Micro high-dose radiation detection device and method of capacitive MEMS and application of micro high-dose radiation detection device and method

Abstract

The invention belongs to the technical field of radioactivity detection, and particularly relates to a capacitive MEMS miniature high-dose radiation detection device and method and application, the device comprises a sensitive structure layer, a bonding layer and a bottom plate layer, the bonding layer is located between the sensitive structure layer and the bottom plate layer, and the sensitive structure layer, the bonding layer and the bottom plate layer define a closed vacuum cavity (5); a polymer material (9) is arranged in the vacuum cavity (5), and the amount of gas released by the polymer material (9) is in direct proportion to the received ionizing radiation dose. The sensitive layer elastic thin film is thin, deformation generated by pressure change of the vacuum cavity mainly occurs at the sensitive layer elastic thin film, the deformation quantity of the sensitive layer capacitance polar plate is small, and the linearity between the capacitance value variable quantity and the ionization radiation dose variable quantity is effectively improved.

Description

Technical Field

[0001] This invention belongs to the field of radioactivity detection technology, specifically relating to a capacitive MEMS miniature high-dose radiation detection device, method, and application. Background Technology

[0002] High-energy radiation doses exceeding 10 kGy are found in experimental research facilities such as nuclear power plants, the Large Hadron Collider, the European Free Electron Laser Project, and the International Thermonuclear Experimental Reactor, as well as at nuclear facility decommissioning sites. Measuring these doses presents a significant practical challenge. High-energy radiation can severely damage the structural materials of these facilities; therefore, it is essential to measure the radiation dose absorbed by these materials to ensure their safe operation.

[0003] Currently known electronic dosimeters for detecting high-dose ionizing radiation mainly consist of conductive sensors. The interaction between high-energy radiation and π-conductor elements limits the measurement of the maximum radiation dose to tens of kGy. Passive dosimeters, such as thermoluminescent dosimeters, optically stimulated luminescent dosimeters, and alanine dosimeters, can measure radiation doses exceeding tens of kGy, but continuous measurements are not possible because the detector must be moved from the monitoring area to the readout device.

[0004] With the rapid development of IoT technology, the demand for low-power, high-precision sensor systems in the environmental monitoring field is increasing. MEMS sensors, with their advantages of small size, light weight, low power consumption, high reliability, high sensitivity, easy integration, and resistance to harsh working environments, are gradually replacing the dominant position of traditional mechanical sensors.

[0005] As can be seen from the above introduction, with the development of nuclear energy and particle accelerators, in order to ensure the safe operation of facilities such as reactors and accelerators and to assess the radiation damage effect of high-dose high-energy radiation on the structural materials of the facilities, it is necessary to develop a new type of detector to measure the high-dose radiation that occurs in the above facilities in real time. Summary of the Invention

[0006] To address the problems existing in the prior art, the present invention aims to propose a passive micromechanical high-dose high-energy radiation sensor structure that combines the ability to measure high-dose high-energy radiation (>10kGy) with the advantages of direct sensing. This provides a passive, maintenance-free, radiation-damage-resistant MEMS detection device, method, and application, achieving miniaturization (chip-level size ≤5mm×5mm×1mm) and high-dose range coverage (1kGy~100kGy). It meets the needs of distributed dose monitoring in extreme environments and is suitable for cumulative radiation dose monitoring in fields such as nuclear industry, aerospace, and medical irradiation.

[0007] To achieve the above-mentioned objectives, the technical solution of the present invention is as follows:

[0008] A miniature high-dose radiation detection device for capacitive MEMS includes a sensitive structure layer, a bonding layer, and a base plate layer. The bonding layer is located between the sensitive structure layer and the base plate layer. The sensitive structure layer, the bonding layer, and the base plate layer enclose a sealed vacuum cavity. A polymer material is disposed inside the vacuum cavity. The amount of gas released by the polymer material is proportional to the received ionizing radiation dose.

