CN112535486B

CN112535486B - SMP-based spiral electroencephalogram monitoring device and preparation method thereof

Info

Publication number: CN112535486B
Application number: CN202011011353.3A
Authority: CN
Inventors: 冯雪; 王宙恒; 张迎超
Original assignee: Tsinghua University
Current assignee: Tsinghua University
Priority date: 2020-09-23
Filing date: 2020-09-23
Publication date: 2021-07-02
Anticipated expiration: 2040-09-23
Also published as: CN112535486A

Abstract

The invention provides a SMP-based spiral electroencephalogram monitoring device and a preparation method thereof. The device has a bionic sandwich structure, sequentially comprises a signal acquisition device, an intermediate layer SMP, a heating device and a bottom layer SMP along the thickness direction from top to bottom when the device is in a flattening state, wherein the intermediate layer SMP and the bottom layer SMP are made of materials with reconfigurable permanent shapes, the signal acquisition device and the heating device are patterned metal films, and when voltage is applied to the heating device, the intermediate layer SMP and the bottom layer SMP gradually recover to the permanent shapes along with the temperature exceeding the transition temperature of the intermediate layer SMP and the bottom layer SMP, the spiral shape of the electroencephalogram monitoring device expands, and in the working state, the spiral radius of the electroencephalogram monitoring device is larger than the radius of the tested auditory canal, so that the signal acquisition device is in close contact with the inner side of the tested auditory canal.

Description

SMP-based spiral electroencephalogram monitoring device and preparation method thereof

Technical Field

The invention relates to the technical field of medical detection, in particular to a spiral bionic sandwich structure monitoring electroencephalogram device based on a Shape Memory Polymer (SMP) and a preparation method thereof, wherein the monitoring electroencephalogram device can realize spiral climbing through active heating, so that electroencephalogram signals in auditory canals can be monitored in real time.

Background

The auditory meatus is an area close to the temporal region, and the auditory meatus can go deep into the auditory meatus to monitor electroencephalogram signals, so that the auditory meatus has very important reference significance for patients with tumors in the temporal region and the like. Most of the previous works rely on the integration of electrodes and supports such as earplugs, so as to achieve the purpose of testing, but the test has obvious disadvantages: because the support is inserted into the auditory canal, the tested person cannot communicate with the outside at the same time, and obvious blocking feeling and uncomfortable feeling exist, so that the introduced complex emotional fluctuation irrelevant to tasks brings great difficulty to subsequent signal analysis.

Shape Memory Polymer (SMP) is a new type of functional polymer material, and is a new branch point for the research, development and application of current polymer materials. However, there is no report of any SMP applied to monitor electroencephalographic devices. SMP has both plastic and rubber properties. Molecular design and molecular structure adjustment of SMP can impart a certain shape (initial state) under certain conditions. When external conditions change, the SMP can change shape accordingly and be fixed (morphed). The SMP reverts reversibly to an initial state if the external environment changes again in a particular way and regularly. At this point, the cycle of memory initial state-fixed morphism-recovery initial state is completed. Shape memory effects in SMP derive from their intrinsic two-phase structure, i.e. reversible phase and stationary phase. For a thermoresponsive SMP, a reversible phase in the molecular network is activated upon heating above the SMP transition temperature. When the SMP is subjected to an external force, the molecular network structure deforms, the external force is maintained, the SMP is cooled to a temperature below the transition temperature, the reversible phase freezes, and the material remains in a "temporary shape". The external force is removed and the SMP is again heated above its transition temperature, activated by the frozen reversible phase, and returns to its "permanent shape" under the action of entropy elasticity. While the permanent shape of conventional thermoset SMPs is mostly dependent on the shape of the mold used in the preparation, reference 1 describes an SMP system with a reconfigurable permanent shape, in which researchers introduce reversible dynamic covalent bonds into the SMP polymer network, breaking through the limitations of the mold on the setting of the permanent shape of the SMP.

