Sensor with anti-interference performance and preparation method and application thereof

Abstract

The invention belongs to the field of sensors, and particularly relates to a sensor with anti-interference performance and a preparation method and application thereof, the sensor comprises a substrate, the substrate is provided with a plurality of installation areas, the installation areas are used for installing LED elements and PD elements, the different installation areas are mutually independent, and the installation areas are mutually independent. The mounting area is formed by cutting and bending the substrate at the corresponding position, the mounting area comprises a bent connecting edge and a mounting plate, the mounting plate is connected with the substrate through the bent connecting edge and is parallel to the substrate, and the height of the mounting plate is equivalent to the thickness of the corresponding LED element or PD element. And after the LED element or the PD element is mounted at the bottom of the mounting plate, the bottom of the LED element or the PD element is flush with the substrate. The sensor not only can reduce interference signals from the environment, but also is low in cost.

Description

Technical Field

[0001] The present invention belongs to the field of sensors, and particularly relates to a sensor with anti-interference performance, a preparation method thereof, and an application thereof. Background Art

[0002] NIRS (Near Infrared) is widely used in medical, beauty and other fields due to its good penetrability, which can penetrate human tissues and feedback corresponding signals, such as for finger pulse oximetry, tissue oxygen measurement, hemoglobin concentration change, optoelectronic beauty, etc. Among them, the basic principle of tissue oxygen measurement is to irradiate a group of infrared rays into human tissues, and after the light passes through the tissues, it is received from another place. By analyzing the intensity of the received light and its changes, the tissue oxygen saturation is analyzed.

[0003] See Figure 1 As shown, when infrared rays pass through human tissues, they will be absorbed, so the light intensity received at the receiving end is weak, and can even be attenuated to the order of 10-12W. In order to effectively collect such a weak light signal, the light signal receiving end not only needs to have high sensitivity, but also needs to minimize the interference signals from the environment, so as to ensure the signal-to-noise ratio of the useful signal.

[0004] In order to minimize the interference signals from the environment, the commonly used technical means are:

[0005] (1) Shielding PD scheme. This scheme uses a transparent conductive material or a mesh conductor to completely wrap the PD to form a Faraday cage, so as to achieve electromagnetic shielding and reduce interference. However, this method has an attenuation problem, resulting in a decrease in the signal-to-noise ratio.

[0006] (2) Keep away from human tissue as much as possible scheme. This scheme is to separate the sensor that receives light from human tissues by a small distance by increasing the thickness of the foam, so as to reduce interference. However, since the sensor and the measured human tissue cannot be too far apart and still adopt the fitting measurement method, this scheme has limited effect in suppressing external interference and is not ideal.

[0007] (3) Optical modulation scheme. This scheme is to modulate the emitted infrared rays first, and then demodulate the light signal of a specific frequency at the receiving end, so as to achieve the filtering of electromagnetic interference. Although this scheme can filter out most of the electromagnetic interference and has a good effect, since the modulation and demodulation of the light signal require additional functional circuits, there is a problem of increased cost; in addition, the signal bandwidth of this method is limited, which will affect the realization of some measurement functions. Summary of the Invention

[0008] To improve the deficiencies of the prior art, the present invention provides a sensor with anti-interference performance, its preparation method and application. This sensor can not only reduce the interference signals from the environment, but also has a relatively low cost.

[0009] In a first aspect, the present invention provides a sensor with anti-interference performance. The sensor includes a substrate, and a plurality of mounting areas are provided on the substrate. The mounting areas are used for mounting LED elements and PD elements. Different mounting areas are independent of each other. The mounting areas are formed by cutting and bending the corresponding parts of the substrate. The mounting area includes a bent connecting edge and a mounting plate. The mounting plate is connected to the substrate through the bent connecting edge. The mounting plate is parallel to the substrate, and the height of the mounting plate is equivalent to the thickness of the corresponding LED element or PD element. After the LED element or PD element is mounted at the bottom of the mounting plate, the bottom of the LED element or PD element is flush with the substrate.

