A flexible pressure sensing device and a method of manufacturing the same

Abstract

A flexible pressure sensing device and its fabrication method are disclosed, relating to the field of medical wearable device technology. The flexible pressure sensing device includes a substrate and a sensing unit connected to the substrate. The substrate includes a first component and a second component arranged adjacent to each other. The first component is configured to generate a first deformation acting on the sensing unit when subjected to positive pressure, and the second component is configured to generate a second deformation acting on the sensing unit when subjected to shear force. The sensing unit is configured to output a first signal corresponding to the positive pressure based on the first deformation, and to output a second signal corresponding to the shear force based on the second deformation. It can simultaneously detect positive pressure and shear force, and has a simple overall structure, which is beneficial to improving applicability.

Description

Technical Field

[0001] This invention relates to the field of medical wearable device technology, and in particular to a flexible pressure sensing device and its preparation method. Background Technology

[0002] Wearable medical devices refer to portable medical or health electronic devices that can be worn directly on the body. Their main function is to sense and record data such as the body's physical condition, metabolism, and changes in body shape. For example, they can monitor human health indicators such as blood sugar, blood pressure, and heart rate. Accurate sensing is the key to the reliability of wearable medical devices.

[0003] Shear force refers to the progressive parallel sliding force applied to the surfaces of adjacent objects, causing them to slide in opposite directions. It acts on the deep layers of the skin, causing relative tissue displacement and cutting off blood supply to a large area. Therefore, detecting shear force is also crucial for understanding the body's condition. Wearable medical devices need to use flexible pressure sensors to sense pressure. Existing flexible pressure sensors can usually only sense positive pressure but cannot detect shear force, which has certain limitations. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a flexible pressure sensing device and its preparation method, which can simultaneously measure normal pressure and shear force, has a simple structure, and is easy to prepare.

[0005] The present invention provides a flexible pressure sensing device, including a substrate and a sensing unit connected to the substrate. The substrate includes a first component and a second component disposed adjacent to each other. The first component is configured to generate a first deformation acting on the sensing unit when subjected to a normal pressure, and the second component is configured to generate a second deformation acting on the sensing unit when subjected to a shear force. The sensing unit is configured to output a first signal corresponding to the normal pressure based on the first deformation, and to output a second signal corresponding to the shear force based on the second deformation.

[0006] The substrate supports and arranges the sensing unit, and generates a deformation output based on external normal pressure F and shear force F, enabling the sensing unit to detect the normal pressure F and shear force F. The substrate is configured to include adjacent first and second components. When subjected to normal pressure, the first component generates a first deformation, which acts on the sensing unit. The sensing unit outputs a first signal based on the first deformation, which characterizes the magnitude of the normal pressure, thus enabling the measurement of the normal pressure. The second component generates a second deformation, which acts on the sensing unit. The sensing unit outputs a second signal based on the second deformation, which characterizes the magnitude of the shear force, thus enabling the measurement of the shear force. This design features high integration and a small overall size, which facilitates wider application.

[0007] In one embodiment, the first component is connected to the upper end of the second component, and the first component is configured such that its elastic modulus is less than that of the second component, so that the upper end of the first component is more easily deformed than the second component when subjected to the normal pressure.

[0008] In one embodiment, the sensing unit includes a first sensing chip and a second sensing chip. The first sensing chip is disposed between the first component and the second component to be responsive to the first deformation, and the second sensing chip is disposed on the side of the second component to be responsive to the second deformation.

[0009] In one embodiment, the first sensing chip includes a response structure located near the first component. The response structure includes four resistors that form a Wheatstone bridge. The first deformation can act on the response structure to cause a change in resistance, thereby outputting the first signal.

[0010] In one embodiment, the end of the response structure opposite to the first component is provided with a control layer, the control layer being configured to have at least one weak region so that the response structure is easily deformed under the action of the first deformation.

[0011] In one embodiment, the second sensing chip includes a response structure located on the side opposite to the second component. The response structure includes four resistors that form a Wheatstone bridge. The second deformation can act on the response structure to cause a change in the resistance of the response structure, thereby outputting the second signal.

[0012] In one embodiment, the response structure has a control layer at one end near the second component, the control layer being configured to have at least one weak region so that the response structure is easily deformed under the action of the second deformation.

[0013] In one embodiment, the first component adopts a frustum structure, and the second component adopts a cuboid structure.

[0014] In one embodiment, the orthographic projection of the lower end face of the first component in the vertical direction coincides with the orthographic projection of the upper end face of the second component in the vertical direction.

