CN110786845B - Preparation method of self-adjusting binding force flexible electronic system - Google Patents

Abstract

A method for preparing a self-adjusting binding force flexible electronic system is provided, which comprises the following steps: preparing a deformed flexible substrate: preparing a deformed flexible substrate to have a liquid chamber, a film-based substrate forming a chamber wall of the liquid chamber, and a combined array carried on the film-based substrate for contacting with a bonding object and applying a bonding force; filling a volatile substance into the liquid cavity, and then sealing the liquid cavity, wherein the volatile substance is in a liquid state at normal temperature; and combining a heat generating device on the deformable flexible substrate; when the heating device generates heat, the volatile substance is heated and volatilizes into a gaseous state, the film base substrate bulges towards the outside of the liquid cavity, and the combination body array deforms, so that the bonding force is reduced. The self-adjusting binding force flexible electronic system has the characteristic of autonomous regulation, and can be conveniently separated from a binding object without damaging internal electronic devices.

Description

Preparation method of self-adjusting binding force flexible electronic system

Technical Field

The invention relates to the technical field of electronic information, in particular to a method for preparing a flexible electronic system with self-adjusting binding force.

Background

Flexible electronic devices have been developed in recent years, and have made great breakthrough in structural design, manufacturing method, functional structure, and the like, and particularly in the field of health care, flexible electronic technology is playing an increasingly important role, and smart medical care, health big data, and the like are all flexible electronic devices that are integrated with human bodies. However, in these flexible electronic devices, the flexible substrate bearing the functional elements often only plays a role of bearing components, and when integrated with the target object, it still needs to be attached by other means, for example, the flexible electronic device for monitoring the body surface signals of the human body is usually attached by means of medical dressing; flexible electronic devices that are integrated with certain organs of the human body in vivo are often secured by biological suturing. These approaches either reduce the comfort of wearing or inflict additional trauma on the target, all with significant drawbacks.

Therefore, a technical problem to be solved by those skilled in the art is to enable a flexible electronic device to be flexibly, conveniently and reliably combined with and separated from a combining object without causing damage to the combining object and the flexible electronic device itself.

Disclosure of Invention

The present invention has been made in view of the state of the art described above. The present invention is directed to a method of fabricating a self-adjusting binding force flexible electronic system capable of fabricating a self-adjusting binding force flexible electronic system having a self-adjustable flexible substrate to adjust the binding of the flexible electronic system and a binding object.

The preparation method of the flexible electronic system with self-adjusting binding force comprises the following steps:

preparing a deformed flexible substrate: preparing a deformed flexible substrate to have a liquid chamber, a film-based substrate forming a chamber wall of the liquid chamber, and a combined array carried on the film-based substrate for contacting with a bonding object and applying a bonding force;

filling a volatile substance into the liquid cavity, and then sealing the liquid cavity, wherein the volatile substance is in a liquid state at normal temperature; and

combining a heating device on the deformed flexible substrate;

when the heating device generates heat, the volatile substance is heated and volatilizes into a gaseous state, the film base substrate bulges towards the outside of the liquid cavity, and the combination body array deforms, so that the bonding force is reduced.

In at least one embodiment, the deformed flexible substrate includes a bonded flexible substrate having a recess for forming the liquid chamber and a liquid chamber flexible substrate prepared using an injection molding process, the liquid chamber flexible substrate and the bonded flexible substrate being butted in a demolding direction of the injection molding process to seal the liquid chamber.

In at least one embodiment, in the step of preparing a deformed flexible substrate, the steps of:

preparing a main mold having a recessed space;

preparing a mould cover plate, wherein the mould cover plate is provided with a convex column and a liquid discharge hole;

preparing a combined body mould by adopting a photoetching mode;

assembling the main mold and the combined body mold, wherein the combined body mold is positioned in the recessed space, and the main mold and the combined body mold form a concave cavity;

pouring injection molding liquid into the concave cavity;

and assembling the mould cover plate and the main mould so that the convex column is inserted into the concave cavity, the convex column extrudes part of the injection liquid out of the liquid discharge hole, and the rest injection liquid fills the space between the mould cover plate and the main mould.

