Liquid-cooled high-temperature pressure sensor and method of manufacturing the same

Abstract

The application discloses a liquid-cooled high-temperature pressure sensor and a preparation method thereof, and belongs to the technical field of micro-electro-mechanical systems and extreme environment physical quantity measurement. The liquid-cooled high-temperature pressure sensor comprises a sensor packaging main body, a micro-flow channel cooling system and a sensor chip. The sensor packaging main body comprises a sensor base and a corrugated sheet. A ceramic heat insulation ring is arranged in the sensor base. The corrugated sheet is connected with the sensor base to form a cavity. The sensor chip is fixed at the bottom of the cavity. The micro-flow channel cooling system comprises two cavity-in spiral tubes arranged in the cavity, an embedded spiral tube arranged in the inner part of the core body and a micro-flow channel integrated in the sensor chip. The lower parts of the two cavity-in spiral tubes are wrapped around the outer part of the sensor chip. The embedded spiral tube is located directly below the sensor chip. The glass packaging layer of the sensor chip is provided with the micro-flow channel. The application solves the problem that the micro environment of the pressure sensor chip cannot be effectively cooled in the prior art.

Description

Technical Field

[0001] This invention belongs to the field of micro-electro-mechanical systems (MEMS) and extreme environment physical quantity measurement technology, specifically relating to a liquid-cooled high-temperature pressure sensor and its fabrication method. Background Technology

[0002] Piezoresistive pressure sensors occupy an important position in industrial testing due to their significant engineering advantages such as high sensitivity, wide frequency response range, and compact structure. However, when placed in thermal environments exceeding 125°C, such as in aerospace engines, high-speed wind tunnel testing, and applications in metallurgy and chemical engineering, pressure sensors face severe challenges. At temperatures above 125°C, the electrical isolation of the PN junction in pressure sensor chips made of single-crystal silicon is prone to failure, leading to a surge in reverse leakage current and causing PN junction breakdown, ultimately resulting in device damage. Furthermore, temperatures exceeding 400°C can also cause high-temperature creep in pressure sensor chips made of wide-bandgap semiconductor materials, such as silicon-on-insulator (SOI), silicon carbide, and sapphire, resulting in nonlinear drift of the piezoresistive coefficient, causing severe thermal zero-point drift and sensitivity degradation. Therefore, the upper temperature limit of the pressure sensor chip is a key factor determining the upper operating temperature limit of the pressure sensor. To overcome these problems, existing technologies mostly adopt a technical approach of adding a liquid cooling structure to the outside of the sensor, mainly including remote pressure tapping cooling and additional external liquid cooling jacket cooling. In the pressure transmission process, the "cavity effect" caused by the slender pressure-sensing tubes in pressure-sensing tubes attenuates the dynamic signal, leading to dynamic frequency response distortion. Furthermore, the pressure-sensing tubes are prone to blockage in complex media measurement environments. External liquid cooling jackets, due to the thick-walled outer shell and multiple layers of media separating the cold source from the chip, have extremely high thermal resistance. This makes it impossible to remove heat from the area surrounding the pressure sensor chip in a timely manner, hindering precise temperature control of the chip's microenvironment. This high thermal resistance structure results in significant thermal hysteresis; when subjected to transient thermal shocks, external cooling cannot effectively dissipate the heat accumulated in the core of the pressure sensor chip, preventing temperature control of its microenvironment. Simultaneously, the bulky liquid cooling kit increases the size and weight of the pressure sensor, making it difficult to install in space-constrained areas of aerospace engines, severely restricting the design optimization of critical aerospace engine components. Both of these cooling methods—one cooling the pressure medium, the other applying cooling to the sensor base and transferring the cooling effect to the sensor chip—fail to achieve temperature control of the pressure sensor chip's microenvironment, limiting the measurement capabilities of high-temperature pressure sensors at high temperatures. Summary of the Invention

[0003] This invention provides a liquid-cooled high-temperature pressure sensor and its fabrication method, aiming to solve the problem that the existing technology cannot effectively cool the microenvironment of the pressure sensor chip.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] In a first aspect, the present invention provides a liquid-cooled high-temperature pressure sensor, comprising a sensor packaging body, a microfluidic cooling system, and a sensor chip;

[0006] The sensor package body includes a sensor base and a corrugated sheet. The sensor base includes a shell, a ceramic heat insulation ring and a core arranged sequentially from the outside to the inside. The corrugated sheet is connected to the shell to form a cavity, which is filled with hydraulic oil. The sensor chip is fixed at the bottom of the cavity.

