烯的应变测量或运动传感装置，其在柔性绝缘的基底上结合有一层或多层石墨烯薄膜层来检测应力变化。该方案通过贴附的方式将石墨烯薄膜层结合在基底上，由于柔性绝缘基底与石墨烯薄膜层的拉伸性能和应力变化差异明显，不仅存在形变量差异导致的测量结果准确度低的问题，而且整个装置的测量范围受限于形变量更小的石墨烯层。
申请公布号为CN104538088A的中国发明专利申请公开了一种高拉伸导电弹性体，虽然其通过在弹性体表面采用表面修饰技术引入芳香性基团来使弹性体表面与石墨烯导电层紧密结合，但紧密贴合并不能从根本上消除二者拉伸性能和应力变化的差异，也无法扩大导电层的形变量范围。并且，由于石墨烯导电层的不稳定、形变量范围较小，上述方案均受应用环境温度、应变片老化等影响较大，存在测量结果漂移且误差较大等技术问题。
发明内容
本发明的目的之一至少在于，针对如何克服上述现有技术存在的问题，提供一种弹性电 阻应变片及其制备方法和应用，该弹性电阻应变片的拉伸性能和应力变化一致度高，吸附性强，能够在增加应变片自身回弹性的同时，减小了漂移和误差，并且受温度的影响较小，具有更高的稳定性，可以作为弹性可拉伸电子器件的基础材料，广泛应用在医疗卫生、智能穿戴上。
为了实现上述目的，本发明采用的技术方案包括以下各方面。
一种弹性电阻应变片，其包括：不导电高分子层和导电高分子层，所述导电高分子层位于不导电高分子层的表面；其中，所述不导电高分子层由第一弹性高分子复合物材料制成；导电高分子层由第二弹性高分子复合物材料制成；所述第二弹性高分子复合物材料由第一弹性高分子复合物材料和导电填料制成。
一种弹性电阻应变片的制备方法，其包括：制备液态的第一弹性高分子复合物材料；将液态的第一弹性高分子复合物材料注入第一模具中，加热、固化第一弹性高分子复合物材料，以形成不导电高分子层；制备液态的第二弹性高分子复合物材料；将液态的第二弹性高分子复合物材料平铺于固化后的不导电高分子层上，加热、固化第二弹性高分子复合物材料，以形成导电高分子层并固化于不导电高分子层的表面。
一种用于电阻应变片输出调节的装置，其包括：依次连接的电阻应变片、测量电路、放大器、模数转换电路、微处理器、以及为所述装置供电的直流电源；其中，所述测量电路具有与电阻应变片的引线并联的第一电阻，以及与第一电阻串联的第二电阻，第一电阻的阻值小于电阻应变片的等效阻值的最小值以使测量电路根据电阻应变片的电阻值输出相应的电压信号；所述放大器，用于将测量电路输出的电压信号的幅值放大；模数转换电路，用于将放大器的输出信号转化为数字信号；所述微处理器用于根据第一电阻和第二电阻的阻值以及直流电源的电压值，计算电阻应变片的等效电阻的阻值，根据等效电阻的阻值变化生成与电阻应变片形变量相应的测量数据，并输出或存储所生产的测量数据。
一种基于弹性电阻应变片的便携式呼吸监测系统，其包括所述的装置；其中，所述弹性电阻应变片设置为直接与人体皮肤紧密粘贴的弹性结构体，并随着膈肌收缩而拉伸，随着膈肌松弛而回弹，弹性电阻应变片的电阻值随之变化；微处理器，用于根据固定阻值电阻和阻值可调电阻的阻值以及直流电源的电压值，计算弹性电阻应变片的等效电阻的阻值，根据等效电阻的阻值变化生成与弹性电阻应变片形变量相应的测量数据，并根据测量数据中弹性电阻应变片的电阻值的峰值及变化频率生成体现呼吸深度和频率的呼吸曲线数据。
综上所述，由于采用了上述技术方案，本发明至少具有以下有益效果：
通过在不导电高分子层上固化形成导电高分子层，使得导电高分子层和不导电高分子层的拉伸性能和应力变化一致度高，增加了应变片自身的回弹性，减小了漂移和误差；不导电高分子层采用弹性高分子复合物材料制成，能够检测相对于应变片敏感尺寸较大的形变量，且误差较小；同时所采用的高分子复合物材料受温度的影响较小，吸附性强，具有更高的稳定性，便于应用在医疗卫生、智能穿戴等新兴领域；通过将测量电路输出的电压信号的幅值调节至符合放大器的输入电压范围，从而减小检测信号的漂移和误差，并且可以在电阻应变片多次拉伸老化后，电阻应变片的等效电阻变化曲线发生变化时，通过改变阻值可调电阻的阻值来保持测量结果的稳定性，避免电阻应变片老化的影响；进一步通过将弹性电阻应变片 的电阻值变化数据转换为体现呼吸深度和频率的呼吸曲线数据，从而直观、准确地显示被监测对象的呼吸状态，而且还可以通过上位机对测量数据进行进一步的分析，在呼吸曲线数据中的频率或者深度超出预设的阈值范围时触发相应的报警，以提醒用户注意。