In at least one embodiment, the remaining injection molding fluid is evacuated to remove air bubbles therein.

In at least one embodiment, the master mold has a groove in a space of the recess, and the bonded body mold is mounted to the groove, supported by a bottom wall of the groove, and flush with an opening of the groove.

In at least one embodiment, the mould cover plate and the main mould have a male and female locating assembly, in which location the boss is located in the middle of the cavity.

In at least one embodiment, the step of preparing the bonded mold by photolithography includes the steps of:

preparing a substrate;

first photoetching: forming a plurality of annular etching areas on the substrate by adopting a photoetching process;

and (3) second photoetching: forming a plurality of circular etching areas in the annular etching area on the substrate by adopting a photoetching process again, wherein the outer diameter of the circular etching areas is the same as that of the annular etching areas;

the substrate thus has a plurality of recessed regions, the recessed regions having a central recessed depth smaller than the recessed depth of the peripheral recessed regions.

In at least one embodiment, in the step of preparing a deformed flexible substrate, the steps of:

preparing PDMS mixed liquid for preparing the combined flexible substrate and PDMS mixed liquid for preparing the flexible substrate of the liquid cavity, so that the proportion of curing agents in the PDMS mixed liquid for preparing the combined flexible substrate is smaller than that of the curing agents in the PDMS mixed liquid for preparing the flexible substrate of the liquid cavity;

bonding the chamber flexible substrate and the bonded flexible substrate to seal the chamber.

In at least one embodiment, the heat generating device includes a heat generating circuit, the heat generating circuit is prepared using a photolithography process, and then the heat generating circuit is combined with the deformed flexible substrate using a transfer process.

In at least one embodiment, the flexible electronic system includes a functional device including functional circuitry, the functional circuitry being fabricated using a photolithographic process, after bonding the heat generating circuitry to the deformed flexible substrate:

and pouring injection molding liquid on the heating circuit, combining the functional circuit with the injection molding liquid, pouring injection molding liquid on the functional circuit, and after the injection molding liquid is solidified, integrating the functional circuit and the heating circuit into a whole and packaging the integrated circuit.

The technical scheme provided by the disclosure at least has the following beneficial effects:

the flexible electronic system with the self-adjusting binding force adjusts the effective binding area between the deformed flexible substrate and the binding object through gas-liquid two-phase conversion, thereby realizing the autonomous regulation and control of the interface binding force, flexibly realizing the close attachment with the binding object or the separation from the binding object, having the characteristic of repeated cycle use for many times, and simultaneously having the characteristic of autonomous regulation and control, being capable of conveniently separating from the binding object without damaging the internal electronic device.

The volatile substance not only has the function of adjusting the internal pressure, but also has a certain strain isolation function. The deformed flexible substrate is equivalent to providing a "floating island" structure, i.e., the deformed film-based substrate floats in a liquid, and a large amount of deformation is offset by the flow of the liquid and is not transferred to the deformed flexible substrate on the other side. Therefore, the self-adjusting binding force flexible electronic system is not only suitable for small-deformation scenes, but also suitable for large-deformation scenes.

The technical scheme can also have the following effects:

the liquid cavity flexible substrate and the combined flexible substrate are prepared by adopting PDMS mixed liquid with different proportions, so that the bending rigidity of the liquid cavity flexible substrate is greater than that of the combined flexible substrate, and when the internal pressure of the liquid cavity is increased, induced deformation only occurs on one side of the combined array, and the deformation of the liquid cavity flexible substrate is reduced or avoided as much as possible.

Drawings

Fig. 1a shows a state before deformation of a self-adjusting binding force flexible electronic system prepared by a preparation method provided by the present disclosure.

Fig. 1b shows a deformed state of the self-adjusting binding force flexible electronic system prepared by the preparation method provided by the present disclosure.

FIG. 1c is an exploded view of one embodiment of a self-adjusting binding force flexible electronic system made using the fabrication methods provided by the present disclosure.

Fig. 2a is a perspective view of a bonded flexible substrate of a self-adjusting bonding force flexible electronic system prepared using a preparation method provided by the present disclosure.

Fig. 2b is a longitudinal sectional view of the bonded flexible substrate of fig. 2 a.