[0009] Furthermore, the sensitive structure layer includes a sensitive layer outer frame, a sensitive layer border, and a sensitive layer capacitor plate. The periphery of the sensitive layer capacitor plate is connected to the sensitive layer border via a sensitive layer elastic film, and the outer side of the sensitive layer border is connected to the sensitive layer outer frame via an upper cantilever beam. The base plate layer includes a base plate outer frame and a base plate capacitor plate. The outer side of the base plate capacitor plate is connected to the base plate outer frame via a lower cantilever beam. The bonding layer includes a bonding layer outer frame and a bonding layer border. The bonding layer border is disposed inside the bonding layer outer frame, between the sensitive layer outer frame and the base plate outer frame, and between the sensitive layer border and the base plate capacitor plate.

[0010] Furthermore, a sensitive layer metal electrode is provided on the upper suspension beam, and the sensitive layer metal electrode is electrically connected to the sensitive layer capacitor plate.

[0011] Furthermore, a bottom plate metal electrode is provided on the lower suspension beam, and the bottom plate metal electrode is electrically connected to the bottom plate capacitor plate.

[0012] Furthermore, the vacuum cavity is formed by the sensitive layer frame, the sensitive layer elastic film, the sensitive layer capacitor plate, the bonding layer frame, and the bottom plate capacitor plate, serving as a capacitor gap.

[0013] Furthermore, the outer frame of the sensitive layer, the border of the sensitive layer, and the capacitor plate of the sensitive layer have the same thickness, and the thickness of the capacitor plate of the sensitive layer is greater than the thickness of the elastic film of the sensitive layer; the outer frame of the bottom plate layer and the capacitor plate of the bottom plate layer have the same thickness; the thickness of the bonding layer is equal to the distance between the capacitor plate of the sensitive layer and the capacitor plate of the bottom plate layer.

[0014] Furthermore, the sensitive structural layer is made of monocrystalline silicon, the bonding layer is made of silicon dioxide, and the base plate layer is made of borosilicate glass.

[0015] Furthermore, the polymer material is polyethylene, polypropylene, or polymethyl methacrylate.

[0016] A method for detecting high-dose radiation using the above-mentioned device includes the following steps:

[0017] Step 1: Calibrate the detection device in a standard radiation field;

[0018] Step 2: Irradiate the polymer material with high-energy radiation;

[0019] Step 3: Measure the change in capacitance of the detection device;

[0020] Step 4: Obtain the ionizing radiation dose based on the change in capacitance in Step 3.

[0021] In a specific implementation, the capacitive MEMS miniature high-dose radiation detection device described above is applied to the monitoring of cumulative radiation dose in nuclear industry, aerospace, or medical irradiation.

[0022] The beneficial effects of this invention are as follows:

[0023] 1. During use, when ionizing radiation interacts with the polymer in the vacuum chamber, gas is released, increasing the pressure in the vacuum chamber and causing the elastic film of the sensitive layer to deform. This changes the capacitance value of the parallel plate capacitor formed between the capacitor plates of the sensitive layer and the capacitor plates of the bottom layer. Measuring this capacitance value can obtain gas pressure information. The amount of gas released by the polymer in the vacuum chamber is proportional to the received ionizing radiation dose. The change in ionizing radiation dose can be obtained from the obtained capacitance change (gas pressure change).

[0024] 2. The elastic film of the sensitive layer is relatively thin, and the deformation caused by the change in vacuum cavity pressure mainly occurs at the elastic film of the sensitive layer. The deformation of the capacitor plates of the sensitive layer is small, which effectively improves the linearity between the change in capacitance value and the change in ionizing radiation dose. Attached Figure Description

[0025] Figure 1 This is a cross-sectional view of a micro high-dose radiation detection device of capacitive MEMS.