[0015] The present invention also proposes a method for fabricating a flexible pressure sensing device, which includes the following steps: Substrate preparation: Prepare a first component and a second component, wherein the elastic modulus of the first component is less than that of the second component; Fabrication of the sensing unit: Boron ion implantation is performed on the front side of the silicon wafer to form four resistors, which constitute a Wheatstone bridge. A weak region is set on the back side of the silicon wafer to form a control layer. Connecting the substrate and the sensing unit: Connect the first sensing chip to the upper surface of the second component, connect the second sensing chip to the side of the second component, and connect the first component to the upper end of the second component.

[0016] The preparation method proposed in this invention is simple in steps and easy to operate, and can realize the measurement of normal pressure and shear force. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of an embodiment of the present invention under applied positive pressure; Figure 3 This is a schematic diagram of the structure of an embodiment of the present invention when shear force is applied; Figure 4 This is a schematic diagram of the response structure according to an embodiment of the present invention; Figure 5 This is a schematic flowchart of a preparation method according to an embodiment of the present invention.

[0019] In the picture: 100 - Flexible pressure sensing device; 10 - Substrate; 11 - First component; 12 - Second component; 20 - Sensing unit; 21 - First sensing chip; 22 - Second sensing chip; 23 - Response structure; F1 - Positive pressure; F2 - Shear force. Detailed Implementation

[0020] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. Based on the description of the present invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of the present invention.

[0021] Unless otherwise explicitly specified and limited, the terms "setup," "installation," and "connection" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of these terms based on the specific circumstances.

[0022] The terms “upper,” “lower,” “left,” “right,” “front,” “back,” “top,” “bottom,” “inner,” and “outer,” etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use. They are only for the convenience of description and simplification, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0023] The terms “first,” “second,” “third,” etc., are used merely to distinguish elements with similar properties, not to indicate or imply relative importance or a specific order.

[0024] The terms “include,” “comprising,” or any other variation thereof are intended to cover non-exclusive inclusion, which includes not only the elements listed but also other elements not expressly listed.

[0025] Wearable medical devices refer to portable medical or health electronic devices that can be worn directly on the body. Their main function is to sense and record data such as the body's physical condition, metabolism, and changes in body shape. For example, they can monitor human health indicators such as blood sugar, blood pressure, and heart rate. Accurate sensing is the key to the reliability of wearable medical devices.

[0026] Shear force refers to the progressive parallel sliding force applied to the surfaces of adjacent objects, causing them to slide in opposite directions. It acts on the deep layers of the skin, causing relative tissue displacement and cutting off blood supply to a large area. Therefore, detecting shear force is also crucial for understanding the body's condition. Wearable medical devices need to use flexible pressure sensors to sense pressure. Existing flexible pressure sensors can usually only sense positive pressure but cannot detect shear force, which has certain limitations.

[0027] Reference Figure 1 and combined Figure 2 and Figure 3 The flexible pressure sensing device 100 proposed in this invention includes a substrate 10 and a sensing unit 20 connected to the substrate 10. The substrate 10 includes a first component 11 and a second component 12. The first component 11 and the second component 12 are arranged adjacent to each other. The first component 11 is configured to generate a first deformation acting on the sensing unit 20 when subjected to a positive pressure F1. The second component 12 is configured to generate a second deformation acting on the sensing unit 20 when subjected to a shear force F2. The sensing unit 20 is configured to output a first signal corresponding to the positive pressure F1 based on the first deformation, and to output a second signal corresponding to the shear force F2 based on the second deformation.

[0028] The substrate 10 supports and arranges the sensing unit 20, and generates a deformation output acting on the sensing unit 20 based on the external positive pressure F1 and shear force F2, enabling the sensing unit 20 to detect the positive pressure F1 and shear force F2. The substrate 10 is configured to include adjacent first component 11 and second component 12. When subjected to positive pressure F1, the first component 11 generates a first deformation, which acts on the sensing unit 20. The sensing unit 20 outputs a first signal based on the first deformation, which characterizes the magnitude of the positive pressure F1, thereby achieving the measurement of the positive pressure F1. The second component 12 generates a second deformation, which acts on the sensing unit 20. The sensing unit 20 outputs a second signal based on the second deformation, which characterizes the magnitude of the shear force F2, thereby achieving the measurement of the shear force F2. This design features high integration and a small overall size, which is beneficial for expanding the range of applications.