Documents of the prior art

Reference to the literature

Reference 1: zhao Q, Zou W, Luo Y, et al. shape memory polymer network with thermal degradation elasticity and plasticity. science Advances.2016,2: e150129

Disclosure of Invention

The invention is made in view of the problems in electroencephalogram monitoring, and aims to enable a tested object to communicate with the outside while performing electroencephalogram monitoring, and alleviate or overcome the blocking feeling and discomfort feeling when a monitoring electroencephalogram device is inserted into an ear canal, thereby reducing the influence of irrelevant emotional fluctuation on signal analysis.

The invention provides a SMP-based spiral electroencephalogram monitoring device, which has a bionic sandwich structure, the electroencephalogram monitoring device comprises a signal collecting device, a middle layer SMP, a heating device and a bottom layer SMP from top to bottom in sequence along the thickness direction when the electroencephalogram monitoring device is in a flattening state, wherein the middle layer SMP and the bottom layer SMP are made of materials with reconfigurable permanent shapes, the signal acquisition device and the heating device are both patterned metal films, and when a voltage is applied to the heating means, as the temperature exceeds the transition temperature of the intermediate layer SMP and the bottom layer SMP, the middle layer SMP and the bottom layer SMP gradually return to a permanent shape, the spiral shape of the monitoring brain electric device expands, under operating condition, the spiral radius of monitoring brain electrical equipment is greater than the auditory canal radius of being tried, makes the acquisition signal device with the auditory canal inboard in close contact with of being tried.

The invention also provides a preparation method of the SMP-based spiral monitoring electroencephalogram device, which comprises the following steps:

forming a signal acquisition device and a heating device by patterning the metal film;

integrating the signal acquisition device and the heating device into a bionic sandwich structure based on SMP (symmetrical multi-processing) by utilizing a transfer printing process, wherein the bionic sandwich structure is the signal acquisition device/a middle layer SMP/the heating device/a bottom layer SMP;

heating and softening the bionic sandwich structure, winding the bionic sandwich structure on a first rod body with a first diameter, and then carrying out heat treatment to deform the molecular grid structures of the intermediate layer SMP and the bottom layer SMP and memorize the permanent shapes of the intermediate layer SMP and the bottom layer SMP;

and cooling the bionic sandwich structure to the temperature below the transition temperature of the middle layer SMP and the bottom layer SMP, taking down the bionic sandwich structure from the first rod body, heating and softening to enable the sandwich structure to be wound on a second rod body with the second diameter smaller than the first diameter, fixing the middle layer SMP and the bottom layer SMP into a temporary shape, taking down the second rod body from the bionic sandwich structure, and obtaining the spiral monitoring electroencephalogram device.

According to the SMP-based spiral monitoring electroencephalogram device and the preparation method thereof, the tested electroencephalogram can be communicated with the outside while being monitored, the discomfort of the tested electroencephalogram when the device is inserted into an auditory canal is greatly relieved, and the electroencephalogram signal can be more accurately analyzed.

Drawings

Other features and aspects of the present invention will become apparent from the following detailed description of exemplary embodiments, which proceeds with reference to the accompanying drawings.

FIG. 1 is a cross-sectional view of a monitoring brain electrical device according to one embodiment of the present invention in a flattened state.

Fig. 2 is a plan view of a signal acquisition device in a monitoring electroencephalograph according to an embodiment of the present invention.

Fig. 3 is a plan view of a heating device in a monitoring brain device according to an embodiment of the present invention.

FIG. 4 is a cross-sectional view of a monitoring brain electrical device according to another embodiment of the present invention in a flattened state.

FIG. 5 is a schematic diagram of a monitoring brain electrical device according to an embodiment of the present invention positioned in the ear canal.

FIG. 6 shows a schematic diagram of a monitoring brain electrical device according to an embodiment of the present invention in an operating state, positioned in an ear canal.

Description of the reference numerals

1 monitoring electroencephalogram device

10 Signal acquisition device

20 Dimethicone (PDMS)

30 intermediate layer SMP

40 heating device

50 bottom SMP

101 electrode

102 signal line

103 lead terminal

401 resistance

402 lead terminal

2 auditory canal

Detailed Description

Exemplary embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood that the detailed description is intended only to teach one skilled in the art how to practice the invention, and is not intended to be exhaustive or to limit the scope of the invention.