[0026] In the above figures, 1 is the outer frame of the sensitive layer; 2 is the upper suspension beam; 3 is the border of the sensitive layer; 4 is the elastic film of the sensitive layer; 5 is the vacuum cavity; 6 is the capacitor electrode of the sensitive layer; 7 is the outer frame of the bonding layer; 8 is the border of the bonding layer; 9 is the polymer material; 10 is the capacitor plate of the bottom plate; 11 is the lower suspension beam; and 12 is the outer frame of the bottom plate. Detailed Implementation

[0027] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0028] A miniature high-dose radiation detection device for capacitive MEMS includes a sensitive structure layer, a bonding layer, and a base plate layer. The bonding layer is located between the sensitive structure layer and the base plate layer. The sensitive structure layer, the bonding layer, and the base plate layer enclose a sealed vacuum cavity 5. A polymer material 9 is disposed inside the vacuum cavity 5. The amount of gas released by the polymer material 9 is proportional to the received ionizing radiation dose.

[0029] Example 1

[0030] This invention employs, as follows Figure 1The illustrated capacitive MEMS miniature high-dose radiation detection device includes a sensitive structure layer, a bonding layer, and a base plate layer arranged sequentially from top to bottom.

[0031] The sensitive structure layer includes a sensitive layer outer frame 1, a sensitive layer border 3, and a sensitive layer capacitor plate 6. The periphery of the outer edge of the sensitive layer capacitor plate 6 is connected to the sensitive layer border 3 via a sensitive layer elastic film 4. The sensitive layer border 3 is continuously distributed and its outline forms a closed geometric shape. The outer side of the sensitive layer border 3 is connected to the sensitive layer outer frame 1 via an upper suspension beam 2. The sensitive layer outer frame 1 is continuously distributed and its outline forms a closed geometric shape. A sensitive layer metal electrode is disposed on the upper suspension beam 2, and the sensitive layer metal electrode is electrically connected to the sensitive layer capacitor plate 6.

[0032] The outer frame 1, the border 3, and the capacitor plate 6 of the sensitive layer have the same thickness, and the thickness of the capacitor plate 6 of the sensitive layer is greater than the thickness of the elastic film 4 of the sensitive layer.

[0033] The base plate layer includes a base plate layer outer frame 12 and a base plate layer capacitor plate 10. The outer edge of the base plate layer capacitor plate 10 is connected to the base plate layer outer frame 12 via a lower suspension beam 11. The base plate layer outer frame 12 is continuously distributed and its outline is a closed geometric shape. A base plate layer metal electrode is disposed on the lower suspension beam 11, and the base plate layer metal electrode is electrically connected to the base plate layer capacitor plate 10.

[0034] The outer frame 12 of the bottom plate layer and the capacitor plate 10 of the bottom plate layer have the same thickness.

[0035] The bonding layer includes a bonding layer outer frame 7 and a bonding layer border 8. The bonding layer border 8 is disposed inside the bonding layer outer frame 7. Both the bonding layer outer frame 7 and the bonding layer border 8 are continuously distributed, and their outlines are closed geometric shapes. The bonding layer outer frame 7 is disposed between the sensitive layer outer frame 1 and the base layer outer frame 12, and the bonding layer border 8 is disposed between the sensitive layer border 3 and the edge of the base layer capacitor plate 10.

[0036] The thickness of the bonding layer, namely the thickness of the bonding layer outer frame 7 and the bonding layer border 8, is equal to the distance between the sensitive layer capacitor plate 6 and the bottom layer capacitor plate 10.

[0037] A sealed vacuum cavity 5, consisting of a sensitive layer frame 3, a sensitive layer elastic film 4, a sensitive layer capacitor plate 6, a bonding layer frame 8, and a bottom layer capacitor plate 10, serves as a capacitor gap. A polymer material 9 is placed inside the vacuum cavity 5. The amount of gas released by the polymer material 9 is proportional to the ionizing radiation dose it receives. The polymer material 9 within the vacuum cavity 5 interacts with ionizing radiation to release gas, thereby deforming the sensitive layer elastic film 4. The change in radiation dose is obtained based on the change in capacitance.