[0010] According to an embodiment of the present invention, when the substrate is attached to the skin, the bottom of the LED element or PD element is attached to the skin.

[0011] According to an embodiment of the present invention, on the non-mounting area of the substrate, a conductive film is provided on the surface attached to the skin. The conductive film is used to form a reference signal plane. Specifically, when the conductive film contacts the skin, a parasitic capacitance is generated.

[0012] According to an embodiment of the present invention, the substrate is an FPC board (Flexible Printed Circuit).

[0013] According to an embodiment of the present invention, the conductive film is a conductive adhesive layer and / or a metal layer, such as a composite layer of a conductive adhesive layer, a metal layer and an adhesive layer.

[0014] According to an embodiment of the present invention, a protective film is provided on the top of the conductive film.

[0015] According to an embodiment of the present invention, the FPC board includes a lower electromagnetic shielding film, a lower character printing layer, a lower solder mask layer, a lower copper layer, a substrate film, an upper copper layer, an upper solder mask layer, an upper character printing layer, and an upper electromagnetic shielding film arranged in sequence from bottom to top. The electromagnetic shielding layer includes an insulating layer, a conductive film and a protective film.

[0016] According to an embodiment of the present invention, the substrate film is selected from PI or polyester film PET, such as PI (polyimide).

[0017] According to an embodiment of the present invention, the installation area is rectangular or other structures. When it is rectangular, the installation area is formed by cutting three sides of the rectangle connected in sequence and bending along the uncut side; when it is other structures, the installation area is formed by cutting along the corresponding structure, retaining at least a part of the area connected to the substrate, and bending along the connected side.

[0018] As an example, three sides of the LED installation area on the FPC board are cut, and the other side is used as the folding edge. The cut FPC is bent upward along the folding edge to form a horizontal installation plate (sinking area) and a bent connecting edge. Among them, the installation plate is parallel to the FPC board, and the bent connecting edge is inclined to connect the installation plate and the FPC board. The flexibility of the FPC board is used to sink the installation plate, and the LED component is arranged at the center of the installation plate. When the FPC board is attached to the skin of the person to be measured, the LED component is in direct contact with the skin.

[0019] According to an embodiment of the present invention, the sensor further includes a tissue oxygen calculation module, and the sensor is electrically connected to the tissue oxygen calculation module.

[0020] According to an embodiment of the present invention, the tissue oxygen calculation module is used to receive the signals collected by the sensor and calculate the signals to obtain the blood oxygen value.

[0021] According to an embodiment of the present invention, the PD element, the conductive film are electrically connected to the tissue oxygen calculation module.

[0022] According to an embodiment of the present invention, the PD element generates a capacitance effect with the human tissue to form a parasitic capacitance C2; the conductive film generates a parasitic capacitance C1 with the human tissue.

[0023] According to an embodiment of the present invention, the sensor further includes an anti-interference circuit, and the PD element and the conductive film are electrically connected to the tissue oxygen calculation module through the anti-interference circuit.

[0024] According to an embodiment of the present invention, the anti-interference circuit is used to cancel out the signal superimposed by the PD element and the parasitic capacitance C2 and the interference signal of the parasitic capacitance C1 generated by the human tissue to obtain a denoised signal, and then transmit it to the tissue oxygen calculation module.

[0025] According to an embodiment of the present invention, the anti-interference circuit includes a first signal pre-conditioner, a second signal pre-conditioner, an inverter and an ADC. The parasitic capacitance C2 is in parallel with the PD, and the formed tissue oxygen PD signal enters the tissue oxygen calculation module through the first signal pre-conditioner and the ADC; the parasitic capacitance C1 is grounded through a resistor R, and the formed reference signal enters the tissue oxygen calculation module through the second signal pre-conditioner, the inverter and the ADC.

[0026] According to an embodiment of the present invention, after the output of the first signal pre-conditioner and the output of the inverter pass through an adder, the signal is sent to the ADC.

[0027] According to an embodiment of the present invention, the first signal pre-conditioner and the second signal pre-conditioner employ a signal processing circuit composed of operational amplifiers.