Fig. 3 is a schematic diagram of the flexible malleable heating resistance of the self-adjusting binding force flexible electronic system of fig. 1a and 1 b.

Fig. 4 is a schematic view of a flexible malleable battery of the self-adjusting binding force flexible electronic system of fig. 1a and 1 b.

Fig. 5 is a schematic view of the functional device of the self-adjusting binding force flexible electronic system of fig. 1a and 1 b.

Fig. 6a is a perspective view of a first photoresist mask used in the fabrication method provided by the present disclosure.

Fig. 6b is a longitudinal cross-sectional view of the first photoresist mask of fig. 6 a.

Fig. 7 is a perspective view of a second photoresist mask used in the fabrication method provided by the present disclosure.

Fig. 8a is a perspective view of a conjugant mold used in the preparation method provided by the present disclosure.

Fig. 8b is a longitudinal sectional view of the coupled body mold in fig. 8 a.

Fig. 9 is a perspective view of a main mold employed in the manufacturing method provided by the present disclosure.

Fig. 10 is a perspective view of a mold cover plate used in the manufacturing method provided by the present disclosure.

FIG. 11 shows a schematic of filling a bonding flexible substrate with a volatile substance using the fabrication method provided by the present disclosure.

Fig. 12 is a block flow diagram of a preparation method provided by the present disclosure.

Description of reference numerals:

11 a combined flexible substrate, 111 a film substrate, 112a combined body array, 112a micro-column, 112b micro-sucker, 12a liquid cavity flexible substrate, 13 an interval flexible substrate, 14 an encapsulation flexible substrate;

2, a liquid cavity;

3 a volatile substance;

4 heating devices, 41 flexible extensible battery packs, 411 thin-film battery units, 412 connecting leads, 413 electric control switches, 42 flexible extensible heating resistors, 421 resistance wires and 422 electrodes;

6 functional devices, 61, 62, 63 flexible malleable wires, 641 temperature sensor, 642 stress strain sensor, 643 photo oximeter sensor, 644 ultraviolet light sensor, 65 wireless transmission module, 66 battery module, 67 antenna;

71 main die, 711 groove, 712 recessed space, 713 alignment clamp column, 72 combination die, 721 recessed area, 73 die cover plate, 731 plate body, 732 convex column, 733 drain hole, 734 alignment clamp groove;

81 a first photoresist mask, 810 a first photoresist layer, 811 an annular hollowed-out area, 82 a second photoresist mask, 821 a circular hollowed-out area;

9 syringe.

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.

The present disclosure provides a method for preparing a self-adjusting binding force flexible electronic system as shown in fig. 1a to 1c, which can be bound to a living body such as a human body, an animal body, etc. to measure a vital parameter of the living body. An embodiment of the self-adjusting binding force flexible electronic system will be described below with reference to fig. 1a to 2b, for example, in conjunction with a human body.

As shown in fig. 1c, the self-adjusting binding force flexible electronic system of the present invention mainly comprises: the flexible substrate, the volatile substance 3, the heat generating device 4, the spacing flexible substrate 13, the functional device 6 and the packaging flexible substrate 14. The flexible substrate may include a bonding flexible substrate 11 and a liquid chamber flexible substrate 12, and the bonding flexible substrate 11, the liquid chamber flexible substrate 12, the heat generating device 4, the spacing flexible substrate 13, the functional device 6, and the encapsulation flexible substrate 14 are sequentially stacked to form a stacked structure.

The deformable flexible substrate has a liquid chamber 2, the liquid chamber 2 being adapted to contain a volatile substance 3. The heat generating device 4 is used to realize a heat generating function so that the volatile substance 3 receives heat, and the heat generating device 4 includes, for example, a flexible stretchable heat generating resistor 42 and a flexible stretchable battery pack 41. The functional device 6 is used for realizing the data acquisition and transmission functions of the self-adjusting binding force flexible electronic system. The spacing flexible substrate 13 is positioned between the heat generating device 4 and the functional device 6 to prevent the heat generating device 4 and the functional device 6 from contacting, thereby ensuring that the functional device 6 is insulated from the heat generating device 4 and preventing the circuit of the functional device 6 from generating heat to interfere with the phase change of the volatile substance 3. The encapsulating flexible substrate 14 and the spacer flexible substrate 13 are located on opposite sides of the functional device 6.

