阅读说明：本技术 一种微胶囊驻极体自发电装置及其制备与应用 (Microcapsule electret self-generating device and preparation and application thereof ) 是由 郑旭 周慎杰 陈玲玲 阳生有 于泽泳 于 2021-09-13 设计创作，主要内容包括：本发明属于驻极体传感器领域,涉及一种微胶囊驻极体自发电装置及其制备与应用,包括：将导电层附着在PTFE膜；将PDMS基料与固化剂混合均匀,再加入PTFE纳米颗粒和带电荷微胶囊材料,形成未固化的微胶囊/PTFE/PDMS复合材料；将未固化的微胶囊/PTFE/PDMS复合材料涂覆在PTFE膜表面,固化,得到装置上半部分；制备具有图案的模板,并在模板上涂覆脱模剂；将未固化的PDMS预聚物注入模板,固化、脱模,得到具有图案的PDMS薄膜；在PDMS薄膜表面依次负载AgNWs涂层、金属银薄膜,形成下电极；将装置上半部分、下电极、底部微结构进行组合,在导电织物与下电极之间连接导线,即得。制备的柔性微胶囊驻极体自发电装置内部外加电荷稳定且均匀、电荷储存空间封闭性更好、发电效率更高。(The invention belongs to the field of electret sensors, and relates to a microcapsule electret self-generating device and preparation and application thereof, wherein the microcapsule electret self-generating device comprises the following components: attaching a conductive layer to the PTFE membrane; uniformly mixing the PDMS base material and a curing agent, and then adding PTFE nano particles and a charged microcapsule material to form an uncured microcapsule/PTFE/PDMS composite material; coating an uncured microcapsule/PTFE/PDMS composite material on the surface of a PTFE membrane, and curing to obtain the upper half part of the device; preparing a template with a pattern, and coating a release agent on the template; injecting uncured PDMS prepolymer into a template, curing and demolding to obtain a PDMS film with a pattern; sequentially loading an AgNWs coating and a metal silver film on the surface of the PDMS film to form a lower electrode; and combining the upper half part, the lower electrode and the bottom microstructure of the device, and connecting a lead between the conductive fabric and the lower electrode to obtain the conductive fabric. The prepared flexible microcapsule electret self-generating device has the advantages of stable and uniform external charges inside, better closure of a charge storage space and higher generating efficiency.)

1. A method for preparing a microcapsule electret self-generating device is characterized by comprising the following steps:

attaching a conductive layer to the PTFE membrane;

uniformly mixing the PDMS base material and a curing agent, and then adding PTFE nano particles and a charged microcapsule material to form an uncured microcapsule/PTFE/PDMS composite material;

coating an uncured microcapsule/PTFE/PDMS composite material on the surface of a PTFE membrane, and curing to obtain the upper half part of the device;

preparing a template with a pattern, and coating a release agent on the template;

injecting uncured PDMS prepolymer into a template, curing and demolding to obtain a PDMS film with a pattern;

sequentially loading an AgNWs coating and a metal silver film on the surface of the PDMS film to form a lower electrode;

and combining the upper half part, the lower electrode and the bottom microstructure of the device, and connecting a lead between the conductive fabric and the lower electrode to obtain the micro-capsule electret self-generating device.

2. The method of making a microencapsulated electret self-generating device as claimed in claim 1 wherein the method of making the charged microcapsules comprises:

uniformly mixing the urea formaldehyde prepolymer with an emulsifier to form a water phase;

mixing SiO₂Adding the sol material toChloromethane, and mixing uniformly to form an oil phase;

adding the oil phase into the water phase, and emulsifying to form an oil-in-water emulsion;

acidifying the oil-in-water emulsion, adding resorcinol to react, collecting the product, washing, carrying out solid-liquid separation, and drying to obtain the charged microcapsule.

3. The method for preparing a microencapsulated electret self-generating device as claimed in claim 2 wherein the emulsifier is polyvinyl alcohol.

4. The preparation method of the microcapsule electret self-generating device according to claim 1 is characterized in that the preparation method of the urea formaldehyde prepolymer comprises the following steps: uniformly mixing a formaldehyde aqueous solution and urea, adding triethanolamine to adjust the pH value of a mixed system to 8-9, and heating in a water bath to react to obtain a transparent urea formaldehyde prepolymer; adding water, and cooling.

5. The method for preparing a microencapsulated electret self-generating device as defined in claim 1 wherein the conductive layer is made of a conductive fabric or a conductive film, preferably the conductive film is made of at least one of a deposited metal film, metal nanowires, conductive polymers.