FIG. 1 is a cross-sectional view of a monitoring brain electrical device 1 according to one embodiment of the present invention in a flattened state, illustrating the sandwich-like layered structure of the monitoring brain electrical device 1. As shown in fig. 1, the electroencephalogram monitoring device 1 sequentially comprises, from top to bottom (from outside to inside) in the thickness direction: the signal acquisition device 10, the intermediate layer SMP 30, the heating device 40 and the bottom layer SMP50 may each have a thickness of 7 μm to 13 μm (e.g., 10 μm), 80 μm to 120 μm (e.g., 100 μm), 7 μm to 13 μm (e.g., 10 μm) and 80 μm to 120 μm (e.g., 100 μm), respectively.

In the monitoring brain electrical device 1 of this embodiment, two SMPs of which the permanent shape is reconfigurable are used, namely a middle SMP 30 (softer) and a bottom SMP50 (harder). The two SMPs have different transition temperatures and different elastic moduli, wherein the transition temperature of the harder bottom SMP50 serving as a supporting structure is 45 ℃ for example, and the elastic modulus is in the order of MPa, and mainly plays a role in supporting similar to a framework in the structure; the softer intermediate layer SMP 30 has a transition temperature of, for example, 37 c and an elastic modulus of the order of kPa, and mainly plays a role in facilitating transfer and handling in the structure. When the transition temperature is reached, the viscosity of the SMP (i.e., the middle layer SMP 30) is increased, so that the signal acquisition device 10 and the heating device 40 can be integrated without auxiliary liquid such as other glue, and the overall deformation of the electroencephalograph device 1 can be assisted to some extent. It should be noted that although an example using two types of permanently reconfigurable SMPs is shown in this embodiment, the present invention is not limited thereto. The present invention may be implemented using only one permanent reconfigurable SMP, or using other permanent reconfigurable SMPs.

In this embodiment, the signal collecting device 10 (see fig. 2) and the heating device 40 (see fig. 3) are patterned metal thin films and each sequentially include polyimide (i.e., PI), gold (Au), chromium (Cr), and PI from top to bottom in a thickness direction, where PI has a thickness of 3 μm to 5 μm, Au has a thickness of 100nm to 200nm, and Cr may have a thickness of 10 nm. In other embodiments, Ti may also be used instead of Cr. The patterning of the signal acquisition device 10 and the heating device 40 ensures its flexibility and stretchability during deformation. As shown in fig. 2, the signal acquisition device 10 has a plurality of electrodes (i.e., acquisition ends) 101, so that the electroencephalogram monitoring can be performed by a multi-point acquisition (multi-point single measurement) (the signal acquisition device is not limited to such a pattern and connection). The electrode 101 is connected to a lead terminal 103 via a signal line 102. Since the portion of the signal acquisition device 10 contacting the skin needs to expose the electrode, there is no PI package above the electrode 101, that is, the signal acquisition device 10 includes only Au, Cr and PI in sequence from top to bottom at the electrode 101 along the thickness direction, and the signal line 102 is covered with PI. As shown in fig. 3, in the heating device 40, the pattern of the resistor 401 is a quincunx, but the shape of the resistor 401 is not limited to the quincunx, and may be any shape such as a circle, a square, or a star. A plurality of resistors 401 are connected in series and connected to a power source through lead terminals 402. When designing the shape and number of the resistors 401, it is necessary to consider the safety of the electroencephalogram device 1 to the human body when being inserted into the ear canal, so as to ensure that the total resistance of the heating device 40 is 200 Ω -400 Ω (for example, about 300 Ω) by applying 6V-10V dc voltage to the heating device 40, which can provide the required temperature of about 40-50 ℃ for the deformation of the SMP.

FIG. 4 illustrates a cross-sectional view of a monitoring brain electrical device according to another embodiment of the present invention in a flattened state. The difference from the above-described embodiment is that, in the present embodiment, in order to ensure that the monitoring electroencephalogram apparatus 1 does not feel hot when in contact with the skin, the monitoring electroencephalogram apparatus 1 further includes PDMS 20 as a heat absorbing layer (heat insulating layer). Other structures in the present embodiment are the same as those in the above embodiment, and therefore, the description thereof is omitted. The PDMS 20 is located between the signal acquisition device 10 and the intermediate layer SMP 30 in the thickness direction, and may have a thickness of 5 μm to 10 μm. Optionally, a heat absorbing powder may also be added to the PDMS 20 to further ensure that the subject does not feel uncomfortable due to the heating of the monitoring brain electrical device 1.