The deformed flexible substrate has a recess portion forming the liquid chamber 2, and the flexible substrate 11 and the liquid chamber flexible substrate 12 are joined in a predetermined direction, which is a mold release direction when the recess portion is formed by performing an injection molding process, so that the deformed flexible substrate can be easily manufactured by the injection molding process, thereby forming the liquid chamber 2.

The bonding flexible substrate 11 and the liquid chamber flexible substrate 12 may be butted, for example, in the stacking direction, and the liquid chamber flexible substrate 12 may carry the heat generating device 4.

The combined flexible substrate 11 may include a bottom wall and a side wall, the combined array 112 is combined with the bottom wall, the side wall and the bottom wall enclose a concave portion, and the liquid chamber flexible substrate 12 may be formed into a sheet body, so that the liquid chamber 2 can contain more volatile substances 3. Alternatively, in other embodiments, the depression may also be formed entirely in the liquid chamber flexible substrate 12, or the depression may be formed in both the liquid chamber flexible substrate 12 and the bonding flexible substrate 11.

In other embodiments, the deformed flexible substrate may be formed by other processes, for example, the deformed flexible substrate is printed by 3D printing, and small holes are reserved only on the sides of the deformed flexible substrate in the stacking direction to pour the volatile substance 3.

As shown in fig. 2a and 2b, the bonding flexible substrate 11 has a function of adjusting the bonding capability of the flexible electronic system, and is directly in contact with the bonding object. The bonded flexible base 11 may include a bonded body array 112 and a film-based substrate 111 carrying the bonded body array 112, the film-based substrate 111 being a planar body at normal temperature, the film-based substrate 111 being formed as a bottom wall of the above-mentioned bonded flexible base 11, the bonded body array 112 for contacting and applying a bonding force to a bonding object, the bonded body array 112 including a plurality of bonded bodies, the plurality of bonded bodies being uniformly distributed around a center of the film-based substrate 111.

The bonding flexible substrate 11 is preferably an integrally formed piece. The flexible substrate 12 of the liquid chamber may be bonded to the bonded flexible substrate 11 by means of, for example, gluing.

The combined array 112 may include a microcolumn array imitating gecko's foot setae and a micro-suction cup array imitating an octopus tentacle, the microcolumn array including a plurality of micro-columns 112a, the micro-suction cup array including a plurality of micro-suction cups 112b, the number of the micro-columns 112a and the micro-suction cups 112b being the same. The base ends of the micro-pillars 112a are connected to the film base substrate 111, and the tip of each micro-pillar 112a is provided with a micro-suction pad 112 b.

The plurality of combinations of the combination array 112 may be arranged in a circle, a square, or the like. The micro-suction cups 112b may have a hemispherical space (as shown in fig. 2b), for example, but in other embodiments, the micro-suction cups 112b may have a columnar space (as shown in fig. 8b), a horn-shaped space, or the like. The diameter of the micro pillars 112a and the diameter of the micro pads 112b may be 100 to 300 micrometers, and the height of the micro pillars 112a may be 1 to 5 times the diameter thereof.

The film-based substrate 111 forms the walls of the liquid chamber 2 and has good deformability, which easily deforms under pressure, and when the film-based substrate 111 deforms, the array of bonded bodies 112 deforms, with a portion of the bonded bodies or the entire bonded bodies turning and no longer providing a bonding force.

The volatile substance 3 is a substance that is volatile by heat and has a low boiling point, such as ethanol, acetone, or the like, and the volatile substance 3 is liquid at normal temperature and easily volatilizes to a gaseous state when heated, so that the internal pressure of the liquid chamber 2 increases, and the film base substrate 111 swells. The volatile substance 3 returns to a liquid state at normal temperature to reduce the internal pressure of the liquid chamber 2, while the film base substrate 111 is restored. Thus, the volatile substance 3 functions to regulate the internal pressure of the liquid chamber 2.

