CN114234791B - Preparation method of composite film strain sensor based on dropping deposition - Google Patents
Preparation method of composite film strain sensor based on dropping deposition Download PDFInfo
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- CN114234791B CN114234791B CN202111542138.0A CN202111542138A CN114234791B CN 114234791 B CN114234791 B CN 114234791B CN 202111542138 A CN202111542138 A CN 202111542138A CN 114234791 B CN114234791 B CN 114234791B
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- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
- G01B7/16—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring the deformation in a solid, e.g. by resistance strain gauge
- G01B7/18—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring the deformation in a solid, e.g. by resistance strain gauge using change in resistance
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Abstract
The invention discloses a preparation method of a composite film strain sensor based on drop deposition, which comprises the following steps: s1: adding polyvinyl alcohol powder into distilled water to completely dissolve polyvinyl alcohol to obtain a uniform polyvinyl alcohol aqueous solution; s2: completely mixing the carbon black solution with the polyvinyl alcohol solution to obtain a uniform carbon black/polyvinyl alcohol solution; s3: removing air mixed in the solution to obtain pure carbon black/polyvinyl alcohol solution; s4: putting the obtained carbon black/polyvinyl alcohol solution into a micro-coater, and coating the solution on a substrate by adopting a droplet deposition method; s5: and heating and curing the carbon black/polyvinyl alcohol film to obtain the carbon black/polyvinyl alcohol composite film strain sensor. According to the invention, through a liquid drop deposition mode, the uniformity of the film can be ensured, the controllability of the thickness and the size of the film can be improved, and the loss of materials can be reduced.
Description
Technical Field
The invention relates to the technical field of strain sensor preparation, in particular to a preparation method of a composite film strain sensor based on drop deposition.
Background
The strain sensor is a sensing device which converts the deformation of a measured object caused by external stimulation signals such as force, vibration and the like into other electric signals. Conventional strain sensors on the market are mainly made of rigid materials such as semiconductors, ceramics, metals and the like, and have ideal sensitivity, but the conventional strain sensors have high cost and poor flexibility, and the sensitivity is reduced along with the increase of applied strain. And the flexible strain sensor has better stretchability and can adapt to larger deformation. This has led to extensive research and popularization of flexible strain sensors in the fields of human-machine interaction, health monitoring, wearable devices, artificial skin, and prosthetic limbs, which have received much attention in recent years.
Under the background, the mode of preparing the flexible composite film strain sensor by mixing the conductive filler and the non-conductive polymer is developed, and the strain sensor prepared by the mode of the composite material has the advantages of good flexibility, free bending, thin thickness, high sensitivity and the like.
However, for composite thin film strain sensors, in addition to the choice of materials, the manner of film formation is also important. The film formation method determines the uniformity, flatness, thickness and the like of the thin film, which are all closely related to the performance of the sensor.
The current method for preparing the composite film is mainly a spraying method, wherein the spraying method is that a conductive dispersion is placed in a spray gun, then compressed air atomizes the dispersion into small droplets, the small droplets are deposited on a preheated substrate under the action of air flow, and a conductive film is formed after drying; the bar coating method is to place conductive dispersion ink on a substrate and then roll a bar at a certain speed to disperse the ink, thereby forming a uniform conductive film; the drop coating method is a process of directly dropping a liquid to be coated on a target substrate, and drying the liquid to form a film; in the process of preparing a thin film by the spin coating method, a substrate is generally rotated on a turntable which rotates at a high speed, and a dispersion liquid placed on the substrate is diffused to the entire substrate area due to the presence of a centrifugal force, thereby forming a thin film; the solution casting method is that a proper amount of prepared solution is poured on a substrate to enable the solution to be uniformly spread on the surface of the substrate, and then the solution is heated to enable the solvent to be completely evaporated to form a film; the vapor deposition method is a technique of vaporizing a material source and depositing it on a substrate surface to form a thin film.
The spraying method has simple equipment, is convenient to operate, can realize large-area production, but has poor uniformity of the prepared film; the bar coating method is suitable for mass production, but it requires a dispersion liquid having a high viscosity and a large surface tension; in the operation process of the dripping coating method, nano particles are easy to agglomerate, and the coffee ring effect is easy to occur after drying, so that the uniformity of the film is influenced; the thin film area that the spin-coating method can prepare is limited, and the thickness of the thin film can not be controlled; the film prepared by the solution casting method has large intermolecular distance, loose structure, low strength, high production cost, large energy consumption and low production speed; the film prepared by the deposition method has uniform texture, but has the defects of strict preparation conditions, high equipment price and low efficiency. Therefore, in the existing film preparation methods, a film forming method which is low in cost, simple and easy to operate and controllable in film size and thickness is not provided.
