A micro flexible magnetic temperature sensor device and its preparation method

Abstract

The present invention relates to the field of microsensor technology, and more particularly to a micro-flexible magnetic temperature sensor device and its preparation method. The device comprises a polyimide (PI) flexible substrate and a temperature-sensitive composite material attached to its surface. The temperature-sensitive composite material is selected from one of NiCoMnIn and NiCoMnTi / Cr. The preparation method of the micro-flexible magnetic temperature sensor device of the present invention features simple steps, a wide operating range, a short preparation cycle, a low cost, and simple experimental conditions. It also exhibits excellent performance for monitoring specific temperature ranges and a high temperature response sensitivity.

Description

Technical Field

[0001] The present invention relates to the technical field of micro sensors, and in particular to a micro flexible magnetic temperature sensor device and a preparation method thereof. Background Art

[0002] Temperature, a physical quantity that characterizes the degree of hotness or coldness of an object, is a fundamental measurement parameter in industries such as industrial automation, household appliances, environmental protection, production safety, and the automotive industry. Temperature is the most fundamental and core measurement indicator in temperature monitoring systems, and also the most important controlled parameter in these systems. Therefore, accurate temperature monitoring has always been a crucial research topic. Therefore, temperature measurement instruments play a crucial role in temperature measurement systems. Temperature sensors are widely used and numerous, ranking first among all types of sensors.

[0003] Currently, new temperature sensors are evolving internationally from analog to digital, integrated, intelligent, and networked. Temperature sensors can be divided into two categories based on the contact method between the sensor and the measured medium: contact and non-contact. In contact temperature sensors, the measuring element and the measured object must be in good thermal contact, achieving thermal equilibrium through heat conduction and convection. The displayed value represents the object's temperature. This temperature measurement method offers high accuracy and can measure the temperature distribution within an object. However, this method can produce significant errors for moving objects, objects with small heat capacities, or objects that corrode the sensing element. In non-contact temperature measurement, the measuring element and the measured object do not come into contact. The principle of radiative heat exchange is commonly used. This temperature measurement method is particularly advantageous in that it can measure small moving objects, objects with small or rapidly changing heat capacities, and temperature distribution within a temperature field. However, it is significantly affected by the environment. Summary of the Invention

[0004] In order to overcome the problems of insufficient temperature sensing sensitivity and slow response speed in the prior art, as well as the defects of high cost, harsh test conditions and lack of room for variation in the manufacturable structure, the present invention provides a miniature flexible magnetic temperature sensor device.

[0005] The present invention also provides a method for preparing a micro-flexible magnetic temperature sensor device, which has simple steps, a wide operating space, a short preparation cycle, a low price and simple test conditions.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A micro-flexible magnetic temperature sensor device comprises a polymer flexible substrate, a temperature-sensitive magnetic phase change coil, and a flexible permanent magnetic composite film. The temperature-sensitive magnetic phase change coil is connected to an electrode, the temperature-sensitive magnetic phase change coil is encapsulated on the polymer flexible substrate, a flexible permanent magnetic composite film is provided above the temperature-sensitive magnetic phase change coil, and a space for the flexible permanent magnetic composite film to vibrate is provided between the polymer flexible substrate and the flexible permanent magnetic composite film.

[0008] The micro-flexible magnetic temperature sensor device of the present invention has the characteristics of strong resistance to external influences, and the thickness and size of the micro-flexible magnetic temperature sensor device are controllable. By changing the coil width, number and material thickness, the sensitivity of the device to external temperature changes can be controlled.

[0009] Preferably, the magnetic phase change material is selected from NiCoMnIn and NiCoMnTi. The function of the above materials is to act as temperature-sensitive materials and respond to changes in a specific external temperature range.

[0010] Preferably, the flexible substrate is polyimide (PI). The flexible substrate has the function of having excellent stability as a substrate and good deformability when necessary.

[0011] A method for preparing a micro flexible magnetic temperature sensor device comprises the following steps:

[0012] (A) A PMMA layer is fabricated on a silicon wafer as a sacrificial layer, and then a PI layer is fabricated on the PMMA layer as a polymer flexible substrate.

[0013] (B) depositing a temperature-sensitive magnetic phase change material layer on the substrate surface by magnetron sputtering, annealing, forming a coil pattern by positive photolithography, and removing excess material by lift-off to obtain a temperature-sensitive magnetic phase change coil, and spin-coating a layer of PI on the temperature-sensitive magnetic phase change coil to obtain a substrate for encapsulating the coil;

[0014] (C) mixing and stirring the permanent magnetic material and the A and B components of PDMS, and heating and curing the resulting mixture into a film to obtain a flexible permanent magnetic composite film;

[0015] (D) Assembling the flexible permanent magnetic composite film with the substrate of the encapsulated coil, removing the PMMA layer and the silicon wafer to obtain a micro flexible magnetic temperature sensor device.