FIG. 5 is a schematic diagram of a monitoring brain electrical device 1 according to an embodiment of the present invention located in the ear canal 2. As shown in FIG. 5, the monitoring brain electric device 1 according to this embodiment is in the shape of a small spiral with a diameter of 3 mm. It should be noted that, although the diameter shown in the present embodiment is 3mm, the present invention is not limited thereto as long as the diameter is ensured to be smaller than the narrowest diameter of the ear canal. This small spiral shape corresponds to the state in which the SMP is in a "temporary shape" at which time the reversible phase of the SMP is frozen. When the monitoring brain electric device 1 having a small spiral shape is inserted into the auditory canal 2 of a subject and a direct current voltage of 6V to 10V is applied to the heating means 40, the frozen reversible phase is activated as the temperature exceeds the transition temperature of the intermediate layer SMP 30 and the bottom layer SMP50, so that the intermediate layer SMP 30 and the bottom layer SMP50 gradually recover from the "temporary shape" to the "permanent shape" thereof under the action of entropy elasticity. Accordingly, the monitoring brain electric device 1 gradually expands from the small spiral shape to the large spiral shape. As shown in FIG. 6, the monitoring brain electrical device 1 according to the embodiment of the present invention located in the ear canal 2 is in a large spiral shape with a diameter of 8mm (first diameter) in an operating state. It should be noted that, although the diameter shown in the present embodiment is 8mm, the present invention is not limited thereto as long as the diameter is ensured to be larger than the widest diameter of the ear canal. This large spiral shape corresponds to a state where the SMP is in a "permanent shape", and the monitoring electroencephalogram device 1 works in this large spiral shape (electroencephalogram monitoring). In a working state, the spiral radius of the large spiral-shaped electroencephalogram monitoring device 1 is larger than the radius of the auditory canal 2, so that the signal acquisition device 10 of the electroencephalogram monitoring device 1 can be ensured to be in close contact with the inner side of the auditory canal 2. After the direct-current voltage is removed, the whole structure of the monitoring electroencephalogram device 1 is cooled, the middle layer SMP 30 and the bottom layer SMP50 are hardened at the moment, the whole structure of the monitoring electroencephalogram device 1 is supported on the inner side of the auditory canal 2, and the tested electroencephalogram signal is collected through the signal collecting device 10. Because under operating condition, monitoring brain electric installation 1 is the spiral shape, and the cavity or the fretwork structure of spiral make monitoring brain electric installation 1's gas permeability good, and the quilt is tried to communicate with the external world at any time to because SMP is biocompatible material, also can not bring the discomfort to the comparatively sensitive skin in the duct 2. Therefore, the monitoring brain electric device 1 according to the embodiment of the present invention greatly relieves the discomfort of the subject when a foreign object is inserted into the ear canal 2 at the time of test, and reduces the influence of the irrelevant emotional fluctuation on the signal analysis.

After the signal monitoring is finished, the heating device is applied with the direct current voltage of 6V-10V again, so that the middle layer SMP 30 and the bottom layer SMP50 can be softened, and at the moment, the monitoring brain electric device 1 is taken out from the tested auditory canal.

It should be understood that the ear canal 2 is drawn as a straight tube for exemplary purposes only. It will be appreciated by those skilled in the art that due to the helical shape of the monitoring brain electrical device 1, and in particular the helical shape of adjacent turns spaced apart, it may fit properly in ear canals that are not straight in nature and vary in diameter.