附图说明
图1是根据本发明实施例的弹性电阻应变片的剖面图。
图2是根据本发明实施例的弹性电阻应变片，其不导电高分子层和导电高分子层均设置为圆形。
图3是根据本发明实施例的弹性电阻应变片，其不导电高分子层设置为矩形，导电高分子层均设置为长条形。
图4是根据本发明实施例的弹性电阻应变片，其导电高分子层设置为U结构。
图5是根据本发明实施例的弹性电阻应变片，其导电高分子层设置为多个U形相连接的结构。
图6是根据本发明实施例的弹性电阻应变片，其导电高分子层设置有导线连接点。
图7是根据本发明实施例的弹性电阻应变片的制备方法的流程图。
图8是根据本发明实施例的输出调节的装置的结构示意图。
图9是根据本发明实施例的放大器的参考连接电路示意图。
图10是根据本发明一实施例的测量电路的结构示意图。
图11是现有技术之一输出的电压信号幅值变化示意图。
图12是根据本发明一实施例的测量电路的输出的电压信号幅值变化示意图。
图13是根据本发明另一实施例的测量电路的结构示意图。
图14是根据本发明又一实施例的测量电路的结构示意图。
图15是根据本发明实施例的吸气时便携式呼吸监测系统中弹性电阻应变片的粘贴示意图。
图16是根据本发明实施例的呼气时便携式呼吸监测系统中弹性电阻应变片的粘贴示意图。
图17是根据本发明一实施例的便携式呼吸监测系统的结构示意图。
具体实施方式
下面结合附图及实施例，对本发明进行进一步详细说明，以使本发明的目的、技术方案及优点更加清楚明白。应当理解，此处所描述的具体实施例仅用以解释本发明，并不用于限定本发明。
图1示出了根据本发明一实施例的弹性电阻应变片的剖面图。该实施例的弹性电阻应变片包括不导电高分子层和导电高分子层。
其中，所述不导电高分子层由第一弹性高分子复合物材料制成；导电高分子层由第二弹性高分子复合物材料制成；所述第二弹性高分子复合物材料由第一弹性高分子复合物材料和导电填料制成；
所述第一弹性高分子复合物材料为固化后能形成稳定表面且拉伸比为100％～500％的高分子复合物材料；所述导电高分子层固化于不导电高分子层的表面。在本发明中，不导电高 分子层作为导电高分子层的基底，两者紧密结合，拉伸性能和应力变化一致度高；当应变片所受应力加载结束后，除了导电高分子层自身具有的回弹力之外，不导电高分子层会额外对导电高分子层增加一个回弹力，使应变片能够在最快的速度内回复原状，减少应变片的漂移和误差。
在各种实际应用中，可根据不同的测量对象及范围选择硅胶、橡胶等作为第一弹性高分子复合物材料。例如，采用硅胶作为导电高分子层和不导电高分子层的基础复合物材料时，其拉伸比可达到500％(例如，材料在拉伸方向上的长度与材料未受拉伸时的长度之比)；采用橡胶时，拉伸比可达到200％～300％。选择不同的高分子复合物材料所制成应变片其灵敏度和线性度也不同。
并且，第二弹性高分子复合物材料由质量分数为70％～99.5％的第一弹性高分子复合物材料和质量分数为0.5％～30％的导电填料制成。其中，导电填料可以采用炭系导电填料或者金属系导电填料；炭系导电填料可包括炭黑、乙炔炭黑、石墨和碳纤维等；金属系导电填料有金粉、银粉、铜粉、铝粉、镍粉等。在本发明优选的实施例中，可以选用质量分数为10％～18％的炭黑作为导电填料，并采用质量分数为82％～90％的硅胶作为第一弹性高分子复合物材料来获取第二弹性高分子复合物材料。