[0038] The sensitive structural layer is made of monocrystalline silicon, and the bonding layer is made of insulating silicon dioxide. Silicon dioxide has similar mechanical properties to monocrystalline silicon, but exhibits better strain uniformity and bonding strength. The substrate layer is made of borosilicate glass resistant to high-energy radiation.

[0039] The polymer material 9 placed inside the vacuum chamber 5 is polyethylene, polypropylene, or polymethyl methacrylate. These polymer materials 9 interact with ionizing radiation and release gas.

[0040] When polyethylene is irradiated with high-energy radiation (such as gamma rays, electron beams, or proton beams), it triggers complex radiochemical reactions, leading to polymer radiolysis and cross-linking. In this process, gaseous products are among the important radiolysis products. Within the MGy radiation dose range, the amount of gas produced is directly proportional to the absorbed dose; therefore, this detection device is suitable for high-dose radiation detection.

[0041] Radiation energy is absorbed by the polymer, primarily triggering the breakage of the main chain or side chains, generating free radicals. These free radicals interact or react with small molecules, directly producing small molecule gases (mainly hydrogen (H2), followed by methane (CH4), and small amounts of ethane (C2H6), ethylene (C2H4), propane (C3H8), etc.). Each radiation event is relatively independent, and the gas yield (G value, defined as the number of molecules produced per 100 eV of absorbed energy) is approximately constant within a certain dose range. Therefore, the cumulative gas yield is proportional to the cumulative dose. High-energy radiation irradiation of polyethylene materials releases gases, leading to an increase in pressure within the sealed vacuum chamber 5, which in turn causes deformation of the elastic film 4 of the sensitive layer, resulting in a change in capacitance. Calibration is performed in a standard radiation field before use, and the ionizing radiation dose can be obtained by measuring the change in capacitance.

[0042] The aforementioned capacitive MEMS miniature high-dose radiation detection device can be applied to the monitoring of cumulative radiation dose in nuclear industry, aerospace or medical irradiation.

[0043] Example 2

[0044] The high-dose radiation detection method using this device includes the following steps:

[0045] Step 1: calibrate the detector in a standard radiation field; place the detector in the standard radiation field, measure the capacitance value of the detector when it is not irradiated, irradiate the detector with a standard source of known activity, and read the capacitance value of the detector at regular intervals to obtain the correspondence between the change in the capacitance value of the detector and the cumulative radiation dose of the standard source.

[0046] Step 2: Irradiate the polymer material with high-energy radiation; place the detection device and the object to be monitored in the same position so that the radiation source irradiates the detection device.

[0047] Step 3: Measure the change in capacitance of the detection device; after being irradiated by the radiation source for a period of time, record the capacitance value of the detection device to obtain the change in capacitance of the detection device.

[0048] Step 4: Obtain the ionizing radiation dose based on the change in capacitance recorded in Step 3. Based on the recorded change in capacitance of the detection device, and by relating the change in capacitance of the detection device to the cumulative radiation dose of the standard source, the ionizing radiation dose of the detection device is obtained.

[0049] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. Thus, the invention also intends to include any such variations, uses, or adaptations that fall within the scope of the claims and their equivalents.

[0050] The above embodiments are merely illustrative examples of the present invention. The present invention may also be implemented in other specific ways or forms without departing from its spirit or essential characteristics. Therefore, the described embodiments should be considered illustrative rather than limiting in any respect. The scope of protection of the present invention should be defined by the claims, and any variations equivalent to the intent and scope of the claims should also be included within the scope of the present invention.