The method of manufacturing the monitoring brain electrical device 1 is explained in detail below. The method comprises the following steps:

(1) preparation of patterned Signal Collection device 10 and heating device 40

As mentioned above, the signal acquisition device 10 and the heating device 40 are both PI (first PI)/Au/Cr/PI (second PI) structures, and thus the manufacturing method thereof is substantially the same. Firstly, a silicon wafer is selected as a hard substrate, polymethyl methacrylate (PMMA) is spin-coated on the substrate as a sacrificial layer, and the substrate is heated to be formed into a film. And coating a polyimide precursor PAA solution (rotating speed of 5000rpm and duration of 40s) on the sacrificial layer, and heating and curing in stages to obtain a second PI film (thickness of 3-5 μm). Then, a metal layer material is grown on the prepared PI film by using a film growth technique (e.g., evaporation or sputtering) to form a metal film. The metal film may include a first metal layer and a second metal layer, and the second metal layer is used to bond the first metal layer to the second PI film. The first metal layer may be a metal with good ductility, such as Au, and the thickness of the first metal layer may be 100nm to 200 nm. The second metal layer is mainly used for bonding the first metal layer and the second PI film, so that the second metal layer can be one of Cr and Ti, and the thickness of the second metal layer can be 5nm-20 nm. For example, when the second metal layer is Cr, the thickness thereof may be 10 nm.

Next, the metal thin film is patterned using a photolithography method or a photolithography mask lift-off method. The electrode main body can be made into a net structure through patterning (refer to fig. 2 and 3), and the PI film is etched by using the net structure as a mask and adopting a reactive ion etching technology, so that the flexible extensible device respectively made of Au/Cr/PI/PMMA from top to bottom can be obtained.

And finally, preparing a photosensitive PI (first PI) on the uppermost layer of the Au/Cr/PI/PMMA structure in a spin coating mode, and forming a corresponding pattern in an alignment mode to manufacture the flexible and extensible signal acquisition device 10 or the heating device 40. For the signal acquisition device 10, the acquisition end (i.e. the electrode 101) needs to be exposed, so that the single point of the electrode 101 still is Au/Cr/PI/PMMA from top to bottom, and the rest of patterns are covered by PI, which is sequentially PI/Au/Cr/PI/PMMA from top to bottom; for the heating device 40, it is completely packaged with PI to ensure its reliability, sequentially PI/Au/Cr/PI/PMMA from top to bottom.

(2) Bionic sandwich structure formed by transfer printing

The transfer step is described by taking the bionic sandwich structure as the signal acquisition device 10/PDMS 20/middle SMP 30/heating device 40/bottom SMP50 structure as an example. First, a sacrificial layer PMMA is etched in acetone, and the signal pickup device 10 and the heating device 40 are respectively transferred onto a flexible substrate (e.g., PDMS), and the ACF lines are respectively soldered to the lead terminals 103 and 402. The heating device 40 is again transferred to the softer SMP that is more tacky after heating, which will be the middle layer, and then the harder SMP, which will be the bottom layer, is integrated on the opposite side of the heating device 40 from the side where the softer SMP is integrated, forming a sandwich structure (softer SMP/heating device 40/harder SMP). And transferring the thin PDMS 20 (the thickness is 5-10 μm), so that the thin PDMS is integrated with the side, which is not integrated with the heating device 40, of the soft SMP with larger viscosity after heating, and transferring the signal acquisition device 10 to the thin PDMS 20 to form the layered structure of the electroencephalogram monitoring device 1. As shown in fig. 4, the layered structure includes, from top to bottom in the thickness direction, a signal acquisition device 10, PDMS 20, an intermediate layer SMP 30 (softer SMP), a heating device 40, and a bottom layer SMP50 (harder SMP).

It should be noted that, when the bionic sandwich structure shown in fig. 1 and not including the PDMS 20 is prepared, the step of transferring the thin PDMS 20 is only required to be omitted, and the signal acquisition device 10 is directly transferred to the side of the intermediate layer SMP 30 where the heating device 40 is not integrated.

(3) Large spiral shape of memory signal acquisition device 10/PDMS 20/middle layer SMP 30/heating device 40/bottom layer SMP50 structure (corresponding to SMP initial state, namely permanent shape)

The signal acquisition device 10/PDMS 20/middle layer SMP 30/heating device 40/bottom layer SMP50 structure was heat softened (50 ℃) and wound on a Teflon rod with a diameter of 8mm (first diameter) with both ends fixed with PI tapes. The structure is placed in an oven and heated at 150 ℃ for 40min and then at 175 ℃ for 15min, so that the structure forms the monitoring brain electric device 1 with a large spiral shape as shown in fig. 6. At this time, the reversible phase in the molecular network is activated, and the molecular network structure of the SMP is deformed when an external force is applied thereto (e.g., bonded to a teflon rod having a diameter of 8mm in the present embodiment).