It is preferable that the bending rigidity of the other portion (for example, the liquid chamber flexible base 12) of the deformed flexible substrate than the film base substrate 111 and the bonded body array 112 is made larger than the bending rigidity of the film base substrate 111. Flexural rigidity

(E is the modulus of elasticity of the material and h is the thickness of the corresponding member) is related to the modulus of elasticity E of the material and the thickness h of the corresponding member.

For example, the flexible liquid chamber base 12 may be a planar body, and the flexible liquid chamber base 12 and the film base substrate 111 may be made of the same flexible material, while the bending rigidity of the flexible liquid chamber base 12 is made larger than that of the film base substrate 111 by making the thickness of the flexible liquid chamber base 12 larger than that of the film base substrate 111. The use of the same materials for the flexible base 12 and the film-based substrate 111 facilitates the fabrication of the self-aligning bonded flexible electronic system.

Alternatively, the flexible liquid chamber base 12 and the film base 111 may be made of two different materials, and the respective thicknesses may be adjusted according to the above formula so that the bending rigidity of the flexible liquid chamber base 12 is greater than that of the film base 111. The bending rigidity of the spacer flexible substrate 13 and the encapsulating flexible substrate 14 is not particularly limited.

The bending stiffness of the flexible base 12 of the liquid chamber is greater than that of the film-based substrate 111, so that when the internal pressure of the liquid chamber 2 is increased, the induced deformation only occurs or mainly occurs in the film-based substrate 111, and the deformation of the flexible base 12 of the liquid chamber is reduced or avoided as much as possible, thereby avoiding the deformation from affecting the heating device 4.

As shown in fig. 1a, when the flexible electronic system with self-adjusting bonding force is to be bonded to a bonding object, the volatile substance 3 inside the bonding flexible substrate 11 is in a liquid state, the film-based substrate 111 is kept in a plane, the micro-cylinders 112a of the micro-cylinder array are parallel to each other, and the orientation of the micro-suction cups 112b is consistent, so that the gas inside the micro-suction cups 112b can be exhausted by applying uniform pressure toward the bonding object, for example, so that the inside of the micro-suction cups 112b has negative pressure and achieves the bonding purpose.

As shown in fig. 1b, when the flexible electronic system with self-adjusting binding force needs to be separated from the binding surface of the binding object, the volatile substance 3 in the liquid chamber 2 is volatilized, so that the internal pressure of the liquid chamber 2 increases, the film substrate 111 swells and deforms and drives the micro-cylinder array on the surface of the film substrate to deform, that is, a part of the micro-cylinders 112a makes a certain rotation around the base end, and the rotation of the micro-cylinders 112a drives the orientation of the corresponding micro-suction cups 112b to change. Thus, the bonding area of the self-adjusting bonding force flexible electronic system and the bonding object is reduced, the bonding force therebetween is weakened, and the self-adjusting bonding force flexible electronic system can be detached from the bonding object.

The self-adjusting binding force flexible electronic system adjusts the effective binding area between the binding flexible substrate 11 and the binding object through gas-liquid two-phase conversion, thereby realizing the autonomous regulation and control of the interface binding property, flexibly realizing the close attachment with the binding object or the separation from the binding object, having the characteristic of repeated cycle use, and simultaneously having the characteristic of autonomous regulation and control, being capable of conveniently separating from the binding object without damaging the internal electronic device.

The volatile substance 3 not only has the function of adjusting the internal pressure, but also has a certain strain isolation function. The deformed flexible substrate (combined with the flexible substrate 11) is equivalent to providing a "floating island" structure, i.e., the deformed film-based substrate 111 floats in the liquid, and a large amount of deformation is offset by the flow of the liquid and is not transmitted to the deformed flexible substrate (liquid chamber flexible substrate 12) on the other side. Therefore, the self-adjusting binding force flexible electronic system is not only suitable for small-deformation scenes, but also suitable for large-deformation scenes.

In the present embodiment, the bonded body array 112 forms the bonding force bionically, but in other embodiments, a conventional bonded body array forming the bonding force by an intermolecular force may be used.