[0007] The microchannel cooling system includes a first and second intracavity helical tube disposed within a cavity, an embedded helical tube disposed within a core, and microchannels disposed within a sensor chip.

[0008] The lower parts of both the first and second internal helical tubes are wrapped around the sensor chip.

[0009] The embedded helical tube is located directly below the sensor chip;

[0010] The sensor chip includes a sensing layer, a sealing layer, and a glass encapsulation layer bonded together in sequence, with microchannels provided within the glass encapsulation layer.

[0011] Furthermore, the first internal spiral tube and the second internal spiral tube are connected in parallel and arranged in an alternating double spiral structure.

[0012] Furthermore, the diameter of the upper half of the spiral tube in the first cavity is smaller than the diameter of the lower half, and the pitch of the upper half is smaller than the pitch of the lower half; the diameter of the upper half of the spiral tube in the second cavity is smaller than the diameter of the lower half, and the pitch of the upper half is smaller than the pitch of the lower half.

[0013] Furthermore, the embedded helical tube has a double helix structure with series conduction.

[0014] Furthermore, the microchannel includes a chip inlet channel, a Venturi nozzle array, and a chip outlet channel. The Venturi nozzle array includes multiple Venturi nozzles arranged circumferentially along the chip inlet channel. The constriction section of the Venturi nozzle is located near the chip inlet channel, and the expansion section of the Venturi nozzle is located near the chip outlet channel. Both the chip inlet channel and the chip outlet channel are connected to the Venturi nozzle array.

[0015] Furthermore, an annular channel is provided outside the Venturi nozzle array, and the annular channel is connected to the Venturi nozzle array. The chip liquid outlet channel is vertically arranged and is connected to the annular channel.

[0016] Furthermore, the inlets of the first inner chamber spiral tube, the second inner chamber spiral tube, the embedded spiral tube, and the microchannel are all connected to the main liquid inlet channel, and the outlets are all connected to the main liquid outlet channel. Both the main liquid inlet channel and the main liquid outlet channel are located at the bottom of the core.

[0017] Secondly, the present invention provides a method for manufacturing a liquid-cooled high-temperature pressure sensor, comprising the following steps:

[0018] Step 1: Form a piezoresistive region, an insulating layer, and a metal electrode on the front side of an insulator-on-silicon wafer;

[0019] Step 2: Process the back side of the silicon-on-insulator wafer to form a sensitive layer;

[0020] Step 3: Thin the single-crystal silicon wafer to serve as a sealing layer, and bond the sealing layer to the back of the silicon-on-insulator wafer to form a pressure cavity, thus obtaining a structure with a sensitive layer and a sealing layer.

[0021] Step 4: Microchannels are fabricated in the glass wafer and bonded to the back side of the structure with a sensitive layer and a sealing layer obtained in Step 3 to form a glass encapsulation layer. The sensor chip is obtained by dicing.

[0022] Step 5: Prepare the assembly, which includes a core, a first internal helical tube and a second internal helical tube. An embedded helical tube is pre-placed inside the core. Assemble and sinter the core with the outer shell, ceramic heat insulation ring and metal pins to obtain the sensor base.

[0023] Step 6: Attach the sensor chip to the core and connect the metal pads of the sensor chip to the metal pins using bonding wires;

[0024] Step 7: Seal the corrugated sheet with the sensor base to form a cavity, and inject hydraulic oil into the cavity to obtain a liquid-cooled high-temperature pressure sensor.

[0025] Furthermore, in step 4, a femtosecond laser is used to process microchannels inside the glass wafer.

[0026] Furthermore, in step 5, the composite is prepared by metal 3D printing in one piece.