[0028] According to an embodiment of the present invention, the tissue oxygen calculation module includes a calibration unit, and the calibration unit is used to calibrate the installation errors of the LED element and the PD element.

[0029] According to an embodiment of the present invention, the installation error is the difference between the theoretical installation position of the LED element and the PD element in the corresponding installation area and the actual position in the sinking area.

[0030] According to an embodiment of the present invention, the calculation method of the installation error includes the following steps:

[0031] S1. Taking the center point of the LED element or the PD element before the mounting plate is folded as point a, and the center point of the LED element or the PD element after folding as point b, through equivalent translation, translate the center points a and b to the origin where the FPC board and the bent connection edge intersect, and in the coordinate system with the plane of the FPC board as the X-axis. Among them, b is translated to the intersection point b' of the mounting plate and the bent connection edge, and a is translated to the corresponding point a' on the X-axis;

[0032] S2. Calculate the length of the line segment ca', where the c point is the projection of the b' point on the X-axis; the angle of ∠b'Oa' is α; the height of the element, that is, the length of the line segment b'c, is the thickness h of the corresponding element. The length calculation formula of the X-axis offset ca' of the element:

[0033]

[0034] In a second aspect, the present invention provides a preparation method of a sensor with anti-interference performance, including the following steps:

[0035] Determine the installation area on the substrate, cut and bend the substrate corresponding to the installation area to form the installation area, and install the corresponding LED element or PD element in the installation area. The installation area includes a bent connection edge and a mounting plate, and the height of the mounting plate is equivalent to the thickness of the corresponding LED element or PD element.

[0036] According to an embodiment of the present invention, the method further includes setting a conductive film on the surface of the non-installation area on the substrate that fits the skin, and the conductive film has the definition as described above.

[0037] According to an embodiment of the present invention, the method further includes setting an anti-interference circuit.

[0038] In a third aspect, the present invention also provides an application of the above-mentioned sensor in near-infrared signal acquisition, such as for measuring blood oxygen concentration, finger pulse oxygen, tissue oxygen, and hemoglobin concentration.

[0039] Beneficial effects

[0040] 1. The sensor with anti-interference performance in the present invention includes a substrate, on which several installation areas are provided for installing LED elements and PD elements. Different installation areas are independent of each other. The installation area includes a bent connecting edge and an installation plate. The installation plate is connected to the substrate through the bent connecting edge. The installation plate is parallel to the substrate, and the height of the installation plate is equivalent to the thickness of the corresponding LED element or PD element. After installing the LED element or PD element at the bottom of the installation plate, the bottom of the LED element or PD element is flush with the substrate. Thus, the LED element and the PD element can be directly attached to the skin without the problem of inability to attach. Moreover, the light emitted by the LED element and the PD element directly acts on the skin, not only without affecting the light-emitting and light-receiving directions, but also avoiding the attenuation of the light signal during transmission. At the same time, the light emitted by the LED element can directly act on the skin without the need to punch holes in the PFC. Therefore, the sensor structure of the present invention is relatively simple, and the preparation method is simple with low cost.

[0041] 2. The present invention uses existing standard positive-attached components to achieve the effect of reverse attachment, thus avoiding the high cost of component customization and reducing costs.

[0042] 3. A conductive film is provided on the surface of the FPC of the present invention. The conductive film, such as a large-area copper foil, can be used as a reference signal plane to extract the reference plane signal and apply it in interference suppression measures. On the premise of ensuring the signal bandwidth and the detection light intensity, the interference signal is minimized as much as possible to make the effective signal have a strong enough signal-to-noise ratio.