[0029] As an optional embodiment, the first component 11 is connected to the upper end of the second component 12. The first component 11 is configured such that its elastic modulus is smaller than that of the second component 12, so that when the upper end of the first component 11 is subjected to a normal pressure F1, it is easier to deform and generate a first deformation than the second component 12. This allows the sensing unit 20 to avoid the deformation interference of the second component 12 when outputting the first signal, thereby ensuring the accuracy of the normal pressure F1 detection result and ensuring the overall detection accuracy.

[0030] In an example scheme, such as Figure 1 As shown, the first component 11 adopts a frustum structure, and the second component 12 adopts a cuboid structure. Optionally, the shape and size of the first component 11 and the second component 12 can be flexibly set according to the detection sensitivity and deformation requirements, and can also adopt columnar structures, frustum structures, etc.

[0031] In one example, the orthographic projection of the lower end face of the first component 11 in the vertical direction coincides with the orthographic projection of the upper end face of the second component 12 in the vertical direction, so as to stabilize the connection between the first component 11 and the second component 12 and to reduce the overall volume.

[0032] In one example embodiment, the first component 11 is made of PDMS (Polydimethylsiloxane) material. Optionally, the ratio of the PDMS component to the curing agent component in the first component 11 is 10:4.

[0033] In one example embodiment, the second component 12 is made of PDMS material. Optionally, the ratio of the PDMS component to the curing agent component in the second component 12 is 10:1.

[0034] In one example, the first component 11 and the second component 12 may also be made of other materials, such as resin, sponge, silicone, etc., which have the ability to transmit force and deform in response to force, depending on the requirements of detection sensitivity.

[0035] As an optional implementation method, such as Figure 1 As shown, the sensing unit 20 includes a first sensing chip 21 and a second sensing chip 22. The first sensing chip 21 is disposed between the first component 11 and the second component 12. More specifically, the first sensing chip 21 is connected to the upper end of the second component 12 so as to respond to a first deformation generated by the first component 11. The second sensing chip 22 is connected to the side of the second component 12 so as to respond to a second deformation generated by the second component 12.

[0036] For example, the first sensor chip 21 is bonded to the upper surface of the second component 12, and the second sensor chip 22 is bonded to the side surface of the second component 12.

[0037] In an example scheme, such as Figure 4 As shown, the first sensing chip 21 includes a response structure 23 located at one end close to the first component 11. The response structure 23 includes four resistors (R1, R2, R3, R4), which form a Wheatstone bridge. The first deformation of the first component 11 can act on the first sensing chip 21, causing the response structure 23 to produce a resistance change, thereby outputting a first signal.

[0038] For example, the response structure 23 has a control layer at one end away from the first component 11. The control layer is configured to have at least one weak area so that the response structure 23 is easily deformed under the action of the first deformation, thereby causing the Wheatstone bridge to lose balance. The Wheatstone bridge can output a first signal corresponding to the positive pressure F1.

[0039] Optionally, the control layer and the response structure 23 are integrally formed.

[0040] Optionally, the control layer includes at least one cavity to form a cavity structure. The cavity is configured to allow the control layer to easily deform under the action of the first deformation, thereby enabling the Wheatstone bridge to have a sensitive signal output capability. In a preferred example, the cavity is configured as a square cavity.

[0041] like Figure 2 As shown, when a positive pressure F1 is applied to the flexible pressure sensing device 100, that is, when the upper end surface of the first component 11 is subjected to a positive pressure F1 perpendicular to itself, since the elastic modulus of the first component 11 is less than that of the second component 12, the first component 11 is more prone to deformation than the second component 12 when subjected to the positive pressure F1, thereby applying a force to the first sensing chip 21. The response structure 23 bends based on the first deformation of the first component 11 and outputs a first signal proportional to the magnitude and direction of the positive pressure F1. The magnitude of the positive pressure F1 can be measured through the first signal. The elastic modulus of the second component 12 is configured such that the first component 11 hardly deforms when subjected to the positive pressure F1. This setting ensures that the second sensing chip 22 is not affected by the positive pressure F1 and the second component 12. The second sensing chip 22 has no signal output, avoiding interference from multiple signal outputs and preventing the accuracy of the detection result from being affected by signal coupling. This helps to ensure the sensitivity and accuracy of the positive pressure F1 detection.

[0042] In an example scheme, such as Figure 4 As shown, the second sensing chip 22 includes a response structure 23 located at one end away from the second component 12. The response structure 23 includes four resistors (R1, R2, R3, R4), which form a Wheatstone bridge. The second deformation of the second component 12 can act on the second sensing chip 22, causing the response structure 23 to change its resistance, thereby outputting a second signal.