As shown in fig. 3, the flexible malleable heating resistor 42 includes a resistive wire 421 and an electrode 422. The resistance value of the resistance wire 421 is R ═ ρ l/S (where ρ is the resistivity of the metal material from which the resistance wire 421 is made, l is the length of the resistance wire 421, and S is the cross-sectional area of the resistance wire 421), and the length or cross-sectional area of the resistance wire 421 can be adjusted according to the actual use situation.

The resistance wire 421 may extend, for example, along a curved path, the resistance wire 421 substantially filling the liquid chamber 2, as seen in the stacking direction, so that heat can be quickly and efficiently transferred to the volatile substance 3. The resistance wire 421 has a meandering pattern, e.g., a serpentine shape, i.e., the resistance wire 421 extends along a serpentine path and/or the resistance wire 421 may be repeatedly folded back on both sides of the extending path while extending to form, e.g., a serpentine shape. This ensures that the resistance wire 421 is not damaged by deformation due to force when the flexible electronic system is deformed, and the flexible extensible heating resistor 42 can work normally when the flexible electronic system is under tension.

The self-adjusting bonding force flexible electronic system adjusts the volatile substance 3 to perform gas-liquid two-phase conversion through the flexible extensible heating resistor 42, so that the membrane base substrate 111 is adjusted to be switched between the bulging deformation state and the initial state, the strength of the bonding capability is actively adjusted, and compared with a traditional flexible electronic device, the self-adjusting bonding force flexible electronic system is more convenient to combine with and separate from a combined object, and the combined object feels more comfortable when the combined object is separated.

The self-adjusting bonding force flexible electronic system controls the volatilization amount of the volatile substance 3 by controlling the heating time and the heating temperature of the flexible extensible heating resistor 42, thereby controlling the internal pressure of the liquid chamber 2, and adjusting the deformation amount of the film substrate 111 and the corner of the micro-suction cup 112b, thereby continuously adjusting the interface bonding strength.

As shown in fig. 4, the flexible malleable battery pack 41 includes a plurality of thin film battery cells 411 connected in series, an electronically controlled switch 413, and malleable connection wires 412 connecting the thin film battery cells 411 and the electronically controlled switch 413. The electronic control switch 413 is wirelessly controlled by an external controller to switch on or off the circuit, so as to control the flexible stretchable heating resistor 42 to generate heat or not to generate heat. The two thin-film battery cells 411 of the flexible stretchable battery pack 41 are connected with the two electrodes 422 of the flexible stretchable heating resistor 42 to supply electric energy to the flexible stretchable heating resistor 42, so that the flexible stretchable heating resistor 42 can generate heat when electrified. The flexible and extensible battery pack 41 adopts a structure of combining a plurality of thin-film battery units 411, and can ensure certain battery capacity so that the flexible and extensible heating resistor 42 can be used for multiple times. Since the thin film battery cell 411 itself has a light and thin characteristic, the thin film battery cell 411 does not affect the flexibility of the flexible electronic system with self-adjusting binding force. The connecting wires 412 can be repeatedly folded back on two sides of the extending route to form a general serpentine shape during the extending process, so that the flexible and extensible battery pack 41 has both flexible and extensible characteristics.

The plurality of thin-film battery cells 411 of the flexible malleable battery pack 41 may be arranged along a circular path, so that the resistance wire 421 of the flexible malleable heating resistance 42 may be arranged radially inside the flexible malleable battery pack 41.

As shown in fig. 5, the functional device 6 may include a battery module 66, a temperature sensor 641, a stress strain sensor 642, a photo-oximetry sensor 643, an ultraviolet light sensor 644, a wireless transmission module 65, and an antenna 67. The battery module 66 is mainly used for supplying power, each sensor is mainly used for monitoring human body related physical sign parameters, and the battery module 66 is connected with the wireless transmission module 65 through the flexible extensible lead 62 and is also connected with the sensor through the flexible extensible lead, so that electric energy is supplied to the sensor and the wireless transmission module 65. The sensor is connected to the wireless transmission module 65 by a flexible malleable wire 61, so as to transmit the acquired signal to the wireless transmission module 65. The wireless transmission module is connected with an antenna 67 through a flexible extensible wire 63 and transmits the acquired signals to the mobile terminal. The wireless transmission module 65 may be a bluetooth module, an NFC module, a module for transmitting information using ultrasound, or the like. The antenna 67 may be circular, for example, and may be arranged to correspond to the edge or the outside of the liquid chamber 2 to ensure that it is deformed less by force and that information transmission is continued stably.