当应变片采用不同的导电填料和/或不同比例的导电填料时，应变片的静态阻值、检测范围、灵敏度、线性度也不相同，导电填料的比例越高，应变片的静态阻值越低，灵敏度越高，但硬度也会越高。下表1示出了根据本发明优选的实施例中采用的多种不同质量分数的炭黑作为导电填料，并采用相应质量分数的硅胶作为第一弹性高分子复合物材料，所获取的具体多种不同导电性能的第二弹性高分子复合物材料的实验数据，以将弹性电阻应变片应用在不同的场景和位置。
表1
炭黑(质量分数，％) 电阻(kΩ) 工作电压(V)
10 1000～900 35～40
12 700～500 25～35
14 400～200 15～20
16 300～100 10～15
18 100～50 8～15
如图2、图3所示实施例的弹性电阻应变片的不导电高分子层和导电高分子层可以设置为圆形、矩形、方形、长条形等形状。根据应用场景的不同，例如为了分别对不同的肌肉群的形变进行测量，可以将不导电高分子层设置为沿着肌肉纹理的长条形并将导电高分子层设置为在不导电高分子层上沿长度范围内延伸分布，以提高检测的应力变化范围；并通过导电高分子层的端点或者边缘引出导线，通过与导线连接的电阻计量设备来测量导电高分子层的电阻变化，进而获取对于的应力变化值。
为了使应变片能够具有较好的贴合性，所述导电高分子层的厚度可为1um～100um，不导电高分子层的厚度可为0.3mm～2mm。较薄的应变片具有质量轻、弹性度高的优点，可应用于 医疗卫生、智能穿戴、航空航天等对应变片的稳定性、漂移和误差要求较高的场景。例如，可以将本发明提供的弹性电阻应变片制作为环形并佩戴在胸腔周围，通过测量应变片的阻值变化来获取呼吸频率和呼吸强度数据。或者，也可以将弹性电阻应变片直接贴附于其下具有较大血管的体表位置处，通过测量应变片的阻值变化来获取心率数据。在进一步的实施例中，可以将多个应变片制作为关节护套(例如，腕关节护套、膝关节护套、手套等)，通过多个应变片的阻值变化来获取关节的状态数据。
并且，为了提高导电高分子层的稳定性，减少环境和测量目标产生的影响，可以在所述导电高分子层的表面设置一保护层，该保护层为PET膜、PU膜或第一弹性高分子复合材料。
如图4、图5所示实施例的弹性电阻应变片的导电高分子层可以设置为U形或者由多个U形相连接的结构，从而可以在相同的接触面积(通常即不导电高分子层与测量目标之间的接触面积)下提高导电高分子层的形变量，从而提高应变片检测的灵敏度。在进一步的实施例中，导电高分子层可以设置为螺旋线形、等六边形蜂窝结构等。
如图6所示，在将导电高分子层设置为长条形的情况下，为了方便地引出导线，可以在长条形的导电高分子层的末端或者其他形状的边缘上设置与导线宽度匹配的导线连接点，以提高连接的可靠性。
图7示出了根据本发明一实施例的弹性电阻应变片的制备方法的流程图。该实施例的制备方法包括以下步骤：
步骤101：制备液态的第一弹性高分子复合物材料；
现有技术有多种可制备不导电高分子层的方案，例如，选择硅胶作为第一弹性高分子复合物材料，可以采用AB双组份硅胶来制备液态硅胶。具体地，可以取A组份零度液态硅胶和B组份的固化剂，搅拌均匀使A、B两组份充分混合来获取液态的硅胶。其中，A、B两组份的比例可以根据现有AB双组份硅胶的配方要求来设置为一比一或者其他比例。
步骤102：将液态的第一弹性高分子复合物材料注入第一模具中，加热、固化第一弹性高分子复合物材料，以形成不导电高分子层；
其中，第一模具可以采用与不导电高分子层相对应的形状，也可以采用易于生产的形状(例如矩形或方形)，然后通过切割的步骤来形成预设形状的不导电高分子层。加热温度通常小于100℃，加热温度越小所需加热时间越长，具体的加热温度和时间可根据实际情况进行选择。优选的加热温度为90℃，加热时间为30分钟，固化时间大于15分钟。
步骤103：制备液态的第二弹性高分子复合物材料；