[0027] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0028] This invention constructs a four-layer cooling system with tightly integrated components, progressing from the outside in. The ceramic heat-insulating ring utilizes the low thermal conductivity of ceramic material as the first cooling layer for the sensor chip, effectively reducing heat transfer efficiency between the outer shell and the core. The first and second internal spiral tubes serve as the second cooling layer, directly cooling the hydraulic oil and preventing it from overheating, thus cooling the contact surface between the sensor chip and the hydraulic oil—that is, cooling the upper surface and sides of the sensor chip. The embedded spiral tube, as the third cooling layer, constructs a cooling circuit within the core, directly cooling the physical contact interface between the core and the sensor chip, eliminating heat buildup at the bottom of the sensor chip, and cooling the bottom surface. The microchannel, as the final cooling layer, directly cools the interior of the sensor chip, using high-speed fluid to carry away heat, achieving active cooling of the sensor chip.

[0029] This invention embeds a microfluidic cooling system directly within the pressure sensor base and the sensor chip, achieving fully enclosed three-dimensional cooling of the sensor chip area. This enables a deep synergy between passive insulation and active cooling, allowing direct heat exchange beyond the high thermal resistance outer shell. The cooling effect of the cooling structure directly acts on the sensor chip, achieving in-situ cooling and significantly improving heat dissipation efficiency. This ensures the pressure sensor's measurement and survivability at 800℃, with a chip area temperature rise not exceeding 3℃. It enables the pressure sensor to operate stably at 800℃ and can withstand short-term temperatures up to 1200℃.

[0030] Furthermore, the first and second internal spiral tubes are arranged in a parallel, staggered configuration. On one hand, the staggered arrangement of the two spiral tubes within the limited cavity greatly increases the contact area between the coolant and the hydraulic oil, significantly improving heat transfer efficiency. On the other hand, the staggered arrangement of the first and second internal spiral tubes forms a parallel double-helix structure, avoiding the problem of excessive temperature rise at the end caused by long-distance flow in a single tube, ensuring the uniformity of the temperature field inside the cavity; at the same time, it shortens the length of a single pipe, reducing the pressure loss of the coolant along the flow path.

[0031] Furthermore, the embedded spiral tube adopts a series-connected double spiral structure, which on the one hand builds a high-density heat transfer network inside the sensor core, improving the heat conduction efficiency; on the other hand, the total length of the embedded spiral is about one-third of the total length of the spiral tube in the first cavity and the spiral tube in the second cavity, and its end temperature rise effect is relatively weak, and the processing technology is easy and occupies little space.

[0032] Furthermore, in the upper part of the first and second internal spiral tubes, a small-diameter, high-density spiral structure is adopted to build a heat shield layer at the top to intercept external heat flow; in the lower part, a large-diameter, sparse spiral structure is adopted to maintain a constant temperature at the bottom.

[0033] Furthermore, the microchannel includes a Venturi nozzle, which enhances heat transfer efficiency by utilizing the principle that the flow velocity increases when the fluid flows through the throat of the Venturi nozzle. This forms a high-speed jet inside the sensor chip, significantly improving the heat transfer efficiency inside the sensor chip and achieving active cooling of the sensor chip.

[0034] Furthermore, the first internal spiral tube, the second internal spiral tube, the embedded spiral tube, and the microchannel are connected in parallel, sharing the main inlet channel and the main outlet channel, which saves space in the liquid flow pipeline and facilitates connection to the supply pipeline and outlet pipeline.

[0035] This invention provides a method for fabricating a liquid-cooled high-temperature pressure sensor. The sensor chip is fabricated using standard MEMS technology combined with femtosecond laser processing technology. This method achieves miniaturization of the sensor chip while enabling the pressure sensor to have high-precision pressure signal measurement capabilities.

[0036] Furthermore, the core, the first intracavity helical tube, and the second intracavity helical tube can be prepared by 3D printing in one piece, which can accurately form the required structure. Moreover, the one-piece molding can improve the structural strength and sealing performance, and avoid coolant leakage. Attached Figure Description

[0037] Figure 1 A cross-sectional view of the liquid-cooled high-temperature pressure sensor provided by the present invention;

[0038] Figure 2 This is a schematic diagram of the first flow channel of the present invention;

[0039] Figure 3 This is a schematic diagram of the second flow channel of the present invention;

[0040] Figure 4 This is a cross-sectional view of the sensor base of the present invention;

[0041] Figure 5 This is a schematic diagram of the sensor chip installation of the present invention;

[0042] Figure 6 This is a cross-sectional view of the sensor chip of the present invention;

[0043] Figure 7 This is a top view of the glass encapsulation layer of the present invention;

[0044] Figure 8 This is an isometric view of the glass encapsulation layer of the present invention;

[0045] Figure 9This is a schematic diagram of a Venturi nozzle structure;

[0046] Figure 10 This is a schematic diagram showing the location of the oil injection hole in this invention;

[0047] Figure 11 Test curves of the liquid-cooled high-temperature pressure sensor provided by the present invention at different temperatures.