[0043] 4. The sensor of the present invention further includes an anti-interference circuit for canceling out the interference signal generated by the parasitic capacitance C1 of the human tissue from the signal obtained by superimposing the PD element and the parasitic capacitance C2, and obtaining a denoised signal, which is then transmitted to the tissue oxygen calculation module. The inverter can reverse the positive and negative polarities of the signal. Therefore, after the interference signal output by the inverter is added to the interference signal superimposed in the PD signal, they cancel each other out to zero, thus achieving the purpose of eliminating the interference signal. Description of the drawings

[0044] Figure 1 It is an optical path diagram for tissue oxygen measurement;

[0045] Figure 2 It is a schematic structural diagram of an electronic component;

[0046] Figure 3 It is a cross-sectional view of a positive-attached LED;

[0047] Figure 4 Optical path diagram of a positive-mounted LED

[0048] Figure 5 Optical path diagram of a reverse-mounted LED

[0049] Figure 6 Structural schematic diagram of the sensor in Embodiment 1

[0050] Figure 7 Structural schematic diagram of the cooperation between the LED element and the sinking area in Embodiment 1

[0051] Figure 8 Structural schematic diagram of the cooperation between the PD element and the sinking area in Embodiment 1

[0052] Figure 9 Bottom view and side view of the sensor with multiple LED elements in Embodiment 1

[0053] Figure 10 Coordinate schematic diagram of the center offset

[0054] Figure 11 Coordinate diagram for calculating the offset by establishing a rectangular coordinate system in the side view

[0055] Figure 12 Structural schematic diagram of the sensor attached to the skin

[0056] Figure 13 Structural schematic diagram of the sensor with one LED and two PDs

[0057] Figure 14 Structural schematic diagram of parasitic capacitance formed on the sensor

[0058] Figure 15 Topological structure diagram of the anti-interference circuit

[0059] Figure 16 Schematic diagram of the anti-interference circuit

[0060] Figure 17 For Figure 13 Physical diagram Detailed implementation manners

[0061] The following will further elaborate on the structure and method of the present invention in combination with specific embodiments. It should be understood that the following embodiments are only for exemplarily illustrating and explaining the present invention, and should not be construed as limiting the protection scope of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope intended to be protected by the present invention.

[0062] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0063] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "mounted", "connected", and "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0064] Embodiment 1

[0065] Generally, due to the certain height of electronic components, after the electronic components are soldered on the PCB (Printed Circuit Board), they will be higher than the PCB surface by a certain distance. As Figure 2 , Figure 3 and Figure 4 shown, when the FPC (Flexible Printed Circuit) is attached to the human skin downward, due to the certain height of the LED and PD components (precision diodes, the PD components in this embodiment refer to optical receivers), poor attachment or inability to attach will occur.

[0066] One current method to solve this problem is to use reverse-mounted components: specifically, the components are selected in a reverse-mounted package form. The installation of the above-mentioned LED and PD components will be moved to the upper surface of the FPC board. Since the light-emitting and light-receiving directions of the LED and PD remain unchanged and are still vertically downward, holes need to be drilled on the upper surface of the PFC substrate to allow the light to penetrate. As Figure 5 shown, however, the method of using reverse-mounted components requires the use of special reverse-mounted components, the selection range is relatively narrow, and customization may be required, resulting in higher costs.

[0067] The specific implementation method of the reverse-mounting effect scheme of the forward-mounted LED is provided in this embodiment

[0068] As Figure 5 shown, taking a sensor with one LED component and two PD components on the same FPC board as an example, see Figures 6 - 8As shown in the figure, determine the installation areas of the LED component and the PD component on the FPC board: the LED area and the PD area (the remaining area of the FPC board is called the fixed area). Taking the installation of the LED component as an example: Cut three sides of the LED area on the FPC board, and use the other side as the FPC folding edge. Bend the cut FPC board upward along the FPC folding edge to form a bent connection edge (also called the folding area in the figure) and an installation board (also called the lower layer area in the figure). Among them, the installation board is parallel to the FPC fixed area, and the FPC bent connection edge is inclined and used to connect the FPC board and the installation board. Utilize the flexibility of the FPC to sink the installation board. The installation board remains flat, and only the FPC bent connection edge deforms. In order to ensure the standardization of the FPC bent connection and the consistency of the sinking depth, a special shaping fixture can be designed to achieve this.