例如，以硅胶作为第一弹性高分子复合物材料、炭黑作为导电填料，可以首先采用AB双组份硅胶来制备质量分数为的82％～90％液态硅胶，然后取质量分数为10％～18％的炭黑作为导电填料加入的液态硅胶中，搅拌均匀，使炭黑和液态硅胶充分混合，制成液态导电硅胶。在优选的实施例中，还可以在搅拌之前加入质量分数为0.5％～5％的分散剂(例如，二氧化硅、三氧化二铝)，在实施例中可以添加2％的二氧化硅作为分散剂，以使导电填料在硅胶中的导电更为均匀。
步骤104：将液态的第二弹性高分子复合物材料通过第二模具平铺于固化后的不导电高分子层上，加热、固化第二弹性高分子复合物材料，以形成导电高分子层并固化于不导电高 分子层的表面。
其中，第二模具可以采用与预设的导电高分子层相对应的形状(例如，为U形或者多个U形相连接)，以形成预设形状的导电高分子层。
或者，步骤104中也可以不采用第二模具，而是直接将液态的第二弹性高分子复合物材料平铺于固化后的不导电高分子层上，加热、固化第二弹性高分子复合物材料，再通过切割的方式获得所需的形状。
优选的加热温度为90℃，加热时间为30分钟，固化时间大于15分钟。通过直接在不导电高分子层上固化第二弹性高分子复合物材料来形成导电高分子层，使得导电高分子层和不导电高分子层的拉伸性能和应力变化高度一致，能够增加应变片自身的回弹性，并减小漂移和误差。
为了进一步减小弹性电阻应变片输出信号的漂移和误差，提高输出信号的稳定性，减少甚至避免弹性电阻应变片老化带来的漂移和误差影响，并提高输出信号的检测精度，本发明的公开了一种用于电阻应变片(包括前述各实施例的弹性电阻应变片和传统电阻应变片)输出调节的装置。
如图8所示，该实施例的装置包括依次连接的电阻应变片、测量电路、放大器、幅度调制电路、模数转换电路、微处理器、通信接口，以及为所述装置供电的直流电源。
其中，测量电路，具有与电阻应变片的引线并联的固定阻值电阻，以及与固定阻值电阻串联的阻值可调电阻，用于根据电阻应变片的电阻值输出相应的电压信号。
放大器，用于将电压信号的幅值放大至幅度调制电路的输入范围，例如，可以采用ADI公司的低噪声放大器AD8236、AD8634等，其具有9.7MHz带宽，输入电压噪声密度为10nV/
Figure PCTCN2018123167-appb-000001
在优选的实施例中，放大器电路采用AD8236，参考连接电路如图9所示，放大器的输出Vout＝G*(VINP-VINM)+VREF，其中，G为放大器的增益系数，VINP和VINM分别连接测量电路的输出端，VREF为参考电压(如5V)，C为旁路电容(如0.1μF)。G与增益设置电阻R G的关系如下表2所示，通过改变增益设置电阻R G将输出电压信号的幅值调节到符合信号调制电路的输入电压范围内，以减小检测信号的漂移和误差。
表2
RG(KΩ) G
210 6.0
105 9.0
84.5 10.0
9.31 50.1
4.42 100.0
2.15 200.3
幅度调制电路，包括三极管和LC谐振回路，用于通过高频载波振荡器产生的等幅载波对输入的电压信号进行非线性频率变换，并输出调幅波。然而，幅度调制电路为可选的，在各种实施方式中，可以通过设置放大器的增益系数来将电压信号的幅值放大至模数转换电路 的输入范围之内。
模数转换电路，用于将调幅波转换为数字信号。例如，可以采用Motorola公司MC14433芯片和外围电阻、电容来构成模数转换电路。
微处理器，用于根据固定阻值电阻和阻值可调电阻的阻值以及直流电源的电压值，计算电阻应变片的等效电阻的阻值，并根据等效电阻的阻值变化生成与电阻应变片形变量相应的测量数据。例如，微处理器可以采用TI公司的16位RISC单片机MSP-430F413。
对于生成的测量数据可以通过与微处理器连接的显示器(例如，与电阻应变片设置为一体结构的LED显示屏)直接显示，也可以通过与微处理器连接的通信接口将生成的测量数据发送给其他设备，例如数据分析服务器，以对测量数据进行进一步处理或者存储。