[0048] In the attached diagram: 1-Outer shell; 2-Ceramic heat insulation ring; 3-Core; 4-Second cavity inner spiral tube; 5-Corrugated sheet; 6-Bonding alloy wire; 7-Sensor chip; 8-First cavity inner spiral tube; 9-Embedded spiral tube; 10-Metal pin; 11-Main liquid outlet channel; 12-Main liquid inlet channel; 13-Sensor base; 14-Sensitive layer; 15-Sealing layer; 16-Glass encapsulation layer; 17-Pressure-sensitive diaphragm; 18-Pressure cavity; 19-Bonding area; 20-Microchannel; 21- Venturi nozzle; 22- Annular channel; 23- First sub-embedded spiral tube; 24- Second sub-embedded spiral tube; 25- First liquid inlet channel; 26- Second liquid inlet channel; 27- Third liquid inlet channel; 28- First liquid outlet channel; 29- Second liquid outlet channel; 30- Third liquid outlet channel; 31- Fourth liquid inlet channel; 32- Fourth liquid outlet channel; 33- Chip liquid inlet channel; 34- Chip liquid outlet channel; 35- Oil injection hole; 36- Contraction section; 37- Throat; 38- Expansion section.

[0049] Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 7 The dashed arrows in the diagram indicate the direction of coolant flow. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the invention.

[0051] Reference Figures 1 to 10 This embodiment provides a liquid-cooled high-temperature pressure sensor, which mainly consists of a sensor base 13, a corrugated sheet 5, a microfluidic cooling system, and a sensor chip 7. The sensor chip 7 includes a sensitive layer 14, a sealing layer 15, and a glass encapsulation layer 16 arranged sequentially from top to bottom.

[0052] Reference Figures 1 to 5The microfluidic cooling system is the core of in-situ cooling. It includes a first internal spiral tube 8, a second internal spiral tube 4, an embedded spiral tube 9, a microfluidic channel 20 integrated in the sensor chip 7, a main liquid outlet channel 11, a main liquid inlet channel 12, a first liquid inlet channel 25, a second liquid inlet channel 26, a third liquid inlet channel 27, a fourth liquid inlet channel 31, a first liquid outlet channel 28, a second liquid outlet channel 29, a third liquid outlet channel 30, and a fourth liquid outlet channel 32.

[0053] Reference Figure 1 The sensor base 13 is an integral structure formed by sintering a core 3, a shell 1, a ceramic heat insulation ring 2, and metal pins 10. The shell 1 serves as the external protective structure; the ceramic heat insulation ring 2 and the core 3 are both located in the lower part of the shell 1. The core 3 is U-shaped, and the ceramic heat insulation ring 2 is located between the shell 1 and the core 3, utilizing the low thermal conductivity of the ceramic material to reduce the heat transfer efficiency between the shell 1 and the core 3, serving as the first cooling layer for the sensor chip 7. The metal pins 10 are fixed to the core 3. The top of the sensor base 13 is welded to the corrugated sheet 5 to form a sealed cavity. This cavity is enclosed by the core 3, shell 1, ceramic heat insulation ring 2, and corrugated sheet 5, and is filled with degassed, high-temperature resistant hydraulic oil as the pressure transmission medium. The sensor chip 7 is fixed in the cavity with high-temperature adhesive and connected to the metal pins 10 via bonding wires 6 to extract electrical signals.