[0069] The LED component is arranged at the center of the installation board. The height of the installation board is equivalent to the thickness of the LED component or the PD component. When the FPC board is attached to the skin of the person to be measured, the LED component or the PD component on the installation board is in direct contact with the skin.

[0070] However, as shown in Figure 10 the figure, for both the LED component and the PD component, in this scheme, after the component is installed, the installation board will sink under the action of gravity and have a position offset in one direction compared with before sinking. And the calculation formula for the measurement of tissue oxygen is position-sensitive. Therefore, the position offset caused by the sinking must be calculable, and the position offset should be compensated into the tissue oxygen calculation formula to eliminate the measurement error caused by the position change of the LED and PD components.

[0071] As shown in Figure 11 the figure, the specific calculation method is as follows: A rectangular coordinate system can be established in the side view for calculating the offset. Take the center point of the LED component or the PD component before the installation board is folded as point a, and the center point of the LED component or the PD component after the installation board is folded as point b. Through equivalent translation, translate the center points a and b to the intersection point of the FPC board and the bent connection edge as the origin, and in the coordinate where the plane of the FPC board is the X-axis. Among them, b is translated to the intersection point b' of the installation board and the bent connection edge, and a is translated to the corresponding point a' on the X-axis.

[0072] According to the design structure of the sensor and the measurement principle of tissue oxygen, it is required that the LED center offset, that is, the displacement that affects the blood oxygen measurement, only needs to calculate the distance between point a and point b in the X direction, that is, the distance between point a' and point b' along the X direction, which is the length of the line segment ca' (point c is the projection of point b' on the X-axis). Among them, point c is the projection of point b' on the X-axis; the angle of ∠b'Oa' is α; the height of the component, that is, the length of the line segment b'c, is the thickness h of the corresponding component.

[0073] In the XOY coordinate system of the figure, the angle of ∠b’Oa’ is set according to the design requirements and is a known quantity. It is usually set between 45 - 60°, for example, 45°. If the angle of ∠b’Oa’ is too small, Ob’ will be relatively long, increasing the usage area; if the angle is too large, the local bending of the FPC will be severe and it is easy to break. The height of the LED, that is, the length of the line segment b’c, is determined according to the actual height of the component and is a known quantity. Therefore, the length calculation formula for the X-axis offset ca’ of the LED can be derived:

[0074] Let the height of the LED be h and ∠b’Oa’ = α, then

[0075]

[0076] Therefore, according to the height of the LED and the angle of ∠b’Oa’, the offset of the LED can be calculated, and this offset can be brought into the tissue oxygen calculation formula as a compensation parameter.

[0077] Since the PD signal obtained by the sensor is very weak, certain anti-interference measures are required to shield the useless signals as much as possible. The commonly used anti-interference technologies are described in the above closest technical solution. In order to better obtain the useful signals and shield the interference, the present invention adopts a new anti-interference measure.

[0078] As Figure 12 shown, the measurement of tissue oxygen needs to be attached to the human skin. Since the human body is a good conductor, when the sensor is attached to the skin, the sensor end will be coupled to a very strong interference signal from the human body. This is also a problem that such products will encounter and is the strongest part of various interference signals. As long as this part of the interference is properly processed, the blood oxygen signal obtained by the PD will be guaranteed.

[0079] The structure of the sensor is as Figure 13 and Figure 17 shown. There is 1 LED area and 2 PD areas in the middle three parts, and the rest of the blank area is a large-area copper foil, which is designed as a reference signal plane.

[0080] When the sensor is attached to the human skin, due to the relatively close distance, the PD area of the sensor will have a capacitive effect with the human tissue, forming a parasitic capacitance (C2); similarly, the reference signal plane will also have a parasitic capacitance (C1) with the human tissue. As Figure 14 shown, due to the existence of C2, various electromagnetic interference signals induced by the human body are coupled into the PD signal to form interference.

[0081] According to the above analysis, if the interference signal sensed by C2 to PD can be eliminated, the purpose of anti-interference can be achieved. The method used in the present invention is to obtain the interference signal through a reference signal plane and a parasitic capacitance C1, process it, and then superimpose it on the PD signal, so as to achieve the purpose of eliminating the interference of coupling C2.