(4) Cooling below the transition temperature of the SMP, fixing the acquisition device 10/PDMS 20/intermediate SMP 30/heating device 40/bottom SMP50 structure to a small spiral shape (corresponding to the deformed, i.e. temporary shape of the SMP)

After the signal acquisition device 10/PDMS 20/middle layer SMP 30/heating device 40/bottom layer SMP50 structure is naturally cooled, the structure is taken down from a Teflon rod with the diameter of 8mm, softening is carried out in hot water at 50 ℃, then the softened structure is wound on the Teflon rod with the diameter of 3mm, and two ends of the structure are respectively fixed by PI adhesive tapes. After the structure is cooled, the PI tape is torn off, the structure is taken off from the teflon rod with the diameter of 3mm (the second diameter), at this time, the reversible phase is frozen, the SMP is kept in a temporary shape, and the small spiral monitoring electroencephalogram device 1 shown in fig. 5 is obtained.

When the monitoring electroencephalogram device 1 is required to be used for testing, the monitoring electroencephalogram device 1 is only required to be inserted into an auditory canal, a direct-current voltage of 6V-10V is applied, and the temperature of 40-50 ℃ is obtained by using the heating device 40, so that the SMP reaches the temperature above the transition temperature. At this time, the SMP can gradually recover its permanent shape (initial state), and accordingly, the monitoring electroencephalogram device 1 also expands from a small spiral shape to a large spiral shape. After cooling (stopping applying voltage), the monitoring electroencephalogram device 1 is self-supporting, and the signal acquisition device 10 can be tightly attached to the inner side of the auditory canal, so that effective electroencephalogram monitoring is carried out.

The invention has at least one of the following advantages:

(1) the signal acquisition device 10 and the heating device 40 are patterned metal films to ensure flexibility and stretchability during deformation.

(2) The monitoring brain electric device 1 is in a spiral shape in a working state, the air permeability of the monitoring brain electric device 1 is good due to the spiral hollow structure, the tested brain electric device can communicate with the outside at any time, the SMP is made of a biocompatible material, discomfort can not be brought to sensitive skin in an auditory canal, and therefore the influence of irrelevant mood fluctuation on signal analysis is reduced.

Of course, the present invention is not limited to the above-described embodiments, and those skilled in the art can make various modifications to the above-described embodiments of the present invention without departing from the scope of the present invention under the teaching of the present invention.

Claims

1. The spiral electroencephalogram monitoring device based on the shape memory polymer is characterized by having a bionic sandwich structure, and when the electroencephalogram monitoring device (1) is in a flattening state, the electroencephalogram monitoring device sequentially comprises a signal collecting device (10), a middle-layer shape memory polymer (30), a heating device (40) and a bottom-layer shape memory polymer (50) from top to bottom along the thickness direction, wherein,

the middle layer shape memory polymer (30) and the bottom layer shape memory polymer (50) are made of a permanent shape reconfigurable material,

the signal acquisition device (10) and the heating device (40) are both patterned metal films, and

when voltage is applied to the heating device (40), the transition temperature of the middle layer shape memory polymer (30) and the bottom layer shape memory polymer (50) is exceeded along with the temperature, the middle layer shape memory polymer (30) and the bottom layer shape memory polymer (50) gradually recover to a permanent shape, the spiral shape of the electroencephalogram monitoring device (1) expands, and in a working state, the spiral radius of the electroencephalogram monitoring device (1) is larger than the radius of the tested auditory canal, so that the signal acquisition device (10) is in close contact with the inner side of the tested auditory canal.