6. The method of claim 1, wherein the pattern is at least one of a cone, a pyramid, and a micron-sized cylinder.

7. A microencapsulated electret self-generating device prepared by the process of any one of claims 1-6.

8. A microencapsulated electret self-generating device comprising: an upper electrode, a PTFE layer, a microcapsule/PTFE/PDMS composite layer, a lower electrode and a bottom microstructure;

the upper electrode, the PTFE layer, the microcapsule/PTFE/PDMS composite layer, the lower electrode and the bottom microstructure are sequentially arranged from top to bottom, and the upper electrode is connected with the lower electrode through a lead.

9. The electret self-generating device of claim 8, wherein the PTFE film has a thickness of 0.03 to 0.1 mm.

10. Use of the microencapsulated electret self-generating device according to any one of claims 7 to 9 in the preparation of a flexible wearable electronic device.

Technical Field

The invention belongs to the field of electret sensors, and particularly relates to a preparation method of a microcapsule electret self-generating device.

Background

The information in this background section is only for enhancement of understanding of the general background of the invention and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art that is already known to a person of ordinary skill in the art.

With the development of flexible wearable electronics, a number of emerging applications have attracted widespread attention. However, due to their portability, the energy supply of such devices has become a major problem. In recent years, energy harvesting techniques that convert energy from the environment have attracted increasing attention because they can supplement the power of small electronic products, which may enable long-term and even sustainable operation.

The electrostatic flexible electret has an additional charge built in, so that when the electret is deformed by an external load, the surface of the electrostatic flexible electret can generate the flow of the charge, and the electrostatic flexible electret has a power generation effect. The existing electret generating device is a simple composite material without patterns, has low sensitivity, generates very small electric quantity under the action of external load, is not enough to support the electric power required by a small electronic product in the use process, and limits the wide application of the electret generating device in industry.

Secondly, the electret piezoelectric sensor mainly uses the electrostatic effect of the electret, so that the electret needs to be polarized before a device is prepared, and an ultrahigh voltage charging process is carried out in the electret piezoelectric sensor. However, the charging process is likely to cause material damage, charges are likely to gather on the surface or near the surface of the material, the electret space charges are unevenly distributed, and the charges are likely to be lost along with the increase of the service time.

The schematic diagram of the existing electret is shown in fig. 1 and fig. 2:

1. the polymer is charged directly inside by high voltage, so that the polymer has additional charges inside.

2. A pattern for storing electric charges is prepared inside the polymer, and then charged by high voltage to have additional electric charges inside.

Disclosure of Invention

The invention aims to provide a preparation method of a flexible microcapsule electret self-generating device with stable and uniform internal external charges, better closure of a charge storage space and higher generating efficiency, so as to solve at least one technical problem in the background technology.

In order to achieve the technical purpose, the invention adopts the following technical scheme:

in a first aspect of the invention, there is provided a process for preparing a microencapsulated electret self-generating device, comprising:

attaching a conductive layer to the PTFE membrane;

uniformly mixing the PDMS base material and a curing agent, and then adding PTFE nano particles and a charged microcapsule material to form an uncured microcapsule/PTFE/PDMS composite material;

coating an uncured microcapsule/PTFE/PDMS composite material on the surface of a PTFE membrane, and curing to obtain the upper half part of the device;

preparing a template with a pattern, and coating a release agent on the template;

injecting uncured PDMS prepolymer into a template, curing and demolding to obtain a PDMS film with a pattern;

sequentially loading an AgNWs coating and a metal silver film on the surface of the PDMS film to form a lower electrode;

and combining the upper half part, the lower electrode and the bottom microstructure of the device, and connecting a lead between the conductive fabric and the lower electrode to obtain the micro-capsule electret self-generating device.

In contrast to the second electret of the background art, the solution of the present invention, which uses microcapsules instead of the preparation of internal charge storage spaces in the polymer, allows the formation of more stable spaces, larger spaces and more stable internal additional charges than this technique, but is not mentioned in the background section.

In a second aspect of the invention, there is provided a microencapsulated electret self-generating device prepared by any of the above-described methods.

In a third aspect of the present invention, there is provided a microcapsule electret self-generating device, including: an upper electrode, a PTFE layer, a microcapsule/PTFE/PDMS composite layer, a lower electrode and a bottom microstructure;

the upper electrode, the PTFE layer, the microcapsule/PTFE/PDMS composite layer, the lower electrode and the bottom microstructure are sequentially arranged from top to bottom, and the upper electrode is connected with the lower electrode through a lead.

In a fourth aspect of the invention, the application of the microcapsule electret self-generating device in the preparation of flexible wearable electronic equipment is provided.

