Implantable pressure sensor with flexible corrugated diaphragm and its fabrication method

Abstract

This invention relates to the field of implantable pressure sensors, and discloses an implantable pressure sensor with a flexible corrugated diaphragm and its manufacturing method, comprising: a corrugated diaphragm, a pressure-sensing diaphragm, and a supporting base; the corrugated diaphragm is disposed on the upper side of the pressure-sensing diaphragm; the pressure-sensing diaphragm is disposed on the upper side of the supporting base, and a pressure-sensing cavity is provided between the two; the corrugated diaphragm includes an integrally formed corrugated portion and a flat portion; the corrugated portion is the pressure-sensing portion, used to sense external pressure and transmit the pressure to the flat portion; the cross-sectional curve of the corrugated portion is a periodic curve; the flat portion is a joint portion, which is attached to the upper side of the pressure-sensing diaphragm and transmits pressure thereto. The implantable pressure sensor with a flexible corrugated diaphragm effectively alleviates the fatigue fracture problem caused by stress concentration by attaching a flexible corrugated diaphragm to the upper side of the pressure-sensing diaphragm. The special structure of the corrugated diaphragm enables a more uniform stress distribution, thereby extending the service life of the sensor.

Description

Technical Field

[0001] This invention relates to the field of implantable pressure sensors, and in particular to implantable pressure sensors with flexible corrugated diaphragms. Background Technology

[0002] Implantable pressure sensors have significant applications in the medical field, particularly in cardiovascular disease monitoring and intracranial pressure monitoring. By measuring changes in intracellular pressure in real time and accurately, these sensors provide crucial data support for disease diagnosis, treatment, and rehabilitation. However, most existing implantable pressure sensors employ a capacitive cavity pressure sensor structure, and their core component, the pressure-sensing diaphragm, suffers from numerous problems under dynamic pressure, limiting their performance and lifespan.

[0003] Implantable pressure sensors detect pressure through a pressure-sensing diaphragm. When dynamic pressure is applied to the diaphragm, it undergoes elastic deformation. However, stress concentration is prone to occur at the center and connection points of the diaphragm. This stress concentration can lead to fatigue fracture of the diaphragm during long-term use, especially under cyclic dynamic loads (such as the cyclic contraction of blood vessel walls), where the risk of fatigue fracture increases significantly. Once fatigue fracture occurs, it not only causes sensor failure, preventing normal pressure monitoring, but may also lead to serious safety accidents such as implant rupture and tissue damage. The thickness of the pressure-sensing diaphragm directly affects its sensitivity and mechanical strength. Generally, the thinner the diaphragm, the greater its deformation under the same pressure, resulting in higher sensitivity. However, reducing the diaphragm thickness also leads to a significant decrease in its mechanical strength. Therefore, there is an irreconcilable contradiction between sensitivity and mechanical strength in existing implantable pressure sensors, making it difficult to simultaneously achieve high sensitivity and high reliability. Summary of the Invention

[0004] To address the aforementioned technical problems, the present invention provides an implantable pressure sensor with a flexible corrugated diaphragm, comprising: a corrugated diaphragm, a pressure-sensing diaphragm, and a support base; the corrugated diaphragm is disposed on the upper side of the pressure-sensing diaphragm; the pressure-sensing diaphragm is disposed on the upper side of the support base, and a pressure-sensing cavity is provided between the two; The corrugated diaphragm includes an integrally formed corrugated portion and a flat portion; the corrugated portion is a pressure-sensing portion, used to sense external pressure and transmit the pressure to the flat portion; the cross-sectional curve of the corrugated portion is a periodic curve; the flat portion is a joint portion, which is attached to the upper side of the pressure-sensing diaphragm and transmits pressure to it.

[0005] Optionally, an upper electrode is provided on the lower side of the pressure-sensing diaphragm, a lower electrode is provided on the lower side of the pressure-sensing cavity, and a lead hole communicating with the interior of the pressure-sensing cavity is provided on the lower side of the support base.