[0082] The circuit topology of the sensor is as Figure 15 shown. The parasitic capacitance C2 is connected in parallel with PD, and the formed tissue oxygen PD signal enters the tissue oxygen calculation module through the first signal preconditioner, adder and ADC (A / D signal converter); the parasitic capacitance C1 is grounded through the resistor R, and the formed reference signal enters the tissue oxygen calculation module through the second signal preconditioner, inverter, adder and ADC (A / D signal converter). Among them, the first signal preconditioner and the second signal preconditioner are signal processing circuits composed of operational amplifiers, and the first signal preconditioner, the second signal preconditioner, the inverter, the adder and the ADC constitute an anti-interference circuit.

[0083] In practical applications, the anti-interference circuit can be set outside the sensor, for example, on the sensor socket.

[0084] The interference signal generated by the human body enters the sensor circuit through the parasitic capacitance C1 and the parasitic capacitance C2. Among them, the interference signal of the reference signal plane (from the parasitic capacitance C1) is sent to the inverter after passing through the second signal preconditioner; the interference signal superimposed and coupled in the tissue oxygen PD signal (from the parasitic capacitance C2) is added to the output signal of the inverter after passing through the first signal preconditioner. Among them, the main functions of the first signal conditioner and the second signal preconditioner include impedance transformation, filtering, gain transformation, IV transformation, phase adjustment, etc. The inverter can reverse the positive and negative polarities of the signal. Therefore, after the interference signal output by the inverter is added to the interference signal superimposed in the PD signal, they cancel each other out to zero, thus achieving the purpose of eliminating the interference signal.

[0085] To better illustrate the interference elimination principle, Figure 16 the superposition and elimination of sine wave signals are described in more detail. As can be seen from the figure, the PD signal superimposed with the interference signal is a quasi-sine wave with a large number of sawtooth shapes, indicating the existence of a large number of interference signals, while the PD signal after eliminating the interference is a smooth sine wave, indicating that after adding the anti-interference circuit in the present invention, a more accurate signal can be obtained; in the present invention, the noise signal is preprocessed to form a signal that cancels out the parasitic capacitance C2, and is superimposed on the tissue oxygen PD signal. After canceling out the interference signal of the parasitic capacitance C2, a more accurate signal is obtained.

[0086] It should be noted that, Figure 16The use of sine waves with different frequencies to represent the blood oxygen PD signal and the interference signal in [the text] is only for the convenience of explaining the problem. In fact, the actual PD signal and the interference signal are not necessarily sine waves and can be any waveform known in the art.

[0087] The specific embodiments of the present invention have been exemplarily described above through examples. However, the protection scope of the present invention is not limited to the above exemplary embodiments. Any modifications, equivalent replacements, improvements, etc. made by those skilled in the art within the spirit and principle of the present invention shall be included within the protection scope of the claims of the present invention.

Claims

1. A sensor with anti-interference performance, the sensor includes an FPC board, characterized in that, The FPC board is provided with a plurality of installation areas for installing LED components and PD components. Different installation areas are independent of each other. The installation areas are formed by cutting and bending the substrate at corresponding positions. The installation area includes a bent connecting edge and an installation plate. The installation plate is connected to the substrate through the bent connecting edge. The installation plate is parallel to the substrate, and the height of the installation plate is equivalent to the thickness of the corresponding LED component or PD component. After installing the LED component or PD component at the bottom of the installation plate, the bottom of the LED component or PD component is flush with the substrate.

2. The sensor with anti-interference performance according to claim 1, characterized in that, On the non-installation area of the substrate, a conductive film is provided on the surface in contact with the skin, and the conductive film is used to form a reference signal plane. Preferably, the conductive film is a conductive adhesive layer and / or a metal layer.