[0016] Preferably, in step (A), a substrate with a thickness of 7 μm and a sacrificial layer for stripping the device are attached to the silicon wafer by spin coating, and the spin coating rate and time will affect the thickness of the substrate;

[0017] In step (B), the thickness of the sputtered composite material layer is NiCoMnIn, NiCoMnTi 150nm / Cr 50nm;

[0018] In step (C), the permanent magnet material is selected as NdFeB;

[0019] The present invention combines a flexible substrate, physical deposition technology and photolithography technology, thereby making it easier to design, set the coil pattern, size and thickness, and greatly improve the sensitivity of the temperature sensor to changes in the external environment. The material structure constructed by combining the flexible substrate and physical deposition technology has the advantages of good uniformity, high order and strong repeatability, and is a promising technical means for the preparation of micro devices. Compared with chemical assembly and other technologies, the main advantages of this method are less interference from organic components and simple and controllable material thickness, which is not only beneficial for actual detection applications but also more conducive to batch production. At the same time, the main advantages of the photolithography method are simple steps, clear controllable conditions, and good structural controllability. The micro-flexible magnetic temperature sensor device in the present invention has simple production steps and a short preparation cycle. No expensive reagents are required in the preparation process, so the preparation cost is low, and the experimental conditions are relatively simple.

[0020] By combining a sensing coil with a feedback magnetic film, this invention effectively converts temperature signals into mechanical signals. When a temperature change within a specific range is detected, the vibration amplitude of the magnetic film effectively reflects the temperature change. Due to the unique properties of the selected magnetic phase change material, this invention can be applied to instruments that require strict precision within the material's phase change temperature range.

[0021] Preferably, the thickness of the magnetic phase change material layer is 150nm to 1um. The resulting micro-flexible magnetic temperature sensor device, controlled within the aforementioned parameter range, exhibits high temperature response sensitivity. However, a thicker magnetic phase change material layer may result in incomplete coil lift-off, leading to structural collapse and fracture, impacting device performance. A thinner magnetic phase change material layer may result in excessive device resistance, reducing device temperature response sensitivity.

[0022] Preferably, the composite material layer is NiCoMnIn, NiCoMnTi / Cr,

[0023] Preferably, during the deposition of the temperature-sensitive magnetic phase change material layer, Cr is first deposited to enhance the bonding force between the temperature-sensitive magnetic phase change coil and the polymer flexible substrate, and then the NiCoMnIn layer is deposited.

[0024] Preferably, the flexible substrate is polyimide (PI).

[0025] Preferably, in step (A), a substrate with a thickness of 7 μm and a sacrificial layer for stripping the device are attached to the silicon wafer by spin coating. The rate and time of spin coating will affect the thickness of the substrate.

[0026] Preferably, in step (B), the thickness of the sputtered composite material layer is NiCoMnIn, NiCoMnTi 150nm / Cr 50nm.

[0027] Preferably, in step (C), the permanent magnet material selected is NdFeB.

[0028] The present invention also provides a method for detecting temperature changes in a specific temperature range using a micro-flexible magnetic temperature sensor device, comprising the following steps:

[0029] Selecting a temperature range to be detected, wherein the temperature range includes the temperature at which the phase change material undergoes phase change;

[0030] applying a voltage to the electrode to cause the temperature-sensitive magnetic phase change coil to generate an electromagnetic induction magnetic field;

[0031] When the temperature changes to a temperature at which the phase change material undergoes phase change, the temperature-sensitive magnetic phase change coil generates a change in magnetic field, and the temperature change is fed back through the vibration change of the magnetic film.

[0032] By changing the thickness of the magnetic phase change material layer and the size of the coil, the size of the magnetic field generated by the obtained micro-flexible magnetic temperature sensor device can be controlled, thereby affecting the device's sensitivity to the external temperature.

[0033] Therefore, the present invention has the following beneficial effects:

[0034] (1) The preparation method of the micro-magnetic flexible temperature sensor device of the present invention has the characteristics of simple steps, large operating space, short preparation cycle, low price and simple test conditions, and has excellent performance of high temperature response sensitivity; compared with the traditional temperature measurement method, the provision of a magnetic film can effectively combine the feedback component and the sensing component, and the response speed of such vibration detection temperature is faster.

[0035] (2) The micro-magnetic flexible temperature sensor device of the present invention can be applied to fields such as human-computer interaction and environmental monitoring, and is suitable for a variety of intelligent products. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a schematic diagram of the process for producing the micro-magnetic flexible temperature sensor device obtained in Example 1.