[0006] Optionally, the corrugated diaphragm is made of silicone, PDMS, hydrogel, or parylene-C.

[0007] Optionally, the pressure-sensitive diaphragm is made of monocrystalline silicon or stainless steel.

[0008] Optionally, the support base is made of SiO2, BF33, or Pyrex glass.

[0009] Optionally, the periodic curve is a sine curve, a periodic triangular wave, or a periodic rectangular wave.

[0010] Optionally, the corrugations of the corrugated diaphragm are concentric corrugated rings that diffuse from the inside out, or parallel corrugations that extend in one direction.

[0011] Optionally, the outer contour of the corrugated diaphragm matches the outer contour of the pressure-sensing diaphragm; the corrugated diaphragm is located directly above the pressure-sensing cavity; and the projected area of ​​the corrugated diaphragm is larger than the projected area of ​​the pressure-sensing cavity.

[0012] A method for fabricating an implantable pressure sensor with a flexible corrugated diaphragm, applicable to the aforementioned implantable pressure sensor with a flexible corrugated diaphragm, comprising: Step 1: The corrugated diaphragm is made of PDMS material and prepared by a mold method; the mold is prepared using micro-nano fabrication technology according to preset parameters; the PDMS solution is prepared and degassed under vacuum, the degassed liquid is spin-coated onto the surface of the mold, and then the mold is placed in a vacuum oven to cure and form a corrugated diaphragm of a specified thickness. Step 2: Bond the pressure-sensitive diaphragm and the support base together; Step 3: Clean the corrugated diaphragm and the pressure-sensitive diaphragm. Perform low-temperature plasma treatment on the bonding surfaces of the corrugated diaphragm and the pressure-sensitive diaphragm to activate the surfaces and enhance the bonding strength of the interface. Step 4: Adhere the flat side of the corrugated diaphragm to the pressure-sensitive diaphragm.

[0013] Optionally, before step 2, electrodes may be disposed on the lower side of the pressure-sensitive diaphragm and the lower side of the pressure-sensitive cavity.

[0014] Compared with the prior art, the present invention achieves the following technical effects: An implantable pressure sensor with a flexible corrugated diaphragm effectively mitigates fatigue fracture caused by stress concentration by attaching the flexible corrugated diaphragm to the upper side of the pressure-sensing diaphragm. The special structure of the corrugated diaphragm enables more uniform stress distribution, thereby extending the sensor's service life. Simultaneously, the corrugated diaphragm isolates the pressure-sensing diaphragm from the influence of external media, protecting it from corrosion and wear. The corrugated diaphragm effectively transmits pressure signals, making the deformation curve of the pressure-sensing diaphragm more linear, thus improving the sensor's accuracy. This invention improves the sensor's mechanical strength and fatigue resistance while maintaining sensitivity. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of an implantable pressure sensor with a flexible corrugated diaphragm according to an embodiment of the present invention. Figure 2 This is an exploded structural diagram of an implantable pressure sensor with a flexible corrugated diaphragm according to an embodiment of the present invention. Figure 3 This is a cross-sectional schematic diagram of the corrugated diaphragm in an implantable pressure sensor with a flexible corrugated diaphragm according to an embodiment of the present invention. Figure 4 Stress distribution diagram of an implantable pressure sensor with a flexible corrugated diaphragm before being attached to the corrugated diaphragm, according to an embodiment of the present invention. Figure 5 Stress distribution diagram of an implantable pressure sensor with a flexible corrugated diaphragm after being attached to the corrugated diaphragm, according to an embodiment of the present invention. Figure 6 Stress distribution diagram of an implantable pressure sensor with a flexible corrugated diaphragm after being attached to a first optimized corrugated diaphragm, according to an embodiment of the present invention. Figure 7 Stress distribution diagram of an implantable pressure sensor with a flexible corrugated diaphragm after being attached to a second optimized corrugated diaphragm, according to an embodiment of the present invention. Figure 8 The graph shows a comparison of the CP curves of four models of an implantable pressure sensor with a flexible corrugated diaphragm provided in an embodiment of the present invention.