3. The sensor with anti-interference performance according to claim 1, characterized in that, The installation area is rectangular or other structures. The C-shaped groove is formed by cutting the installation area and retaining at least a part of the area connected to the FPC board, and bending along the connected edge to form the C-shaped groove. For example, the installation area of the LED is rectangular. Three sides of the LED installation area on the FPC are cut, and the other side is used as the folding edge. The cut FPC is bent upward along the folding edge to form a horizontal installation plate (sinking area) and a bent connecting edge. Among them, the installation plate is parallel to the FPC board, and the bent connecting edge is inclined to connect the installation plate and the FPC board. The flexibility of the FPC board is used to sink the installation plate. The LED component is arranged at the center of the installation plate. When the FPC is attached to the skin of the subject to be measured, the LED component is in direct contact with the skin.

4. The sensor with anti-interference performance according to any one of claims 1-3, characterized in that The sensor further includes a tissue oxygen calculation module. The sensor is electrically connected to the tissue oxygen calculation module. The tissue oxygen calculation module is used to receive the signals collected by the sensor and calculate the signals to obtain corresponding data.

5. The sensor with anti-interference performance according to claim 4, characterized in that, The PD component, the conductive film and the tissue oxygen calculation module are electrically connected. The PD component generates a capacitance effect with the human tissue to form a parasitic capacitance C2; the conductive film generates a parasitic capacitance C1 with the human tissue.

6. The sensor with anti-interference performance according to claim 4, characterized in that, The sensor further includes an anti-interference circuit. The PD component and the conductive film are electrically connected to the tissue oxygen calculation module through the anti-interference circuit. The anti-interference circuit is used to cancel out the interference signal of the parasitic capacitance C1 generated by the human tissue with the signal superimposed by the PD component and the parasitic capacitance C2 to obtain a denoised signal, and then transmit it to the tissue oxygen calculation module. Preferably, the anti-interference circuit includes a first signal pre-conditioner, a second signal pre-conditioner, an inverter and an ADC. The parasitic capacitance C2 is connected in parallel with the PD, and the formed tissue oxygen PD signal enters the tissue oxygen calculation module after passing through the first signal pre-conditioner and the ADC; the parasitic capacitance C1 is grounded through a resistor R, and the formed reference signal enters the tissue oxygen calculation module after passing through the second signal pre-conditioner, the inverter and the ADC.

7. The sensor with anti-interference performance according to claim 4, characterized in that, The tissue oxygen calculation module includes a calibration unit, and the calibration unit is used to calibrate the installation errors of the LED component and the PD component. The installation error is the difference between the theoretical installation position of the LED component and the PD component in the corresponding installation area and the actual position in the sinking area.

8. The sensor with anti-interference performance according to claim 7, wherein The calculation method of the installation error includes the following steps: S1. Take the center point of the LED component or PD component before the mounting plate is folded as point a, and the center point of the LED component or PD component after folding as point b. Through equivalent translation, translate the center point a and the center point b to the intersection point of the FPC board and the bent connecting edge as the origin, and in the coordinate system with the plane where the FPC board is located as the X-axis. Among them, b is translated to the intersection point b' of the mounting plate and the bent connecting edge, and a is translated to the corresponding point a' on the X-axis; S2. Calculate the length of the line segment ca', where the c point is the projection of the b' point on the X-axis; the angle of ∠b'Oa' is α; the height of the component, that is, the length of the line segment b'c, is the thickness h of the corresponding component. The length calculation formula of the X-axis offset amount ca' of the component is as follows:

9. A method for preparing a sensor with anti-interference performance according to any one of claims 1-8, characterized in that, The steps are as follows: Determine the installation area on the substrate, cut and bend the substrate corresponding to the installation area to form the installation area. The installation area includes a bent connecting edge and a mounting plate. The mounting plate is used to mount the corresponding LED component or PD component, and the height of the mounting plate is equivalent to the thickness of the corresponding LED component or PD component.

10. Application of the sensor with anti-interference performance according to any one of claims 1-8 in near-infrared signal acquisition, such as for the measurement of blood oxygen concentration, finger pulse oxygen, tissue oxygen measurement, and determination of hemoglobin concentration.

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