[0054] Reference Figures 2 to 6 The main liquid outlet channel 11 and the main liquid inlet channel 12 are located at the bottom of the core 3. The inlets of the first liquid inlet channel 25, the second liquid inlet channel 26, the third liquid inlet channel 27, and the fourth liquid inlet channel 31 are all connected to the main liquid inlet channel 12. The outlet of the first liquid inlet channel 25 is connected to the inlet of the first inner cavity spiral tube 8, and the outlet of the first inner cavity spiral tube 8 is connected to the inlet of the first liquid outlet channel 28, forming a first flow channel. The outlet of the second liquid inlet channel 26 is connected to the inlet of the second inner cavity spiral tube 4, and the outlet of the second inner cavity spiral tube 4 is connected to the inlet of the second inner cavity spiral tube 4. The outlet of the first liquid outlet channel 28 is connected to the inlet of the second liquid outlet channel 29 to form a second flow channel; the outlet of the third liquid inlet channel 27 is connected to the inlet of the embedded spiral tube 9, and the outlet of the embedded spiral tube 9 is connected to the inlet of the third liquid outlet channel 30; the inlet of the chip liquid inlet channel 33 is connected to the outlet of the fourth liquid inlet channel 31, and the outlet of the chip liquid outlet channel 34 is connected to the inlet of the fourth liquid outlet channel 32; the outlets of the first liquid outlet channel 28, the second liquid outlet channel 29, the third liquid outlet channel 30, and the fourth liquid outlet channel 32 are all connected to the main liquid outlet channel 11.

[0055] Reference Figure 2 and Figure 3The first internal spiral tube 8 and the second internal spiral tube 4 serve as the second cooling layer for the sensor chip 7, and are arranged inside the oil-filled cavity. The first internal spiral tube 8 and the second internal spiral tube 4 adopt a parallel staggered arrangement structure, meaning that the liquid inlet and outlet channels of the first internal spiral tube 8 and the second internal spiral tube 4 are independent and do not affect each other, and are spatially staggered. Both the first internal spiral tube 8 and the second internal spiral tube 4 include a connected upper spiral tube and a lower spiral tube. The upper spiral tube of the first internal spiral tube 8 and the second internal spiral tube 4 is located at the upper part of the cavity, with its upper end adjacent to the corrugated sheet 5, used to intercept externally transmitted heat; the lower spiral tube of the first internal spiral tube 8 and the second internal spiral tube 4 tightly surrounds the outer periphery of the sensor chip 7, used to maintain the ambient temperature of the sensor chip 7. The first internal spiral tube 8 and the second internal spiral tube 4 are spatially staggered, together forming a double spiral structure, increasing the heat exchange area.

[0056] Preferably, both the first inner-cavity spiral tube 8 and the second inner-cavity spiral tube 4 adopt a variable pitch and variable diameter design, with a length of approximately 175 mm. The upper spiral tube adopts a small diameter, high-density spiral structure with a diameter of φ0.2 mm and a pitch of 0.6 mm to construct an efficient liquid heat shield layer. In the lower spiral tube, a large diameter, sparse spiral structure with a diameter of φ0.2~φ0.32 mm and a pitch of 0.6~0.74 mm is adopted, which, together with the embedded spiral tube 9, maintains constant temperature and optimizes flow resistance.

[0057] Reference Figure 4 The embedded spiral tube 9, serving as the third cooling layer for the sensor chip 7, is located inside the core 3 directly below the sensor chip 7. It employs a series-connected double-spiral structure and is approximately 75mm long. The embedded spiral tube 9 consists of a spirally ascending first sub-embedded spiral tube 23 and a spirally descending second sub-embedded spiral tube 24, arranged in a tightly interlaced double spiral configuration. Both the first sub-embedded spiral tube 23 and the second sub-embedded spiral tube 24 have a diameter of φ0.2mm and a pitch of 0.6mm. The main liquid inlet channel 12 is connected to the inlet of the first sub-embedded spiral tube 23 via a third liquid inlet channel 27. The outlet of the first sub-embedded spiral tube 23 and the inlet of the second sub-embedded spiral tube 24 are connected at the top. The outlet of the second sub-embedded spiral tube 24 is connected to the main liquid outlet channel 11 via a third liquid outlet channel 30. The spirally ascending first sub-embedded spiral tube 23 and the spirally descending second sub-embedded spiral tube 24 are arranged alternately. The coolant enters the first sub-embedded spiral tube 23 from the main inlet channel 12 through the third inlet channel 27, spirals up to the top along the first sub-embedded spiral tube 23, spirals down to the bottom along the second sub-embedded spiral tube 24, and is discharged from the main outlet channel 11 after passing through the third outlet channel 30.