The invention has the beneficial effects that:

(1) compared with the prior art, the microcapsule forming storage space has the advantages of larger storage space, better sealing property and more stable performance.

Note that: the microcapsule can form a closed space, can provide a more stable storage space for charges, and can control the charges in the microcapsule without leakage even if the internal charges are actively moved under a high temperature condition.

(2) The prepared power generation device is high in power generation efficiency.

Note that: due to the microstructure at the bottom of the electret, the contact area of the device is greatly changed under the deformation condition, so that the device has higher sensitivity and higher generating efficiency.

(3) The preparation method of the invention does not need a high-voltage charging process, is simpler and greatly reduces the preparation cost of the flexible electret.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.

FIG. 1 is a schematic view of a first electret in the prior art;

FIG. 2 is a schematic view of a second electret in the prior art;

FIG. 3 is a schematic view of an apparatus according to example 1 of the present invention, wherein 1. upper electrode, 2.PTFE, 3.PDMS, 4. microcapsule, 5.PTFE nanoparticle, 6. lower electrode, 7. bottom microstructure, and 8. conducting wire;

FIG. 4 shows charged microcapsules prepared according to example 1 of the present invention;

FIG. 5 is a schematic view of a template in example 1 of the present invention;

FIG. 6 is a diagram of a PDMS pattern in example 1 of the present invention;

fig. 7 is a test chart of the self-generating performance of the microcapsule electret self-generating device in example 1 of the present invention.

Detailed Description

It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

Interpretation of terms:

PTFE: polytetrafluoroethylene, polymer, a dielectric material.

PDMS: polydimethylsiloxane, polymer, prepolymer and curing agent the ratio of 10:1 proportion and can be solidified into flexible polymer after being heated.

Electret: electrets are a generic term for a class of dielectric materials that are capable of long-term storage of electrical charge. In the prior art, a dielectric material having a function of storing charges is generally subjected to a polarization (charging) process to store charges therein. Under the condition of external load, an electric signal is generated due to the electrostatic effect, and the effect of power generation is achieved.

A method for preparing a microcapsule electret self-generating device comprises the following steps:

attaching a conductive layer to the PTFE membrane;

uniformly mixing the PDMS base material and a curing agent, and then adding PTFE nano particles and a charged microcapsule material to form an uncured microcapsule/PTFE/PDMS composite material;

coating an uncured microcapsule/PTFE/PDMS composite material on the surface of a PTFE membrane, and curing to obtain the upper half part of the device;

preparing a template with a pattern, and coating a release agent on the template;

injecting uncured PDMS prepolymer into a template, curing and demolding to obtain a PDMS film with a pattern;

sequentially loading an AgNWs coating and a metal silver film on the surface of the PDMS film to form a lower electrode;

and combining the upper half part, the lower electrode and the bottom microstructure of the device, and connecting a lead between the conductive fabric and the lower electrode to obtain the micro-capsule electret self-generating device.

In some embodiments, the method of making the charged microcapsules comprises:

uniformly mixing the urea formaldehyde prepolymer with an emulsifier to form a water phase;

mixing SiO₂Adding the sol material into dichloromethane, and uniformly mixing to form an oil phase;

adding the oil phase into the water phase, and emulsifying to form an oil-in-water emulsion;

acidifying the oil-in-water emulsion, adding resorcinol to react, collecting the product, washing, carrying out solid-liquid separation, and drying to obtain the charged microcapsule.

In some embodiments, the emulsifier is polyvinyl alcohol.

In some embodiments, the urea formaldehyde prepolymer is prepared by the following steps: uniformly mixing a formaldehyde aqueous solution and urea, adding triethanolamine to adjust the pH value of a mixed system to 8-9, and heating in a water bath to react to obtain a transparent urea formaldehyde prepolymer; adding water, and cooling.

In some embodiments, the conductive layer is composed of a conductive fabric or a conductive film, preferably, the conductive film is made of at least one of a deposited metal film, a metal nanowire, and a conductive polymer.

In some embodiments, the pattern is at least one of a cone, a pyramid, a micron-scale cylinder.

In some embodiments, the PTFE membrane has a thickness of 0.03 to 0.1 mm.

The present invention is described in further detail below with reference to specific examples, which are intended to be illustrative of the invention and not limiting.

In the following examples, the curing agent was Dow Corning 184 silicone rubber, which was dispensed into two bottles, one bottle being the prepolymer base material and the other bottle being the curing agent. When the rubber is stored separately, the rubber is liquid with fluidity and can be solidified into a flexible solid rubber material after being mixed.