[0037] Figure 2 Schematic diagram of the micro flexible magnetic temperature sensor device prepared in Example 1

[0038] Among them, 1-magnetic film; 2-phase change coil; 3-iron core; 4-PI substrate; 5-electrode

[0039] Figure 3 This is an SEM image of the magnetic film of the micro-magnetic flexible temperature sensor device prepared in Example 1.

[0040] Figure 4 This is an SEM image of the magnetic film of the micro-magnetic flexible temperature sensor device prepared in Example 3. DETAILED DESCRIPTION

[0041] The technical solution of the present invention will be further described in detail below through specific embodiments in conjunction with the accompanying drawings.

[0042] In the present invention, unless otherwise specified, all equipment and raw materials can be purchased from the market or are commonly used in the industry. The methods in the following embodiments, unless otherwise specified, are all conventional methods in the art.

[0043] Example 1

[0044] according to Figure 1 The flow chart shown below is for preparing a micro-magnetic flexible temperature sensor device with a composite material of NiCoMnIn / Cr:

[0045] (A) First, a 1 μm thick PMMA layer was fabricated on a silicon wafer as a sacrificial layer for the device. Then, a 7 μm thick PI layer was fabricated on the PMMA as a substrate.

[0046] (B) On the flexible substrate surface, the vacuum degree is 8×10 -6 Under the conditions of Pa, Ar gas flux of 100 SCCM, and sputtering power of 60W, a 150nm / 50nm thick NiCoMnIn / Cr layer was magnetron sputtered. The Cr layer was used to strengthen the bonding between the coil and the substrate. The device structure was fabricated by positive resist lithography, and the excess material was removed by lift-off. The surface of the obtained micro-flexible magnetic temperature sensor device was spin-coated with a 2μm thick PI layer as a device encapsulation effect.

[0047] (C) PDMS components A and B were mixed in a mass ratio of 10:1, and 40% by mass of NdFeB was added. The mixture was stirred for 3 h, and then heated and cured at 80°C for 30 min.

[0048] (D) The coil is subjected to an MT test, and the prepared film is assembled with the coil, and the PMMA layer and the silicon wafer are removed to obtain a micro flexible magnetic temperature sensor device.

[0049] Figure 3 This is the SEM image of the magnetic film of the micro-magnetic flexible temperature sensor device prepared in this example.

[0050] Example 2

[0051] according to Figure 1 The flow chart shown is to prepare a micro-magnetic flexible temperature sensor device with a composite material of NiCoMnTi / Cr:

[0052] (A) Fabricate 7 μm / 1 μm thick PI / PMMA on a silicon wafer as the device substrate and sacrificial layer;

[0053] (B) On the flexible substrate surface, the vacuum degree is 8×10 -6 Under the conditions of Pa, Ar gas flux of 100 SCCM, and sputtering power of 60W, a 150nm / 50nm thick NiCoMnTi / Cr layer was magnetron sputtered. The Cr layer was used to strengthen the bonding between the coil and the substrate. The device structure was fabricated by positive resist lithography, and the excess material was removed by lift-off. The surface of the obtained micro-flexible magnetic temperature sensor device was spin-coated with a 2μm thick PI layer as a device encapsulation effect.

[0054] (C) PDMS components A and B were mixed in a mass ratio of 10:1, and 40% by mass of NdFeB was added. The mixture was stirred for 3 h, and then heated and cured at 80°C for 30 min.

[0055] (D) The coil is subjected to an MT test, and the prepared film is assembled with the coil, and the PMMA layer and the silicon wafer are removed to obtain a micro flexible magnetic temperature sensor device.

[0056] Example 3

[0057] according to Figure 1 The flow chart shown below is for preparing a micro-magnetic flexible temperature sensor device with a composite material of NiCoMnIn / Cr:

[0058] (A) Fabricate 7 μm / 1 μm thick PI / PMMA on a silicon wafer as the device substrate and sacrificial layer;

[0059] (B) On the flexible substrate surface, the vacuum degree is 8×10 -6 Under the conditions of Pa, Ar gas flux of 100 SCCM, and sputtering power of 60W, a 150nm / 50nm thick NiCoMnIn / Cr layer was magnetron sputtered. The Cr layer was used to strengthen the bonding between the coil and the substrate. The device structure was fabricated by positive resist lithography, and the excess material was removed by lift-off. The surface of the obtained micro-flexible magnetic temperature sensor device was spin-coated with a 2μm thick PI layer as a device encapsulation effect.

[0060] (C) PDMS components A and B were mixed in a mass ratio of 10:1, and 60% by mass of NdFeB was added. The mixture was stirred for 3 h, and then heated and cured at 80°C for 30 min.