[0058] Reference Figure 7 and Figure 8 The microfluidic channel 20 is located in the glass encapsulation layer 16 and includes a Venturi nozzle array, an annular channel 22, a chip liquid inlet channel 33, and four chip liquid outlet channels 34. The chip liquid inlet channel 33, the Venturi nozzle array, and the annular channel 22 are arranged sequentially from the inside to the outside. The Venturi nozzle array includes six Venturi nozzles 21. The chip liquid inlet channel 33 is located at the center, and the six Venturi nozzles 21 are arranged around the chip liquid inlet channel 33. The chip liquid inlet channel 33 and the four chip liquid outlet channels 34 are all arranged vertically and penetrate the glass encapsulation layer 16. The outlet at the upper end of the chip liquid inlet channel 33 is connected to the Venturi nozzle array, and the inlet at the upper end of the chip liquid outlet channel 34 is connected to the Venturi nozzle array through the annular channel 22. The coolant flows out from the chip inlet channel 33, then into the constriction section 36 of the venturi nozzle 21. After being accelerated by the throat 37, it flows from the expansion section 38 to the annular channel 22, and then flows through the annular channel 22 to the inlet of the chip outlet channel 34. It then flows through the outlet of the chip outlet channel 34 to the inlet of the fourth outlet channel 32, and finally flows through the outlet of the fourth outlet channel 32 to the main outlet channel 11.

[0059] The embedded spiral tube 9 can directly cool the core 3 and remove the heat conducted from the bottom of the sensor chip 7.

[0060] Reference Figures 6 to 9 The sensor chip 7 consists of a sensitive layer 14, a sealing layer 15, and a glass encapsulation layer 16. The sensitive layer 14 serves as the pressure-sensing surface, with its back side bonded to the front side of the sealing layer 15 to form a pressure cavity 18. A pressure-sensitive diaphragm 17 is fabricated on the sensitive layer 14. The back side of the sealing layer 15 is bonded to the glass encapsulation layer 16, which has microchannels 20. The microchannels 20 serve as the final cooling layer for the sensor chip 7, and are embedded within the glass encapsulation layer 16, located around the bonding area 19 of the sensor chip 7. The Venturi nozzle 21 consists of a constriction section 36, a throat 37, and an expansion section 38 connected in sequence, forming a wide-narrow-wide alternating series structure. It utilizes the significant reduction in the cross-sectional area of ​​the throat 37 to make the pressure behind the fluid greater than the pressure in front, creating a pressure difference. The net thrust generated by this pressure difference continuously does work to accelerate the fluid. This invention utilizes the characteristic of Venturi nozzle structure to accelerate fluid. A Venturi nozzle array consisting of six Venturi nozzles 21 is integrated in the microchannel 20. When the coolant flows through the narrow throat 37 in each Venturi nozzle 21, the flow velocity increases sharply, forming a high-speed jet, which significantly enhances the heat exchange efficiency of the sensor chip 7.

[0061] In terms of flow path connection, the first internal spiral tube 8, the second internal spiral tube 4, the embedded spiral tube 9, and the microchannel 20 are connected in parallel, with their inlets all connected to the main inlet channel 12 and their outlets all connected to the main outlet channel 11. Coolant is injected from the main inlet channel 12, simultaneously flowing through the first internal spiral tube 8, the second internal spiral tube 4, the embedded spiral tube 9, and the microchannel 20, finally converging and discharging into the main outlet channel 11. The first internal spiral tube 8, the second internal spiral tube 4, the embedded spiral tube 9, and the microchannel 20 work together to ensure that the cooling effect directly acts on the sensor chip 7, maintaining a constant temperature around the sensor chip 7 and achieving full-enclosure in-situ cooling of the sensor chip 7. In-situ cooling refers to the cooling effect of the second, third, and fourth cooling layers directly acting on the sensor chip 7 and its surrounding microenvironment. In-situ cooling ensures that when the pressure sensor operates at 800℃, the temperature rise of the sensor chip 7 is within 3℃.

[0062] Reference Figure 10 The oil injection hole 35 is located inside the core 3, and its upper end is connected to the cavity on the upper part of the sensor base 13. After the top of the sensor base 13 and the corrugated sheet 5 are welded to form a sealed cavity, hydraulic oil is injected into the cavity through the oil injection hole 35.