[0016] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0017] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0018] like Figures 1-8As shown, an embodiment of the present invention provides an implantable pressure sensor with a flexible corrugated diaphragm, comprising: a corrugated diaphragm 1, a pressure-sensing diaphragm 2, and a support base 3; the corrugated diaphragm 1 is disposed on the upper side of the pressure-sensing diaphragm 2; the pressure-sensing diaphragm 2 is disposed on the upper side of the support base 3, and a pressure-sensing cavity 4 is disposed between the two. The corrugated diaphragm 1 includes an integrally formed corrugated portion 11 and a flat portion 12; the corrugated portion 11 is a pressure-sensing portion, used to sense external pressure and transmit the pressure to the flat portion 12; the cross-sectional curve of the corrugated portion 11 is a periodic curve; the flat portion 12 is a joint portion, which is attached to the upper side of the pressure-sensing diaphragm and transmits pressure to it.

[0019] Optionally, an upper electrode is provided on the lower side of the pressure-sensing diaphragm 2, a lower electrode is provided on the lower side of the pressure-sensing cavity 4, and a lead hole communicating with the interior of the pressure-sensing cavity is provided on the lower side of the support base 3.

[0020] Optionally, the corrugated diaphragm 1 may be made of materials such as silicone, PDMS, hydrogel, or parylene-C.

[0021] Optionally, the pressure-sensitive diaphragm 2 may be made of monocrystalline silicon, stainless steel, or the like.

[0022] Optionally, the support base 3 may be made of materials such as SiO2, BF33, or Pyrex glass.

[0023] Optionally, the pressure-sensitive diaphragm 2 and the support base 3 are entities with the same external outline, including circles, rectangles, polygons, etc.

[0024] Optionally, the periodic curve may be a sine curve, a periodic triangular wave, a periodic rectangular wave, etc.

[0025] Optionally, the corrugations of the corrugated diaphragm 1 are concentric corrugated rings (circular, elliptical, rectangular, etc.) that diffuse from the inside out, or parallel corrugations that extend in one direction.

[0026] Optionally, the outer contour of the corrugated diaphragm 1 matches the outer contour of the pressure-sensing diaphragm 2; the corrugated diaphragm 1 is located directly above the pressure-sensing cavity 4; and the projected area of ​​the corrugated diaphragm 1 is larger than the projected area of ​​the pressure-sensing cavity 4.

[0027] Optionally, the thickness of the corrugated portion 11 is 25μm-200μm, and the thickness of the flat portion 12 is 10-50μm.

[0028] Optionally, the thickness of the pressure-sensitive diaphragm 2 is 5-100 μm and the diameter is 1000-2000 μm; the thickness of the support base 3 is 300-600 μm and the diameter is 1000-2000 μm; and the height of the pressure-sensitive cavity 4 is 5-100 μm and the diameter is 800-1600 μm.

[0029] Example 1: In this embodiment, as Figure 3 As shown, the periodic curve is a sine curve, and the corrugations are concentric corrugated rings that diffuse from the inside out. The thickness of the corrugated portion 11 is a (the distance between the crest and trough), the wave pitch is b (the distance between two crests / troughs), and the thickness of the flat portion is h. In this embodiment, a=b=3h, and the thickness of the pressure-sensitive diaphragm is a.

[0030] Figures 4-5 The stress distribution of the pressure-sensitive diaphragm 2 before and after the corrugated diaphragm 1 is attached is shown. Figure 4 As shown, before the corrugated diaphragm 1 is attached, the stress is mainly concentrated in the middle of the pressure-sensitive diaphragm 2 and at the junction of the pressure-sensitive diaphragm 2 and the support base 3. Figure 5 As shown, after attaching the corrugated diaphragm 1, the stress at the junction of the pressure-sensitive diaphragm 2 and the support base 3 is significantly reduced, and the stress distribution in the middle of the pressure-sensitive diaphragm 2 is also improved.