图10示出了根据本发明一实施例的测量电路的结构示意图。其中，电阻应变片的等效电阻表示为Rx；电阻应变片一端的引线连接至直流电源VCC，另一端与阻值可调电阻R2连接；阻值可调电阻R2的一端与电阻应变片串联，另一端接地；固定阻值电阻R1与电阻应变片的引线并联；将阻值可调电阻R2两端的电压Uo作为电压信号输出至放大器。在其他实施例中，也可以将电阻R2设置为阻值固定的电阻，并将R1两端的电压作为电压信号输出至放大器。
在针对各种不同种类电阻应变片的应用中，首先可以依据电阻应变片在未发生形变条件下的标称等效电阻值来选择小于该等效电阻值的固定阻值电阻R1，使得R1阻值始终低于Rx，避免应变片阻值变化太大到无法测量；阻值可调电阻R2的初始阻值可以根据固定阻值电阻R1的阻值和放大器的输入电压范围来设置，以获取符合放大器的输入电压范围的电压信号；在电阻应变片发生形变且电压信号的幅值变化超出放大器的输入电压范围时，调节阻值可调电阻R2的阻值来改变电压信号Uo的幅值以使其仍符合放大器的输入电压范围(例如，-14.5V～+14.5V)。从此过程可以看出，本文所指阻值可调电阻，是指生产完成时，由于应变片会随着温度漂移或者其他衰减，可根据电位器(例如，可采用数字电位器MCP41XX)进行动态调整。
例如，对于灵敏度较高的电阻应变片(例如，上述实施例中的弹性电阻应变片)，其等效电阻值变化△R的范围可以达到100Ω～1MΩ。一方面，这会导致测量电路输出的电压信号幅值变化△U的漂移范围很广，而放大器的输入电压范围有限，无法对输入的电压进行准确地放大；另一方面，在等效电阻值变化△R变化较小的情况下，△U过小，可能会导致放大器电路无任何输出。如图11所示，在t0～t1的范围内，△U低于放大器的最低输入电压，导致无信号输出；在t2～t3的范围内，△U超过放大器的能够检测到的电压范围，导致无信号输出。通过本发明的上述实施例，一方面通过与电阻应变片并联的固定阻值电阻来将电阻应变片两端的电压值保持在相对稳定的值，并进一步通过设置阻值可调电阻将电压信号Uo的幅值调节到符合放大器的输入电压范围内，从而减小检测信号的漂移和误差。其输出的电压信号幅值变化△U如图12所示，其在t0～t1的范围内均有稳定的输出。
图13示出了根据本发明另一实施例的桥式测量电路的结构示意图。其中，电阻应变片一端的引线连接至直流电源VCC，另一端与第一固定阻值电阻R4串联后接地；阻值可调电阻R2的一端连接至直流电源VCC，另一端与第二固定阻值电阻R3串联后接地；第三固定阻值电阻R1与电阻应变片的引线并联；将第一固定阻值电阻R4和第二固定阻值电阻R3与地之 间的电压差作为电压信号Uo输出至放大器。
图14示出了根据本发明又一实施例的全桥式测量电路的结构示意图。其与图13所示电路的不同之处在于，该装置包括两个电阻应变片，电阻应变片的等效电阻为Rx和Ry，第二固定阻值电阻R3与Ry并联。
上述实施例中，通过第一至第三固定阻值电阻以及阻值可调电阻，不仅可以将测量电路输出的电压信号Uo的幅值调节至符合放大器的输入电压范围，从而减小检测信号的漂移和误差，并且可以在电阻应变片多次拉伸老化后，电阻应变片的等效电阻变化曲线发生变化时，通过改变阻值可调电阻的阻值来保持测量结果的稳定性，避免电阻应变片老化的影响。
在本发明上述实施例的各种应用中，可以将弹性电阻应变片设置为直接粘贴在皮肤表面，随着呼吸而改变电阻值，通过测量电路、放大器、模数转换电路、以及微处理器的处理，可以获取弹性电阻应变片的电阻值变化数据，并转换为体现呼吸深度和频率的呼吸曲线数据，从而直观、准确地显示被监测对象的呼吸状态，而且还可以通过上位机对测量数据进行进一步的分析，在呼吸曲线数据中的频率或者深度超出预设的阈值范围时触发相应的报警，以提醒用户注意。