2. The device of claim 1, wherein the middle layer shape memory polymer (30) and the bottom layer shape memory polymer (50) are of different materials, wherein the middle layer shape memory polymer (30) is of a softer material than the bottom layer shape memory polymer (50), the transition temperature of the middle layer shape memory polymer (30) is less than the transition temperature of the bottom layer shape memory polymer (50), the modulus of elasticity of the middle layer shape memory polymer (30) is on the order of kPa, and the modulus of elasticity of the bottom layer shape memory polymer (50) is on the order of MPa.

3. The device according to claim 1 or 2, wherein said device (1) further comprises polydimethylsiloxane (20), said polydimethylsiloxane (20) being located between said signal acquisition device (10) and said intermediate layer shape memory polymer (30) in said thickness direction, and said polydimethylsiloxane (20) having a thickness of 5-10 μm.

4. The electroencephalograph for monitoring according to claim 1 or 2, wherein the thickness of the signal acquisition device (10), the middle layer shape memory polymer (30), the heating device (40), and the bottom layer shape memory polymer (50) are 7 μ ι η -13 μ ι η, 80 μ ι η -120 μ ι η, 7 μ ι η -13 μ ι η, and 80 μ ι η -120 μ ι η, respectively.

5. The electroencephalograph monitoring device according to claim 1 or 2, wherein each of the signal acquisition device (10) and the heating device (40) comprises, from top to bottom in the thickness direction, a first polyimide, a first metal layer, a second metal layer and a second polyimide in sequence, and the second metal layer is used for bonding the first metal layer and the second polyimide.

6. The electroencephalograph for monitoring of claim 5, wherein the first metal layer is gold having a thickness of 100nm to 200nm, and the second metal layer is chromium or titanium having a thickness of 5nm to 20 nm.

7. The device for monitoring brain electricity according to claim 5, wherein the signal collecting device (10) includes a plurality of electrodes (101), and at the electrodes (101), the signal collecting device (10) includes only a first metal layer, a second metal layer and a second polyimide in sequence from top to bottom along the thickness direction.

8. The electroencephalograph for monitoring according to claim 1 or 2, wherein the direct current voltage applied to said heating device (40) is 6V-10V, said heating device (40) comprises a plurality of resistances (401), and the total resistance of said heating device (40) is 200 Ω -400 Ω.

9. A preparation method of a spiral monitoring electroencephalogram device based on a shape memory polymer is characterized by comprising the following steps:

forming a signal collecting device (10) and a heating device (40) by patterning the metal thin film;

integrating the signal acquisition device (10) and the heating device (40) into a bionic sandwich structure based on the shape memory polymer by utilizing a transfer printing process, wherein the bionic sandwich structure comprises the signal acquisition device (10), a middle-layer shape memory polymer (30), the heating device (40) and a bottom-layer shape memory polymer (50) which are sequentially arranged;

heating and softening the bionic sandwich structure, winding the bionic sandwich structure on a first rod body with a first diameter, and then carrying out heat treatment to deform the molecular mesh structures of the middle-layer shape memory polymer (30) and the bottom-layer shape memory polymer (50) and memorize the permanent shapes of the middle-layer shape memory polymer (30) and the bottom-layer shape memory polymer (50);

and cooling the bionic sandwich structure to the temperature below the transition temperature of the middle layer shape memory polymer (30) and the bottom layer shape memory polymer (50), taking down the bionic sandwich structure from the first rod body, heating and softening the bionic sandwich structure to enable the bionic sandwich structure to be wound on a second rod body with a second diameter smaller than the first diameter, enabling the middle layer shape memory polymer (30) and the bottom layer shape memory polymer (50) to be fixed into a temporary shape, and taking down the bionic sandwich structure from the second rod body to obtain the spiral electroencephalogram monitoring device.

10. The method for preparing a spiral electroencephalograph for monitoring according to claim 9, wherein in the transfer process, polydimethylsiloxane (20) is transferred to the side of the middle-layer shape memory polymer (30) where the heating device (40) is not integrated, and then the signal acquisition device (10) is transferred to the side of the polydimethylsiloxane (20) where the middle-layer shape memory polymer (30) is not integrated, so as to obtain a bionic sandwich structure with the structure of the signal acquisition device (10), the polydimethylsiloxane (20), the middle-layer shape memory polymer (30), the heating device (40) and the bottom-layer shape memory polymer (50) which are sequentially arranged.