[0031] Example 2: The structure of the corrugated diaphragm is optimized using methods such as finite element analysis. In this embodiment, the corrugated diaphragm adopts the first optimized corrugated diaphragm, such as... Figure 6 As shown, the periodic curve is a sine curve, and the ripples are concentric corrugated rings spreading outwards; concentric arrays of annular grooves are provided on the flat portion, with a depth of h and a width of h / 2; each annular groove is located directly below each wave crest. In this embodiment, a=b=3h, and the thickness of the pressure-sensitive diaphragm is a.

[0032] like Figure 6 As shown, after attaching the corrugated diaphragm 1 with the annular groove, the stress distribution in the middle of the pressure-sensitive diaphragm 2 and the stress distribution at the junction of the pressure-sensitive diaphragm 2 and the support base 3 are more uniform than the stress distribution when attaching the corrugated diaphragm 1 in Example 1. This helps to improve the linearity of the pressure sensor and eliminate high stress points to improve the damage threshold.

[0033] Example 3: The structure of the corrugated diaphragm is optimized using methods such as finite element analysis. In this embodiment, the corrugated diaphragm adopts a second optimized corrugated diaphragm, such as... Figure 7As shown, the periodic curve is a sine curve; the corrugations are concentric corrugated rings spreading outwards, distributed as follows: three low peaks are set in the middle, and then distributed outwards in a cyclical pattern of two sets of high peaks and two sets of low peaks; wherein, the corrugation thickness of the high peaks is 'a', and the corrugation thickness of the low peaks is 1 / 3a. In this embodiment, a=b=3h, and the thickness of the pressure-sensitive diaphragm is 'a'.

[0034] like Figure 7 As shown, after attaching the corrugated diaphragm 1 in Example 4, the stress distribution in the middle of the pressure-sensing diaphragm 2 and the stress distribution at the junction of the pressure-sensing diaphragm 2 and the support base 3 are more uniform than the stress distribution when attaching the corrugated diaphragm 1 in Example 1. This helps to improve the linearity of the pressure sensor and eliminate high stress points to improve the damage threshold.

[0035] In Examples 1-3, the corrugated diaphragm 1 is made of PDMS and is subjected to the same stress conditions (i.e., the externally applied pressure / intensity is the same). Figure 8 The diagram shows a comparison of the CP (capacitance-pressure) curves for the four models in Examples 1-3. Within the pressure range of 10-30 kPa, the unattached corrugated diaphragm exhibits the highest capacitive sensitivity but the worst linearity. After attaching the corrugated diaphragm, the capacitive sensitivity of the pressure sensor decreases slightly, but the linearity improves. Attaching the first and second optimized corrugated diaphragms improves both the linearity of capacitance change and the sensing sensitivity within the 10-30 kPa pressure range. The corrugated diaphragm 1 effectively alleviates fatigue fracture caused by stress concentration. Attached to the upper side of the pressure-sensing diaphragm 2, the corrugated diaphragm 1 isolates the pressure-sensing diaphragm from the influence of the external medium and effectively transmits the pressure signal, making the deformation curve of the pressure-sensing diaphragm more linear and thus improving the accuracy of the sensor.

[0036] Example 4: A method for fabricating an implantable pressure sensor with a flexible corrugated diaphragm includes: Step 1: Taking PDMS material as an example, a corrugated film 1 is prepared using a mold method; a mold is prepared using micro-nano fabrication technology according to preset parameters; a PDMS solution (Dow Corning, matrix: curing agent = 10:1) is prepared and degassed under vacuum; the degassed liquid is spin-coated onto the surface of the mold; and then the mold is placed in a vacuum oven to cure and form a corrugated film of a specified thickness. Step 2: Bond the pressure-sensitive diaphragm 2 and the support base 3 together; Step 3: Clean the corrugated diaphragm 1 and the pressure-sensitive diaphragm 2. Perform low-temperature plasma treatment on the bonding surfaces of the corrugated diaphragm 1 and the pressure-sensitive diaphragm 2 to activate the surfaces and enhance the bonding strength of the interface. Step 4: Attach the flat surface of the corrugated diaphragm to the pressure-sensitive diaphragm 2.