[0061] (D) The coil is subjected to an MT test, and the prepared film is assembled with the coil, and the PMMA layer and the silicon wafer are removed to obtain a micro flexible magnetic temperature sensor device.

[0062] Figure 4 This is the SEM image of the magnetic film of the micro-magnetic flexible temperature sensor device prepared in this example.

[0063] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Other variations and modifications are possible without exceeding the technical solutions described in the claims.

Claims

1. A micro flexible magnetic temperature sensor device, characterized in that: include: Polymer flexible substrates, temperature-sensitive magnetic phase change coils and flexible permanent magnetic composite films, The temperature-sensitive magnetic phase change coil is connected to an electrode, and the temperature-sensitive magnetic phase change coil is encapsulated on the polymer flexible substrate. A flexible permanent magnetic composite film is provided above the temperature-sensitive magnetic phase change coil, and a space for the flexible permanent magnetic composite film to vibrate is provided between the polymer flexible substrate and the flexible permanent magnetic composite film.

2. A micro flexible magnetic temperature sensor device according to claim 1, characterized in that: An iron core is arranged in the middle of the temperature-sensitive magnetic phase change coil. The material of the temperature-sensitive magnetic phase change coil is NiCoMnIn / Cr or NiCoMnTi / Cr. The material of the polymer flexible substrate is polyimide PI.

3. The method for preparing a micro flexible magnetic temperature sensor device according to claim 1, wherein: The following steps are involved: (A) A PMMA layer is fabricated on a silicon wafer as a sacrificial layer, and then a PI layer is fabricated on the PMMA layer as a polymer flexible substrate. (B) depositing a temperature-sensitive magnetic phase change material layer on the substrate surface by magnetron sputtering, annealing, and then patterning the coil using positive photolithography. Excess material is removed by lift-off to obtain a temperature-sensitive magnetic phase change coil. A layer of PI is spin-coated on the temperature-sensitive magnetic phase change coil to obtain a substrate for encapsulating the coil. (C) mixing and stirring the permanent magnetic material and the A and B components of PDMS, and heating and curing the resulting mixture into a film to obtain a flexible permanent magnetic composite film; (D) Assembling the flexible permanent magnetic composite film with the substrate of the encapsulated coil, removing the PMMA layer and the silicon wafer, and obtaining a micro flexible magnetic temperature sensor device.

4. The method for preparing a micro flexible magnetic temperature sensor device according to claim 3, characterized in that: In the step (C), the mass ratio of the A and B components of the PDMS is 10:

1.

5. The method for preparing a micro flexible magnetic temperature sensor device according to claim 3, characterized in that: In the step (A), the substrate and the sacrificial layer are manufactured by spin coating, the thickness of the substrate is 7 μm, and the thickness of the sacrificial layer is 1 μm; In the step (B), the material and thickness of the magnetic phase change material layer deposited by magnetron sputtering are: NiCoMnIn 150nm / Cr 50nm or NiCoMnTi 150nm / Cr 50nm.

6. The method for preparing a micro flexible magnetic temperature sensor device according to claim 5, characterized in that: In the step (A), the length of the polymer flexible substrate is controlled to be ≤2 cm and the width is ≤1.5 cm; In the step (D), the thickness of the obtained micro flexible magnetic temperature sensor device is controlled to be ≤2 mm.

7. The method for preparing a micro flexible magnetic temperature sensor device according to claim 5, characterized in that: In step (C), the permanent magnetic material is NdFeB.

8. The method for preparing a micro flexible magnetic temperature sensor device according to claim 3, characterized in that: In step (B), during the deposition of the temperature-sensitive magnetic phase change material layer, Cr is first deposited to enhance the bonding force between the temperature-sensitive magnetic phase change coil and the polymer flexible substrate, and then the NiCoMnIn layer is deposited.

9. The method for preparing a micro flexible magnetic temperature sensor device according to claim 7, characterized in that: In step (C), the mass ratio of the permanent magnetic material to the mixture is 40% to 60%; The heating and curing process is: heating and curing at 80° C. for 30 minutes.

10. A method for detecting temperature changes in a specific temperature range using a micro flexible magnetic temperature sensor device according to claim 1, characterized in that: The following steps are involved: Selecting a temperature range to be detected, wherein the temperature range includes the temperature at which the phase change material undergoes phase change; applying a voltage to the electrode to cause the temperature-sensitive magnetic phase change coil to generate an electromagnetic induction magnetic field; When the temperature changes to a temperature at which the phase change material produces a phase change, the magnetic field generated by the temperature-sensitive magnetic phase change coil changes, and the temperature change is fed back by the vibration change of the flexible permanent magnetic composite film.

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