根据本发明一实施例的基于弹性电阻应变片的便携式呼吸监测系统，与图8所示的结构在外形上类似。但是，根据本实施例的便携式呼吸监测系统包括：依次连接的弹性电阻应变片、测量电路、放大器、幅度调制电路、模数转换电路、微处理器、通信接口，以及用于供电的直流电源。其中，弹性电阻应变片直接粘贴在皮肤表面，随着呼吸而改变电阻值，通过测量电路、放大器、幅度调制电路、模数转换电路、以及微处理器的处理，可以获取弹性电阻应变片的电阻值变化数据，并转换为体现呼吸深度和频率的呼吸曲线数据，从而直观、准确地显示被监测对象的呼吸状态。而且还可以通过上位机对测量数据进行进一步的分析，在呼吸曲线数据中的频率或者深度超出预设的阈值范围时触发相应的报警，以提醒用户注意。
如图15和图16所示，弹性电阻应变片设置为直接与人体皮肤紧密粘贴(例如，直接粘贴在人体表面呼吸起伏较大的位置，如肺部外不同的肋骨之间、腹部等)的弹性结构体，并随着膈肌收缩而拉伸，随着膈肌松弛而回弹，弹性电阻应变片的电阻值随之变化。如图15所示，当膈肌收缩时，胸内压力降低，为维持压力平衡，空气进入肺内，胸廓扩张，此时横跨不同肋骨之间的弹性电阻应变片随着皮肤而拉伸，其等效电阻的阻值随之增大。如图16所示，当膈肌松弛时，胸内压力升高，促进气体排出肺外，胸腔缩小，此时弹性电阻应变片回弹，其等效电阻的阻值随之减小。而且，对于不同的呼吸深度，电阻峰值与呼吸深度相对应；对于不同的呼吸频率，电阻峰值变化的频率与呼吸频率相对应。
微处理器，用于根据固定阻值电阻和阻值可调电阻的阻值以及直流电源的电压值，计算弹性电阻应变片的等效电阻的阻值，并根据等效电阻的阻值变化生成与弹性电阻应变片形变量相应的测量数据，并根据测量数据中弹性电阻应变片的电阻值的峰值及变化频率生成体现呼吸深度和频率的呼吸曲线数据。例如，微处理器可以直接根据测量的电阻数据绘制曲线，还可以进一步对曲线进行幅度或者频率调制。
对于生成的呼吸曲线数据可以通过与微处理器连接的显示器直接显示，例如，将测量电路、放大器、幅度调制电路、模数转换电路、微处理器、通信接口设置在同一集成电路中， 将集成电路设置弹性应变片的一侧或一端或者嵌入在弹性应变片中；在其他实施方式中，也可以采用超薄集成电路和柔性显示屏，以集成在弹性电阻应变片的不导电高分子层中，并在不导电高分子层上开口或表面上设置显示屏。在其他实施例中，也可以通过与微处理器连接的通信接口将生成的呼吸曲线数据发送给其他设备，例如数据分析服务器，以对呼吸曲线数据进行进一步处理或者存储。
如图17所示实施例的便携式呼吸监测系统中，进一步包括通过网络与通信接口连接的数据分析服务器、数据库以及警报设备，其中，数据分析服务器可以通过将生成的呼吸曲线数据与数据库中存储的各年龄段呼吸频率数据进行对比，当呼吸曲线数据中的呼吸频率超出与监测对象的年龄相应的呼吸频率范围时，数据分析服务器生成呼吸过于缓慢或者呼吸过于急促的告警信息，并发生给相应的警报设备，例如，用于进行语音告警提示的扬声器、LED告警提示灯、人机交互界面中的提示界面等。例如，对于以儿童为监测对象的应用场景中，数据库中可以存储如下表3所示的各年龄段儿童呼吸参考频率值，可进一步存储针对不同年龄阶段的监测对象设置报警时间、报警频率等。
表3
年龄 呼吸频率(次/分钟)
<1月 40～45
<1岁 30～40
2～3岁 25～30
4～7岁 20～25
以监测的对象为8个月大的新生婴儿为例，数据库中存储的相应呼吸频率是30～40次/分钟，则为了避免出现误报和漏报，可设置在2s、3s或更长时间段内未检测到呼吸曲线数据存在波形变化，则生成告警信息，触发警报设备。也可以之间基于呼吸曲线数据的波形峰值变化频率来生成告警信息，例如，当呼吸曲线数据中的波形变化频率小于30次/分钟，则说明被监测对象的呼吸速率低于平均值，过于缓慢，触发警报设备提醒用户注意。同理，若检测的波形变化频率高于40次/分钟，则说明被监测对象的呼吸速率低于平均值，过于急促，触发警报设备提醒用户注意。