It should be understood that not all of the wires are shown in fig. 5, but only the flexible malleable wires 61, 62, 63 between the sensor and the wireless transmission module 65, between the battery module 66 and the wireless transmission module 65, and between the wireless transmission module 65 and the antenna 67 are schematically shown.

The self-adjusting binding force flexible electronic system adopts various sensors, realizes synchronous detection of various information, and realizes real-time interaction with a mobile terminal and the like by adopting a wireless transmission mode.

The flexible electronic system realizes self-adjusting binding force through reasonable layout of devices (the antenna 67, the flexible extensible heating resistor 42 and the like), flexible extensible mechanical design and design of a combination array on the surface of the flexible substrate.

When it is required to couple the flexible electronic system with self-adjusting coupling force to the coupled object, the temperature sensor 641, the stress strain sensor 642, the photo blood oxygen sensor 643 and the ultraviolet light sensor 644 respectively measure the temperature, stress, blood oxygen and the amount of ultraviolet light irradiation received at the coupling portion with the human body. The information collected by these sensors is transmitted to the wireless transmission module 65 through the flexible extensible wires 61, the wireless transmission module 65 is connected with the antenna 67 through the flexible extensible wires 63, and the battery module 66 supplies electric energy to other devices of the functional device 6. The information collected by these sensors is transmitted by wireless transmission to a wireless terminal (e.g., a mobile phone) for processing and analysis.

When the self-adjusting binding force flexible electronic system needs to be separated from the binding object, the flexible extensible battery pack 41 provides electric energy for the flexible extensible heating resistor 42, the flexible extensible heating resistor 42 starts to generate heat, so that the volatile substance 3 in the liquid cavity 2 volatilizes, the internal pressure of the liquid cavity 2 is increased, the film substrate 111 swells, at least part of the micro suction cups 112b are separated from the binding object, and the self-separation of the self-adjusting binding force flexible electronic system is realized.

When the flexible extensible heating resistor 42 is no longer powered, the temperature in the liquid chamber 2 gradually decreases, the swollen film-based substrate 111 gradually returns to the initial state, and after the film-based substrate 111 completely returns to the initial state, the self-adjusting bonding force flexible electronic system can be bonded for the second time, so that the self-adjusting bonding force flexible electronic system has the advantage of being reusable.

In the present embodiment, both the film-based substrate 111 and the liquid chamber flexible base 12 are circular, and in other embodiments, the film-based substrate 111 and the liquid chamber flexible base 12 may have other shapes, such as a square shape, and the liquid chamber 2 may have, for example, a truncated cone shape, in addition to a cylindrical shape.

The flexible substrate (combined with the flexible substrate 11, the flexible substrate 12 of the liquid chamber, the spacing flexible substrate 13 and the flexible substrate 14 of the package) can be made of a silicone material such as Polydimethylsiloxane (PDMS) and copolyester (Ecoflex).

In other embodiments, the flexible electronic system may also have other kinds and numbers of sensors, such as humidity sensors, pressure sensors, etc.

The following describes a method for fabricating the self-adjusting bonding force flexible electronic system.

The above-described bonded flexible substrate 11 is prepared by an injection molding process.

First, the main mold 71, the combined body mold 72, and the mold cover 73, which are applied during the injection molding process, are prepared.

A. As shown in fig. 6a to 8b, the preparation of the bonded body mold 72 having a size complementary to that of the micro-suction cups 112b and the micro-pillars 112a according to the structure of the bonded body, particularly, according to the structure of the micro-suction cups 112b and the micro-pillars 112a, comprises the steps of:

A-S1 to A-S5, first lithography:

A-S1, preparing a substrate (e.g., a silicon wafer). Cleaving the silicon wafer into a specific shape according to the size of the bonded body array 112 to serve as a substrate of the bonded body mold 72, removing photoresist possibly remaining on the surface of the silicon wafer with acetone, and then cleaning the acetone with ethanol;

a-S2, spin coating first photoresist layer 810: spin-coating negative photoresist (e.g., ENPI202) on the cleaved silicon wafer at low speed (e.g., 600 r/min) and high speed (e.g., 3000 r/min), respectively, and baking at 110 deg.C for 5min to cure the photoresist;