[0063] Figure 11 The test curves of the liquid-cooled high-temperature pressure sensor at different temperatures are shown. Calculations show that the nonlinear error of the liquid-cooled high-temperature pressure sensor across the entire temperature range is within 0.2%FS, and the overall accuracy is within ±0.2%FS, proving that the liquid-cooled high-temperature pressure sensor can accurately measure pressure signals at 800℃. Furthermore, since the actual temperature of the sensor chip when operating at 800℃ cannot be measured, the test results show that the zero-point output and full-scale output variation of the liquid-cooled high-temperature pressure sensor are both within 5mV across the entire temperature range. Combining the performance indicators of 1.5%FS / ℃ thermal zero-point drift and 1.5%FS / ℃ thermal full-scale output drift of the sensor chip, it is calculated that the sensor chip temperature rise is approximately 2.5℃ when operating at 800℃.

[0064] The present invention also provides a method for manufacturing the above-mentioned liquid-cooled high-temperature pressure sensor, comprising the following steps:

[0065] Step 1: Take an SOI silicon wafer and fabricate the piezoresistive region, insulating layer and metal electrode on its front side using standard MEMS processes such as photolithography, doping and deposition.

[0066] Step 2: Etch the back side of the SOI silicon wafer to obtain a pressure-sensitive layer 14 with pressure-sensitive film 17;

[0067] Step 3: Take a single crystal silicon wafer and thin it to serve as the sealing layer 15. Connect the single crystal silicon wafer to the back of the sensitive layer 14 through an anodic bonding process to form a pressure cavity 18, thus obtaining a structure with a sensitive layer 14 and a sealing layer 15.

[0068] Step 4: Take a glass wafer and use femtosecond laser processing to prepare microchannels 20 inside the glass wafer to form a glass encapsulation layer 16. Bond the front side of the glass wafer to the back side of the structure with a sensitive layer 14 and a sealing layer 15. Finally, obtain an independent sensor chip 7 through a dicing process.

[0069] Step 5: The core 3, the first inner spiral tube 8, and the second inner spiral tube 4 are integrally processed by metal 3D printing technology. The core 3 has an embedded spiral tube 9, a main liquid inlet channel 12, a main liquid outlet channel 11, a first liquid inlet channel 25, a second liquid inlet channel 26, a third liquid inlet channel 27, a fourth liquid inlet channel 31, a first liquid outlet channel 28, a second liquid outlet channel 29, a third liquid outlet channel 30, a fourth liquid outlet channel 32, and an oil injection hole 35. The core 3 is assembled with the outer shell 1, the ceramic heat insulation ring 2, and the metal pins 10 and sintered at high temperature to obtain the sensor base 13.

[0070] Step 6: The prepared sensor chip 7 is bonded to the core 3 of the sensor base 13 using high-temperature resistant adhesive. During the bonding process, the inlet of the chip liquid inlet channel 33 is aligned with the outlet of the fourth liquid inlet channel 31, and the outlet of the chip liquid outlet channel 34 is aligned with the fourth liquid outlet channel 32 before installation. Then, using wire bonding technology, the metal pads on the sensor chip 7 are connected to the metal pins 10 through the bonding wire 6 to achieve electrical signal conduction.

[0071] Step 7: Weld the corrugated sheet 5 to the top of the sensor base 13 to form a cavity. Inject high-temperature resistant hydraulic oil that has been degassed through the oil injection hole 35 and then weld the oil injection hole to seal it, thus obtaining a microchannel in-situ liquid-cooled high-temperature pressure sensor.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A liquid-cooled high-temperature pressure sensor, characterized in that, Including the sensor package body, microfluidic cooling system and sensor chip (7); The sensor packaging body includes a sensor base (13) and a corrugated sheet (5). The sensor base (13) includes a shell (1), a ceramic heat insulation ring (2) and a core (3) arranged sequentially from the outside to the inside. The corrugated sheet (5) is connected to the shell (1) to form a cavity. The cavity is filled with hydraulic oil. The sensor chip (7) is fixed at the bottom of the cavity. The microchannel cooling system includes a first intracavity spiral tube (8) and a second intracavity spiral tube (4) disposed in the cavity, an embedded spiral tube (9) disposed inside the core (3), and a microchannel (20) disposed in the sensor chip (7). The lower parts of the first intracavity helical tube (8) and the second intracavity helical tube (4) are both surrounding the sensor chip (7); The embedded helical tube (9) is located directly below the sensor chip (7); The sensor chip (7) includes a sensitive layer (14), a sealing layer (15) and a glass encapsulation layer (16) bonded together in sequence, and the glass encapsulation layer (16) is provided with microchannels (20). The microchannel (20) includes a chip inlet channel (33), a venturi nozzle array, and a chip outlet channel (34). The venturi nozzle array includes multiple venturi nozzles (21) arranged circumferentially along the chip inlet channel (33). The constriction section (36) of the venturi nozzle (21) is located on the side closer to the chip inlet channel (33), and the expansion section (38) of the venturi nozzle (21) is located on the side closer to the chip outlet channel (34). Both the chip inlet channel (33) and the chip outlet channel (34) are connected to the venturi nozzle array.