Disclosure of Invention
In order to solve at least or partially the above problems, a method for manufacturing a composite thin film strain sensor based on droplet deposition is provided, and by means of droplet deposition, the uniformity of a thin film can be guaranteed, meanwhile, the controllability of the thickness and the size of the thin film can be improved, and the loss of materials can be reduced.
In order to achieve the purpose, the invention provides the following technical scheme:
the invention relates to a preparation method of a composite film strain sensor based on dropping deposition, which comprises the following steps:
s1: adding polyvinyl alcohol powder into distilled water to completely dissolve polyvinyl alcohol to obtain a uniform polyvinyl alcohol aqueous solution;
s2: completely mixing the carbon black solution and the polyvinyl alcohol solution to obtain a uniform carbon black/polyvinyl alcohol solution;
s3: removing air mixed in the solution to obtain pure carbon black/polyvinyl alcohol solution;
s4: putting the obtained carbon black/polyvinyl alcohol solution into a micro-coater, and coating the solution on a substrate by adopting a droplet deposition method;
s5: and heating and curing the carbon black/polyvinyl alcohol film to obtain the carbon black/polyvinyl alcohol composite film strain sensor.
In a preferred embodiment of the present invention, in the step S2, the step of completely mixing the carbon black solution and the polyvinyl alcohol solution comprises: adding the carbon black solution into the prepared polyvinyl alcohol aqueous solution, putting the mixed solution into a planetary centrifugal mixer, stirring and mixing, carrying out ultrasonic treatment in an ultrasonic cleaning machine, taking out and stirring for 10 minutes.
As a preferred embodiment of the present invention, in the step S3, the step of removing air mixed in the solution comprises: and (3) putting the carbon black/polyvinyl alcohol solution obtained in the step (S2) into a vacuum drying oven for vacuum suction treatment.
In a preferred embodiment of the present invention, in the step S1, the step of completely dissolving the polyvinyl alcohol comprises: heated to 90 ℃ and stirred at this temperature for 20 minutes.
As a preferred embodiment of the present invention, in the step S4, the droplet deposition method includes: in a non-contact mode, the coating device is not in contact with the substrate, only the liquid drops are in contact with the substrate to form liquid drop points, and the positions of the deposited liquid drops can be determined through software control, so that the pattern of the composite film is manufactured.
Compared with the prior art, the invention has the following beneficial effects:
the preparation method of the composite film strain sensor based on droplet deposition can be completed by only using one micro-coater and a computer, and equipment is simple.
The method has the advantage of simple operation, since the droplets of the polymer solution are deposited on the substrate without contact and the position of the droplet deposition is controlled by a computer.
The needle point of the applicator is very small, so the size of the generated liquid drop is very small, the micron-sized liquid drop can be ensured, the material can be effectively prevented from overflowing the designed shape and size, the size and the shape of the film can be accurately mastered, the waste of the material is reduced, and the preparation cost is reduced.
The conductive film prepared by adopting a droplet deposition method can reach a very small thickness, so that the prepared strain sensor has a higher strain coefficient under a very small strain.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:
FIG. 1 is a schematic diagram illustrating a method for preparing a thin film based on droplet deposition according to the present invention;
FIG. 2 is a diagram of a deposition mechanism of a droplet deposition method according to the present invention;
FIG. 3 is a graph showing the size of a droplet point according to an embodiment of the present invention;
FIG. 4 is an optical image of a composite film according to an embodiment of the present invention;
FIG. 5 is a graph of a composite film strain-resistance test according to an embodiment of the present invention;
in the figure: 1 is the tip of the micro-applicator, 2 is the complex solution, and 3 is the substrate.
Detailed Description
The preferred embodiments of the present invention will be described in conjunction with the accompanying drawings, and it should be understood that they are presented herein only to illustrate and explain the present invention and not to limit the present invention. Wherein like reference numerals refer to like parts throughout.
In addition, if a detailed description of the known art is not necessary to show the features of the present invention, it is omitted.
Example 1
As shown in FIG. 1, the present invention provides a method for preparing a composite thin film strain sensor based on droplet deposition, wherein liquid forms spherical droplets at the tip of a micro-applicator under the action of surface tension and intermolecular attraction. As shown in fig. 1-1, the micro-applicator is moved downward so that the droplets contact the substrate, but the applicator does not contact the substrate. It can be seen from fig. 1-2 that when the applicator is removed, a portion of the drop from the tip is on the substrate and a portion remains on the tip.