[0043] For example, the response structure 23 is provided with a control layer at one end near the second component 12. The control layer is configured to have at least one weak area so that the response structure 23 is easily deformed under the action of the second deformation, thereby causing the Wheatstone bridge to lose balance and output a second signal corresponding to the shear force F2 through the Wheatstone bridge.

[0044] Optionally, the control layer and the response structure 23 are integrally formed.

[0045] Optionally, the control layer includes at least one cavity to form a cavity structure. The cavity is configured to allow the control layer to easily deform under the action of the second deformation, thereby enabling the Wheatstone bridge to have a sensitive signal output capability. In a preferred example, the cavity is configured as a square cavity.

[0046] like Figure 3 As shown, when a shear force F2 is applied to the flexible pressure sensing device 100, that is, when the side of the second component 12 is subjected to a shear force F2 perpendicular to itself, the second component 12 undergoes a second deformation to exert a force on the second sensing chip 22. During this process, the first component 12 does not act on the first sensing chip 21 due to the direction of the force. The first sensing chip 21 has no signal output or the output signal is very small, so the accuracy of the detection result will not be affected by signal coupling. The response structure 23 of the second sensing chip 22 is based on the second deformation bending deformation of the second component 12 and outputs a second signal proportional to the magnitude and direction of the shear force F2. The magnitude and direction of the shear force F2 can be measured through the second signal.

[0047] In one example, the first sensing chip 21 and the second sensing chip 22 use the same silicon-based pressure sensing chip, which has a simple structure and can make the size as small as possible while ensuring detection sensitivity. The detection principle is simple and can accurately measure the normal pressure F1 and shear force F2 without a complicated signal decoupling process.

[0048] like Figure 4 As shown, the response structure 23 includes four resistors, wherein resistor R1 and resistor R3 are arranged opposite to each other, and resistors R2 and R4 are arranged opposite to each other. The four resistors form a Wheatstone bridge. The four resistors can provide bridge power through connecting wires and output voltage signals related to the detected positive pressure F1 or shear force F2, so as to output a first signal or a second signal.

[0049] For example, the four resistors are force-sensitive resistors, formed by boron ion implantation into the surface of the force-sensitive resistor design region on the silicon wafer. Optionally, the boron ion doping concentration is... .

[0050] For example, the shear force F2 can be a positive pressure along the length or width of the second component 12.

[0051] In one embodiment, the thickness of the first sensing chip 21 and the second sensing chip 22 is 20μm or 50μm, the upper end face of the first component 11 has a size of 1mm×1mm, the lower end face has a size of 2mm×2mm, and the height is 1mm, and the size of the second component 12 is 2mm×2mm×2mm.

[0052] In another embodiment, the thickness of the first sensing chip 21 and the second sensing chip 22 is 20 μm, the upper end face of the first component 11 has a size of 2 mm × 2 mm, the lower end face has a size of 5 mm × 5 mm, and the height is 5 mm, and the size of the second component 12 is 5 mm × 5 mm × 5 mm.

[0053] By employing two ultra-thin pressure sensing chips as sensing units 20 and using a substrate 10 as the supporting structure for the two pressure sensing chips, a protective function can be achieved, improving the reliability of the pressure sensing chips. This avoids the need for simultaneous measurement of positive pressure F1 and shear force F2. The fabrication method is simple, and the overall size is small, making it suitable for complex application scenarios in medical wearable devices. The first sensing chip 21 and the second sensing chip 22 are used to measure positive pressure F1 and shear force F2, respectively, without the need for complex signal decoupling. The overall structure is simple, and the detection results are accurate.

[0054] like Figure 5 As shown, the present invention also proposes a method for manufacturing a flexible pressure sensing device 100, which specifically includes the following steps: Preparation of substrate 10: Preparation of first component 11 and second component 12, wherein the elastic modulus of first component 11 is less than the elastic modulus of second component 12; Fabrication of sensing unit 20: Boron ion implantation is performed on the front side of the silicon wafer to form four resistors, which constitute a Wheatstone bridge. A weak area is set on the back side of the silicon wafer to form a control layer. Connecting the substrate 10 and the sensing unit 20: Connect the first sensing chip 21 to the upper surface of the second component 12, connect the second sensing chip 22 to the side of the second component 12, and connect the first component 11 to the upper end of the second component 12.

[0055] As an optional embodiment, the above-described steps for preparing the substrate 10 further include: the first component 11 adopts a frustum structure, the second component 12 adopts a cuboid structure, and the orthographic projection of the lower end face of the first component 11 in the vertical direction coincides with the orthographic projection of the upper end face of the second component 12 in the vertical direction.