[0037] Optionally, the micro-nano fabrication technology in step 1 is photolithography or etching.

[0038] Optionally, the material of the mold in step 1 is silicon, silicon oxide, etc.

[0039] Optionally, before step 2, electrodes may be provided on the lower side of the pressure-sensitive diaphragm 2 and the lower side of the pressure-sensitive cavity 4.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. An implantable pressure sensor with a flexible corrugated diaphragm, characterized in that, include: A corrugated diaphragm, a pressure-sensitive diaphragm, and a supporting base; the corrugated diaphragm is disposed on the upper side of the pressure-sensitive diaphragm; the pressure-sensitive diaphragm is disposed on the upper side of the supporting base, and a pressure-sensitive cavity is provided between the two; The corrugated diaphragm includes an integrally formed corrugated portion and a flat portion; the corrugated portion is a pressure-sensing portion, used to sense external pressure and transmit the pressure to the flat portion; the cross-sectional curve of the corrugated portion is a periodic curve; the flat portion is a joint portion, which is attached to the upper side of the pressure-sensing diaphragm and transmits pressure to it.

2. The implantable pressure sensor as described in claim 1, characterized in that, in, An upper electrode is provided on the lower side of the pressure-sensitive diaphragm, a lower electrode is provided on the lower side of the pressure-sensitive cavity, and a lead hole communicating with the interior of the pressure-sensitive cavity is provided on the lower side of the support base.

3. The implantable pressure sensor as described in claim 1, characterized in that, in, The corrugated diaphragm is made of silicone, PDMS, hydrogel, or parylene-C.

4. The implantable pressure sensor as described in claim 1, characterized in that, in, The pressure-sensitive diaphragm is made of monocrystalline silicon or stainless steel.

5. The implantable pressure sensor as described in claim 1, characterized in that, in, The support base is made of SiO2, BF33, or Pyrex glass.

6. The implantable pressure sensor as described in claim 1, characterized in that, in, The periodic curve is a sine curve, a periodic triangular wave, or a periodic rectangular wave.

7. The implantable pressure sensor as described in claim 1, characterized in that, in, The corrugations of the diaphragm are concentric corrugated rings that diffuse from the inside out, or parallel corrugations that extend in one direction.

8. The implantable pressure sensor as described in claim 1, characterized in that, in, The outer contour of the corrugated diaphragm matches the outer contour of the pressure-sensing diaphragm; the corrugated diaphragm is located directly above the pressure-sensing cavity; the projected area of ​​the corrugated diaphragm is larger than the projected area of ​​the pressure-sensing cavity.

9. A method for manufacturing an implantable pressure sensor with a flexible corrugated diaphragm, applicable to the implantable pressure sensor with a flexible corrugated diaphragm according to any one of claims 1-8, characterized in that, include: Step 1: The corrugated diaphragm is made of PDMS material and prepared using a mold method; The mold was fabricated using micro-nano fabrication technology according to preset parameters; Prepare a PDMS solution and degas it under vacuum. Spin-coat the degassed liquid onto the surface of the mold. Then place the mold in a vacuum oven to cure and form a corrugated film of a specified thickness. Step 2: Bond the pressure-sensitive diaphragm and the support base together; Step 3: Clean the corrugated diaphragm and the pressure-sensitive diaphragm. Perform low-temperature plasma treatment on the bonding surfaces of the corrugated diaphragm and the pressure-sensitive diaphragm to activate the surfaces and enhance the bonding strength of the interface. Step 4: Adhere the flat side of the corrugated diaphragm to the pressure-sensitive diaphragm.

10. The method for manufacturing an implantable pressure sensor with a flexible corrugated diaphragm as described in claim 9, characterized in that, in, Before step 2, electrodes are also provided on the lower side of the pressure-sensitive diaphragm and the lower side of the pressure-sensitive cavity.

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