As shown in fig. 2-1, 2-2, and 2-3, the moving micro-applicator deposits two droplets in succession. As can be seen from fig. 2-4, there is an overlap between the two deposited droplet dots. Since the liquid has fluidity, the space between the molecules at the interface of the liquid droplet at the overlapping portion is small, and the liquid molecules inside the liquid droplet attract each other. Meanwhile, under the action of surface tension, the overlapped droplet points are fused to form a new droplet point, as shown in fig. 2-5, and a composite film is finally formed.
1g of polyvinyl alcohol was weighed into a beaker, 15ml of distilled water was added, heated to 90 ℃ and stirred at this temperature for 20 minutes to completely dissolve the polyvinyl alcohol, giving a uniform aqueous polyvinyl alcohol solution.
Weighing 4g of a 10% CB carbon black solution, adding the CB carbon black solution into a prepared polyvinyl alcohol aqueous solution, placing the carbon black/polyvinyl alcohol mixed solution into a centrifugal mixer, stirring for 10 minutes, placing the centrifugal mixer into an ultrasonic cleaning machine, carrying out ultrasonic treatment for 60 minutes at the frequency of 40kHz, taking out the mixed solution, and stirring for 10 minutes to completely mix the carbon black solution and the polyvinyl alcohol solution to obtain a uniform carbon black/polyvinyl alcohol solution.
And putting the carbon black/polyvinyl alcohol solution obtained in the second step into a vacuum drying oven, and performing vacuum suction for 60 minutes to obtain pure carbon black/polyvinyl alcohol solution.
The resulting carbon black/polyvinyl alcohol solution was placed in a micro-applicator and applied to a glass substrate by droplet deposition, as shown in FIG. 3, with a droplet diameter of about 100 μm and a center-to-center spacing of about 80 μm.
The film is placed on a heating table, and is dried and cured for 30 minutes at the temperature of 80 ℃ to obtain the carbon black/polyvinyl alcohol composite film strain sensor, the optical image of which is shown in figure 4, and the method is favorable for improving the uniformity of the film and the controllability of the size of the film.
As shown in fig. 5, the resistance-strain test was performed on the composite thin film strain sensor according to the example. It can be seen that the resistance value of the composite film increases with the increase of the strain, and the prepared film has a small thickness, so that the resistance changes obviously even under the strain change of one ten thousandth, and the composite film strain sensor of the embodiment has high sensitivity.
The substrate is a glass substrate, the length of the glass substrate is 20mm, the width of the glass substrate is 20mm, and the thickness of the glass substrate is about 300 mu m.
Specifically, in a non-contact mode, the coating device is not in contact with the substrate, only the liquid drops are in contact with the substrate to form liquid drop points, and the deposition positions of the liquid drops can be determined through software control, so that the pattern of the composite film is manufactured.
The attractive force and the surface tension among the liquid drop molecules are utilized, and the liquid drops which are partially overlapped can be mutually attracted and fused to form a whole liquid drop, so that the prepared film has better continuity and uniformity.
Because the size of the liquid drop is very small, the original minimum size of the film prepared by the liquid drop deposition method is the size of one liquid drop, so that the size of the film has higher controllability, and the waste of materials is reduced.
The main mechanism of the preparation method of the composite film strain sensor based on droplet deposition is related to intermolecular mutual attraction and surface tension. Due to the attraction between molecules, the CB/PVA droplet can be hemispherical at the needle tip and will not fall off. The surface tension between the base and the air interface is greater than the surface tension between the base and the liquid cross-section, so that when the drop approaches the upper surface of the base, part of the drop on the applicator tip is used to wet the base surface, i.e. the drop forms a plano-convex lens shape on the base surface, and the other part remains on the tip, while there is no contact between the applicator and the substrate. When the center-to-center distance between two droplets is smaller than the diameter of the droplets, there will be an overlap between the two droplets. The liquid has fluidity and the small gaps between the droplet interface molecules in the overlapped portion cause the liquid molecules inside to attract each other, and at the same time, they form a new droplet dot under the action of surface tension. The device moves along a straight line to enable the liquid drops to form a liquid drop belt, and when a plurality of liquid drop belts are overlapped, a carbon black/polyvinyl alcohol liquid drop film is formed.