[0056] As an optional embodiment, the above-described steps for preparing the sensing unit 20 further include: a boron ion concentration of... .

[0057] As an optional embodiment, the above-described steps for preparing the sensing unit 20 further include: processing a cavity on the back side of the silicon wafer by etching or etching processes to form a weak area.

[0058] As an optional embodiment, the above-described steps of connecting the substrate 10 and the sensing unit 20 further include: bonding the first sensing chip 21 to the upper surface of the second component 12, and bonding the second sensing chip 22 to the side surface of the second component 12.

[0059] As an optional embodiment, the above-described steps of connecting the substrate 10 and the sensing unit 20 further include: the first sensing chip 21 is bonded to the force center position of the second component 12.

[0060] As an optional embodiment, the above-described steps of connecting the substrate 10 and the sensing unit 20 further include: the second sensing chip 22 being bonded to the force center position of the second component 12.

[0061] The preparation method proposed in this invention has simple processing steps and is easy to operate, and can realize the measurement of normal pressure F1 and shear force F2.

[0062] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A flexible pressure sensing device (100), characterized in that, The device includes a substrate (10) and a sensing unit (20) connected to the substrate (10). The substrate (10) includes a first component (11) and a second component (12) disposed adjacent to each other. The first component (11) is configured to generate a first deformation acting on the sensing unit (20) when subjected to a normal pressure (F1). The second component (12) is configured to generate a second deformation acting on the sensing unit (20) when subjected to a shear force (F2). The sensing unit (20) is configured to output a first signal corresponding to the normal pressure (F1) based on the first deformation and to output a second signal corresponding to the shear force (F2) based on the second deformation.

2. The flexible pressure sensing device (100) according to claim 1, characterized in that, The first component (11) is connected to the upper end of the second component (12). The first component (11) is configured such that its elastic modulus is less than that of the second component (12), so that the upper end of the first component (11) is more easily deformed than the second component (12) when subjected to the positive pressure (F1).

3. The flexible pressure sensing device (100) according to claim 1 or 2, characterized in that, The sensing unit (20) includes a first sensing chip (21) and a second sensing chip (22). The first sensing chip (21) is disposed between the first component (11) and the second component (12) to be responsive to the first deformation. The second sensing chip (22) is disposed on the side of the second component (12) to be responsive to the second deformation.

4. The flexible pressure sensing device (100) according to claim 3, characterized in that, The first sensing chip (21) includes a response structure (23) located on the side close to the first component (11). The response structure (23) includes four resistors that form a Wheatstone bridge. The first deformation can act on the response structure (23) to cause a change in resistance, thereby outputting the first signal.

5. The flexible pressure sensing device (100) according to claim 4, characterized in that, The response structure (23) has a control layer at one end away from the first component (11). The control layer is configured to have at least one weak area so that the response structure (23) is easily deformed under the action of the first deformation.

6. The flexible pressure sensing device (100) according to claim 3, characterized in that, The second sensing chip (22) includes a response structure (23) located on the side opposite to the second component (12). The response structure (23) includes four resistors that form a Wheatstone bridge. The second deformation can act on the response structure (23) to cause a change in resistance, thereby outputting the second signal.

7. The flexible pressure sensing device (100) according to claim 6, characterized in that, The response structure (23) has a control layer at one end near the second component (12), and the control layer is configured to have at least one weak area so that the response structure (23) is easily deformed under the action of the second deformation.

8. The flexible pressure sensing device (100) according to claim 2, characterized in that, The first component (11) adopts a frustum structure, and the second component (12) adopts a cuboid structure.

9. The flexible pressure sensing device (100) according to claim 2 or 8, characterized in that, The orthographic projection of the lower end face of the first component (11) in the vertical direction coincides with the orthographic projection of the upper end face of the second component (12) in the vertical direction.

10. A method for preparing a flexible pressure sensing device (100), characterized in that, The preparation of the flexible pressure sensing device (100) according to any one of claims 1 to 9 comprises the following steps: Preparation of substrate (10): Preparation of first component (11) and second component (12), wherein the elastic modulus of the first component (11) is less than the elastic modulus of the second component (12); Fabrication of sensing unit (20): Boron ion implantation is performed on the front side of the silicon wafer to form four resistors, which constitute a Wheatstone bridge. A weak area is set on the back side of the silicon wafer to form a control layer. Connecting the substrate (10) and the sensing unit (20): Connect the first sensing chip (21) to the upper surface of the second component (12), connect the second sensing chip (22) to the side of the second component (12), and connect the first component (11) to the upper end of the second component (12).

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