Claims

1. A micro high dose radiation detection device of capacitive MEMS, characterized in that: It comprises a sensitive structure layer, a bonding layer and a bottom plate layer, the bonding layer is between the sensitive structure layer and the bottom plate layer, the sensitive structure layer, the bonding layer and the bottom plate layer enclose a closed vacuum cavity (5), a polymer material (9) is arranged in the vacuum cavity (5), and the amount of gas released by the polymer material (9) is proportional to the received ionizing radiation dose.

2. A micro high dose radiation detection device of capacitive MEMS according to claim 1, characterized in that: The sensitive structure layer comprises a sensitive layer outer frame (1), a sensitive layer frame (3) and a sensitive layer capacitor plate (6), the periphery of the sensitive layer capacitor plate (6) is connected with the sensitive layer frame (3) through a sensitive layer elastic film (4), and the outer side of the sensitive layer frame (3) is connected with the sensitive layer outer frame (1) through an upper suspension beam (2); the bottom plate layer comprises a bottom plate layer outer frame (12) and a bottom plate layer capacitor plate (10), and the outer side of the bottom plate layer capacitor plate (10) is connected with the bottom plate layer outer frame (12) through a lower suspension beam (11); the bonding layer comprises a bonding layer outer frame (7) and a bonding layer frame (8), the bonding layer frame (8) is arranged on the inner side of the bonding layer outer frame (7), the bonding layer outer frame (7) is arranged between the sensitive layer outer frame (1) and the bottom plate layer outer frame (12), and the bonding layer frame (8) is arranged between the sensitive layer frame (3) and the bottom plate layer capacitor plate (10).

3. A micro high dose radiation detector of capacitive MEMS type according to claim 2, characterized in that: The upper suspension beam (2) is provided with a sensitive layer metal electrode, and the sensitive layer metal electrode is electrically connected with the sensitive layer capacitor plate (6).

4. A micro high dose radiation detector of capacitive MEMS according to claim 3, characterized in that: The lower suspension beam (11) is provided with a bottom plate layer metal electrode, and the bottom plate layer metal electrode is electrically connected with the bottom plate layer capacitor plate (10).

5. A micro high dose radiation detector of capacitive MEMS according to claim 2, characterized in that: The vacuum cavity (5) is enclosed by the sensitive layer frame (3), the sensitive layer elastic film (4), the sensitive layer capacitor plate (6), the bonding layer frame (8) and the bottom plate layer capacitor plate (10) and serves as a capacitor gap.

6. A micro high dose radiation detector of capacitive MEMS type according to claim 5, characterized in that: The thicknesses of the sensitive layer outer frame (1), the sensitive layer frame (3) and the sensitive layer capacitor plate (6) are the same, the thickness of the sensitive layer capacitor plate (6) is greater than the thickness of the sensitive layer elastic film (4); the thicknesses of the bottom plate layer outer frame (12) and the bottom plate layer capacitor plate (10) are the same; and the thickness of the bonding layer is equal to the spacing between the sensitive layer capacitor plate (6) and the bottom plate layer capacitor plate (10).

7. A micro high dose radiation detector of capacitive MEMS type according to claim 1, characterized in that: The sensitive structure layer is prepared from monocrystalline silicon, the bonding layer is prepared from silicon dioxide, and the bottom plate layer is prepared from borosilicate glass.

8. A micro high dose radiation detector of capacitive MEMS according to claim 1, characterized in that: The polymer material (9) is polyethylene, polypropylene or polymethyl methacrylate.

9. A method for detecting high dose radiation using the device of any one of claims 1-8, wherein, The method comprises the following steps: Step 1, calibrating the detection device in a standard radiation field; Step 2, irradiating the polymer material with high-energy radiation; Step 3, measuring the change amount of the capacitance of the detection device; Step 4, obtaining the ionizing radiation dose according to the change amount of the capacitance in step 3.

10. The capacitive MEMS micro high dose radiation detector device according to any of claims 1-8, wherein: It is applied to cumulative radiation dose monitoring in the nuclear industry, aerospace or medical irradiation.

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