在进一步的实施例中，数据库还可以存储各年龄段呼吸幅度数据，当呼吸曲线数据中的呼吸幅度超出与监测对象的年龄相应的呼吸幅度范围时，数据分析服务器生成呼吸过于微弱或者呼吸幅度过大的告警信息，并发生给相应的警报设备。而且，也可以结合呼吸频率和呼吸幅度阈值范围，并设置一定的观察时间，例如，当呼吸频率和/或呼吸幅度在3分钟之内恢复到预设的范围之内时，则自动取消告警提示。
以上所述，仅为本发明具体实施方式的详细说明，而非对本发明的限制。相关技术领域的技术人员在不脱离本发明的原则和范围的情况下，做出的各种替换、变型以及改进均应包含在本发明的保护范围之内。

Claims (12)

  1. 一种弹性电阻应变片，其特征在于，包括：不导电高分子层和导电高分子层，所述导电高分子层位于不导电高分子层的表面；
    其中，所述不导电高分子层由第一弹性高分子复合物材料制成；导电高分子层由第二弹性高分子复合物材料制成；所述第二弹性高分子复合物材料由第一弹性高分子复合物材料和导电填料制成。
  2. 根据权利要求1所述的弹性电阻应变片，其特征在于，所述第一弹性高分子复合物材料、第二弹性高分子复合物材料均为固化后能形成稳定表面且拉伸比为100％～500％的高分子复合物材料；优选的，所述第一弹性高分子复合物材料为硅胶或橡胶；优选的，不导电高分子层设置为沿着肌肉纹理的长条形，并且导电高分子层设置为在不导电高分子层上在长条形的长度范围内延伸分布，以提高检测的应力变化范围。
  3. 根据权利要求1或2所述的弹性电阻应变片，其特征在于，所述第二弹性高分子复合物材料由质量分数为70％～99.5％的第一弹性高分子复合物材料和质量分数为0.5％～30％的导电填料制成；
    其中，所述导电填料包括所述导电填料包括炭系导电填料和/或金属系导电填料；所述炭系导电填料包括炭黑、乙炔炭黑、石墨、碳纳米管、碳纤维中的一种或多种，所述金属系导电填料包括金粉、银粉、铜粉、铝粉、镍粉中的一种或多种；优选的，所述第二弹性高分子复合物材料由质量分数为82％～90％的第一弹性高分子复合物材料和质量分数为10％～18％的炭黑或碳纳米管制成；优选的，所述第二弹性高分子复合物材料还包括质量分数为0.5％～5％且作为分散剂的二氧化硅或三氧化二铝。
  4. 根据权利要求1至3中任一项所述的弹性电阻应变片，其特征在于，所述导电高分子层的厚度为1um～100um，不导电高分子层的厚度为0.3mm～2mm；优选的，所述导电高分子层的表面还设置有一保护层，该保护层为PET膜、PU膜或第一弹性高分子复合材料。
  5. 一种弹性电阻应变片的制备方法，其特征在于，所述制备方法包括：
    制备液态的第一弹性高分子复合物材料；将液态的第一弹性高分子复合物材料注入第一模具中，加热、固化第一弹性高分子复合物材料，以形成不导电高分子层；
    制备液态的第二弹性高分子复合物材料；将液态的第二弹性高分子复合物材料平铺于固化后的不导电高分子层上，加热、固化第二弹性高分子复合物材料，以形成导电高分子层并固化于不导电高分子层的表面。
  6. 根据权利要求5所述的制备方法，其特征在于，所述制备方法包括：将液态的第二弹性高分子复合物材料通过第二模具平铺于固化后的不导电高分子层上，加热、固化第二弹性高分子复合物材料，以形成导电高分子层并固化于不导电高分子层的表面；其中，所述第二模具采用与预设的导电高分子层相对应的形状，以形成预设形状的导电高分子层；
    优选的，将液态的第二弹性高分子复合物材料平铺于固化后的不导电高分子层上，加热、固化第二弹性高分子复合物材料，再通过切割的方式获得所需的形状。
  7. 一种用于电阻应变片输出调节的装置，其特征在于，包括：依次连接的电阻应变片、测量电路、放大器、模数转换电路、微处理器、以及为所述装置供电的直流电源；
    其中，所述测量电路具有与电阻应变片的引线并联的第一电阻，以及与第一电阻串联的 第二电阻，第一电阻的阻值小于电阻应变片的等效阻值的最小值以使测量电路根据电阻应变片的电阻值输出相应的电压信号；