2. The liquid-cooled high-temperature pressure sensor according to claim 1, characterized in that, The first internal spiral tube (8) and the second internal spiral tube (4) are connected in parallel and arranged in an alternating double spiral structure.

3. The liquid-cooled high-temperature pressure sensor according to claim 1, characterized in that, The diameter of the upper half of the first internal spiral tube (8) is smaller than that of the lower half, and the pitch of the upper half is smaller than that of the lower half; the diameter of the upper half of the second internal spiral tube (4) is smaller than that of the lower half, and the pitch of the upper half is smaller than that of the lower half.

4. A liquid-cooled high-temperature pressure sensor according to claim 1, characterized in that, The embedded helical tube (9) is a double helical structure connected in series.

5. A liquid-cooled high-temperature pressure sensor according to claim 1, characterized in that, An annular channel (22) is provided outside the Venturi nozzle array, and the annular channel (22) is connected to the Venturi nozzle array. The chip liquid outlet channel (34) is vertically arranged and connected to the annular channel (22).

6. A liquid-cooled high-temperature pressure sensor according to claim 1, characterized in that, The inlets of the first cavity spiral tube (8), the second cavity spiral tube (4), the embedded spiral tube (9) and the microchannel (20) are all connected to the main liquid inlet channel (12), and the outlets are all connected to the main liquid outlet channel (11). The main liquid inlet channel (12) and the main liquid outlet channel (11) are both located at the bottom of the core (3).

7. The method for manufacturing a liquid-cooled high-temperature pressure sensor according to claim 1, characterized in that, Includes the following steps: Step 1: Form a piezoresistive region, an insulating layer, and a metal electrode on the front side of an insulator-on-silicon wafer; Step 2: Process the back side of the silicon wafer on the insulator to form a sensitive layer (14). Step 3: Thin the single-crystal silicon wafer to serve as a sealing layer (15), and bond the sealing layer (15) to the back side of the silicon-on-insulator wafer to form a pressure cavity (18), thus obtaining a structure with a sensitive layer (14) and a sealing layer (15); Step 4: Microchannels (20) are fabricated in the glass wafer and bonded to the back side of the structure with a sensitive layer (14) and a sealing layer (15) obtained in Step 3 to form a glass encapsulation layer (16). The sensor chip (7) is obtained by dicing. Step 5: Prepare the assembly, which includes a core (3), a first cavity helical tube (8) and a second cavity helical tube (4). The core (3) has the embedded helical tube (9) pre-placed inside. The core (3) is assembled and sintered with the outer shell (1), ceramic heat insulation ring (2) and metal pin (10) to obtain the sensor base (13). Step 6: Attach the sensor chip (7) to the core (3) and connect the metal pads of the sensor chip (7) to the metal pins (10) by bonding wire (6); Step 7: Seal the corrugated sheet (5) with the sensor base (13) to form a cavity, and inject hydraulic oil into the cavity to obtain a liquid-cooled high-temperature pressure sensor.

8. The method for fabricating a liquid-cooled high-temperature pressure sensor according to claim 7, characterized in that, In step 4, a femtosecond laser is used to process microchannels (20) inside the glass wafer.

9. The method for manufacturing a liquid-cooled high-temperature pressure sensor according to claim 7, characterized in that, In step 5, the composite is prepared by metal 3D printing in one piece.

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