The stirring at a temperature of 90 ℃ for a certain period of time is intended to dissolve the polyvinyl alcohol sufficiently.
The solution is put into a centrifugal mixer for stirring and ultrasonic treatment, and the like, which are all used for fully mixing the carbon black and the polyvinyl alcohol in the solution.
Air is mixed in the solution preparation process, the uniformity of the film is affected, and the air mixed in the solution can be removed by vacuum suction in a vacuum drying box.
The above steps were all carried out at normal pressure except for vacuum suction.
Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (1)
1. A preparation method of a composite film strain sensor based on dropping deposition is characterized by comprising the following steps:
s1: adding polyvinyl alcohol powder into distilled water to completely dissolve polyvinyl alcohol to obtain a uniform polyvinyl alcohol aqueous solution;
s2: completely mixing the carbon black solution with the polyvinyl alcohol solution to obtain a uniform carbon black/polyvinyl alcohol solution;
s3: removing air mixed in the solution to obtain pure carbon black/polyvinyl alcohol solution;
s4: putting the obtained carbon black/polyvinyl alcohol solution into a micro-coater, and coating the solution on a substrate by adopting a droplet deposition method;
s5: heating and curing the carbon black/polyvinyl alcohol film to obtain a carbon black/polyvinyl alcohol composite film strain sensor;
wherein, in the step S2, the step of completely mixing the carbon black solution and the polyvinyl alcohol solution comprises: adding the carbon black solution into the prepared polyvinyl alcohol aqueous solution, putting the mixed solution into a planetary centrifugal mixer, stirring and mixing, carrying out ultrasonic treatment in an ultrasonic cleaning machine, taking out and stirring for 10 minutes;
in the step S3, the step of removing air mixed in the solution includes: putting the carbon black/polyvinyl alcohol solution obtained in the step S2 into a vacuum drying oven for vacuum suction treatment;
in the step S1, the step of completely dissolving the polyvinyl alcohol includes: heating to 90 ℃ and stirring at this temperature for 20 minutes;
in step S4, the droplet deposition method includes: the non-contact mode is adopted, the coating device is not in contact with the substrate, only the liquid drop is in contact with the substrate to form a liquid drop point, and the deposition position of the liquid drop can be determined through software control, so that the pattern of the composite film is manufactured;
the substrate is a glass substrate.
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| US4501503A (en) * | 1979-06-04 | 1985-02-26 | Vectra International Corporation | Thermographic cholesteric coating compositions and plates |
| JPS6473245A (en) * | 1987-09-16 | 1989-03-17 | Tokai Carbon Kk | Moisture sensitive element and manufacture thereof |
| CN1113924A (en) * | 1994-06-14 | 1995-12-27 | 金博华 | Recipe for solid carbon black and producing method |
| JP5599205B2 (en) * | 2010-03-17 | 2014-10-01 | 富士フイルム株式会社 | Imprint system |
| CN104198564B (en) * | 2014-09-24 | 2016-08-17 | 云南云天化股份有限公司 | A kind of oxygen sensor protective layer and preparation method thereof |
| WO2017073796A1 (en) * | 2015-10-30 | 2017-05-04 | Sekisui Chemical Co., Ltd. | Thermoconductive material, heat sink, heat spreader, method for producing heat spreader, and method for producing thermoconductive material |
| CN105907009B (en) * | 2016-05-18 | 2018-08-24 | 郑州大学 | The preparation of conductive polymer composite and its application in strain transducer |
| CN108794911A (en) * | 2018-07-13 | 2018-11-13 | 吴江市聚盈电子材料科技有限公司 | A kind of high bending strength dielectric composite material preparation method |
| CN110078983A (en) * | 2019-05-10 | 2019-08-02 | 中国电力科学研究院有限公司 | Gloves made of latex slurry with touch screen functionality and preparation method thereof |
| CN110285898B (en) * | 2019-08-06 | 2020-04-24 | 清华大学 | Flexible pressure sensing device based on carbon black dust-free paper and manufacturing method thereof |
| CN111718584A (en) * | 2020-06-18 | 2020-09-29 | 上海交通大学 | Radiation cooling film, preparation method and application thereof |
| CN111978572A (en) * | 2020-07-21 | 2020-11-24 | 华南理工大学 | KH-560/nano ZnO composite antibacterial film with starch substrate and preparation method thereof |
| CN113337168A (en) * | 2021-05-20 | 2021-09-03 | 惠州深赛尔化工有限公司 | Acrylic resin can water-based paint and preparation method thereof |
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