    所述放大器，用于将测量电路输出的电压信号的幅值放大；模数转换电路，用于将放大器的输出信号转化为数字信号；
    所述微处理器用于根据第一电阻和第二电阻的阻值以及直流电源的电压值，计算电阻应变片的等效电阻的阻值，根据等效电阻的阻值变化生成与电阻应变片形变量相应的测量数据，并输出或存储所生产的测量数据。
  8. 根据权利要求7所述的装置，其特征在于，所述电阻应变片为根据权利要求1至4中任一项所述的弹性电阻应变片。
  9. 根据权利要求7所述的装置，其特征在于，所述测量电路包括一个阻值可调电阻和一个固定阻值电阻；其中，电阻应变片一端的引线连接至直流电源，另一端与阻值可调电阻连接；阻值可调电阻的一端与电阻应变片串联，另一端接地；固定阻值电阻与电阻应变片的引线并联；将阻值可调电阻两端的电压作为电压信号输出至放大器；
    或者，所述测量电路包括一个阻值可调电阻和三个固定阻值电阻；其中，电阻应变片一端的引线连接至直流电源，另一端与第一固定阻值电阻串联后接地；阻值可调电阻的一端连接至直流电源，另一端与第二固定阻值电阻串联后接地；第三固定阻值电阻与电阻应变片的引线并联；将第一固定阻值电阻和第二固定阻值电阻与地之间的电压差作为电压信号输出至放大器；
    或者，所述装置包括两个电阻应变片，所述测量电路包括一个阻值可调电阻和三个固定阻值电阻；其中，第一电阻应变片一端的引线连接至直流电源，另一端与第一固定阻值电阻串联后接地；阻值可调电阻的一端连接至直流电源，另一端与第二固定阻值电阻串联后接地；第三固定阻值电阻与电阻应变片的引线并联；第二电阻应变片与第二固定阻值电阻并联；将第一固定阻值电阻和第二固定阻值电阻与地之间的电压差作为电压信号输出至放大器；优选的，在电阻应变片发生形变且电压信号的幅值变化超出放大器的输入电压范围时，调节阻值可调电阻的阻值来改变电压信号的幅值以符合放大器的输入电压范围。
  10. 一种基于弹性电阻应变片的便携式呼吸监测系统，其特征在于，所述系统包括根据权利要求7至9中任一项所述的装置；
    其中，所述弹性电阻应变片设置为直接与人体皮肤紧密粘贴的弹性结构体，并随着膈肌收缩而拉伸，随着膈肌松弛而回弹，弹性电阻应变片的电阻值随之变化；微处理器，用于根据固定阻值电阻和阻值可调电阻的阻值以及直流电源的电压值，计算弹性电阻应变片的等效电阻的阻值，根据等效电阻的阻值变化生成与弹性电阻应变片形变量相应的测量数据，并根据测量数据中弹性电阻应变片的电阻值的峰值及变化频率生成体现呼吸深度和频率的呼吸曲线数据。
  11. 根据权利要求10所述的系统，其特征在于，所述测量电路、放大器、模数转换电路、微处理器、通信接口设置在同一集成电路中，且该集成电路设置在弹性电阻应变片的不导电高分子层中，并在不导电高分子层上开口或者表面设置显示屏，以直接显示呼吸曲线数据；优选的，所述放大器电路采用ADI公司的低噪声放大器AD8236，相应的旁路电容为0.1μF， 参考电压为5V，增益设置电阻为2.15～210KΩ，增益系数为6.0～200.3。
  12. 根据权利要求11所述的系统，其特征在于，所述系统进一步包括通过网络与通信接口连接的数据分析服务器、数据库以及警报设备；
    其中，数据分析服务器通过将生成的呼吸曲线数据与数据库中存储的各年龄段呼吸频率数据进行对比，当呼吸曲线数据中的呼吸频率超出与监测对象的年龄相应的呼吸频率范围时，数据分析服务器生成呼吸过于缓慢或者呼吸过于急促的告警信息，并发生给相应的警报设备；优选的，所述数据库还用于存储各年龄段呼吸幅度数据；当呼吸曲线数据中的呼吸幅度超出与监测对象的年龄相应的呼吸幅度范围时，数据分析服务器生成呼吸过于微弱或者呼吸幅度过大的告警信息，并发生给相应的警报设备；优选的，所述警报设备包括用于进行语音告警提示的扬声器、LED告警提示灯、以及人机交互界面中的提示界面。
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