Example 1:

firstly, preparing a charged microcapsule material:

1. preparation of urea formaldehyde prepolymer of capsule shell

Adding a formaldehyde aqueous solution (37%) and urea into a beaker according to the mass ratio of 1:1, uniformly mixing, setting the rotating speed of a magnetic stirrer to 300rpm, and stirring until the formaldehyde aqueous solution and the urea are completely dissolved. Adding analytically pure triethanolamine to adjust the pH value of the mixed system to 8-9. Heating the reaction system for 60min in water bath at 70 ℃ to obtain the transparent urea formaldehyde prepolymer. Weighing the mass of the urea formaldehyde prepolymer, slowly adding room temperature deionized water with the mass 2 times that of the prepolymer, and waiting for natural cooling for later use.

2. Preparation of the aqueous phase

50ml of deionized water is heated to 50 ℃, 1.6g of PVA powder is added in multiple times at the rotating speed of 500rpm of a magnetic stirrer, then the temperature is heated to 80 ℃ and stirring is continued until the PVA powder is completely dissolved, and the PVA powder is cooled to room temperature to be used as an emulsifier for standby. 10.8g of the prepared prepolymer was added to an emulsifier and mixed well to obtain an aqueous phase.

3. Preparation of the oil phase

1g of SiO₂The sol material was added to 30g of dichloromethane as an oil phase.

4. Preparation of charged microcapsules

7.5g of the oil phase was added to 62.4g of the aqueous phase and emulsified for 5min with stirring at 800rpm to give an oil-in-water emulsion. After the emulsification is successful, the pH value of the solution is gradually adjusted to 3 by using 0.1mol/L dilute hydrochloric acid, and the acidification process is controlled to be about 2 hours. 0.5g of analytically pure resorcinol was added to the acidified solution, the temperature of the solution was raised to 60 ℃ and heated at constant temperature for 1 h. And repeatedly washing the obtained product with deionized water for 6 times, standing, removing supernatant, and drying at 60 ℃ by using a drying oven to obtain the dry charged microcapsule.

Secondly, preparing a flexible microcapsule electret self-generating device:

1. preparing the upper half part of the device:

(1) first, an upper electrode (e.g., a conductive fabric or other conductive film, such as a deposited metal film, a metal nanowire, a conductive polymer, etc., with a thickness of about 100 μm) is attached to a PTFE film (the PTFE film may have a thickness of 0.03-0.1 mm, in this embodiment, 0.1 mm).

(2) Mixing PDMS base material and curing agent according to the weight ratio of 10:1 in a mass ratio; then, the PTFE nanoparticles and the prepared charged microcapsule material were mixed in a 1: 1:1 was added to the mixture.

(3) The uncured microcapsule/PTFE/PDMS composite was spin coated onto the surface of a PTFE membrane (thickness of about 1mm) by spin coating through a spin coater.

(4) And (3) placing the composite material in an oven to be cured for 1 hour at the temperature of 80 ℃, wherein the diameter of the microcapsule after curing is 20-100 microns, and the diameter of the PTFE particles is about 200 nanometers.

2. Preparing the lower half part of the device:

(1) templates (which may be cones, pyramids, micron-sized cylinders, etc.) of acrylates were prepared by stereolithography 3D printers.

(2) A layer of low surface energy release agent (such as teflon, perfluorooctyltrichlorosilane, etc.) is spin coated on the surface of the template to assist in releasing.

(3) An uncured PDMS prepolymer (binder and curing agent ratio 10:1) was injected into the template, placed in a vacuum oven and degassed for 10 minutes to remove air bubbles, and then cured at a temperature of 80 ℃ for 1 hour. And then separating the cured PDMS film with the conical pattern on the surface from the template.

(4) A dispersion of AgNWs (silver nanowires) in alcohol was diluted to 0.5mg/mL and spin coated on a PDMS surface with a conical pattern (approximately 1mm for PDMS substrate).

(5) And depositing a layer of metal silver film (the thickness of the metal layer is about 1 micron) on the surface of the AgNWs coating by a vacuum evaporation technology to jointly form a lower electrode.

And finally combining the upper part and the lower part together to form the micro-capsule electret self-generating device.

The performance of the microencapsulated electret self-generating device prepared as described above was tested and the result is shown in fig. 7, where the device produced an alternating current of about 9 microamps maximum under compression.

It should be noted that the above-mentioned embodiments are only preferred embodiments of the present invention, and the present invention is not limited thereto, and 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 modifications and equivalents can be made in the technical solutions described in the foregoing embodiments, or equivalents thereof. 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.