A-S3, ultraviolet exposure: attaching a first mask plate on the first photoresist layer 810, then performing ultraviolet exposure for 14s, for example, on the first photoresist layer 810 to which the first mask plate is attached, and baking for 5min at 110 ℃ for example after the exposure to perform hardening;

A-S4, first development: developing, for example, 35S on the first photoresist layer 810 hardened in the steps a-S3 to form a patterned first photoresist mask 81 as shown in fig. 6a and 6b, wherein the first photoresist mask 81 has a plurality of annular hollow-out regions 811, and the annular hollow-out regions 811 correspond to annular etching regions required for etching;

A-S5, first mold etch. The substrate with the first photoresist mask 81 is subjected to inductively coupled plasma etching to a specific depth (e.g., 5 μm), and then the residual photoresist on the surface of the substrate is removed using acetone, and then the acetone is cleaned with ethanol and then dried.

A-S6, second photoetching. As shown in fig. 7, a second photoresist mask 82 is formed by photolithography using steps similar to a-S1 to a-S5, where the second photoresist mask 82 has a plurality of circular hollow-out regions 821, and the circular hollow-out regions 821 correspond to circular etching regions required for etching, and then etched to a specific depth (for example, 20 μm) by using an inductively coupled plasma, and then the residual photoresist on the surface of the substrate is removed by using acetone, and then the acetone is cleaned by using ethanol, and then dried.

a-S7, the bonded body mold 72 prepared according to the above steps is subjected to a mold release treatment. The bonded mold 72 formed in steps a to S6 is placed in a release agent (e.g., a trimethylchlorosilane solution, the volume ratio of trimethylchlorosilane to isooctane being approximately 1: 500) and soaked, for example, for 30to 60 minutes, thereby completing the release treatment of the bonded mold 72.

The outer diameter of the circular etched region formed in the second photolithography step is the same as the outer diameter of the annular etched region formed in the first photolithography step. After two etching processes, the substrate has a plurality of recessed regions 721, and the recessed depth of the center of the recessed regions 721 is smaller than that of the edge (as shown in fig. 8a and 8 b). The bonded body mold 72 has a plate shape, and the plate surface of the bonded body mold 72 has the plurality of recessed regions 721.

B. Preparing the main mold 71 and the mold cover plate 73 includes the steps of:

B-S1, preparing the main die 71.

As shown in fig. 9, the main mold 71 is made of teflon mainly by using 3D printing technology or machining for easy demolding.

The main mold 71 has a concave space 712, and the bottom wall of the concave space 712 may have a groove 711. Master mold 71 may also have alignment posts 713, and alignment posts 713 are located at the edge of master mold 71 and are used to cooperate with alignment slots 734 (described below) on mold cover 73 to form a male-female alignment assembly, thereby ensuring that master mold 71 is in relative position with mold cover 73 and that posts 732 are located in the middle of recessed space 712 (and the later-described cavity) to form bonded flexible substrate 11 with a uniform wall thickness.

B-S2, preparing a mold cover plate 73.

As shown in fig. 10, a 3D printing technique or a machining method is adopted, and a mold cover plate 73 is made of polytetrafluoroethylene as a main material to facilitate demolding.

The mold cover 73 has a plate 731, a boss 732 extending from the center of the plate 731, and a drain hole 733 provided at the edge of the plate 731. The mold cover 73 can be mounted with the main mold 71 and the posts 732 inserted into the recessed spaces 712. The mold cover plate 73 may further have alignment notches 734, and the alignment notches 734 are disposed on the plate body 731 and are configured to cooperate with the alignment pins 713 of the main mold 71 to form a male-female positioning assembly. Alignment key post 713 and alignment key slot 734 are aligned in the demolding direction.

The dimensions of the bonded flexible substrate 11 (e.g., wall thickness, size of the fluid chamber 2, etc.) may be adjusted by changing the relative dimensions of the main mold 71 and the mold cover 73.

In other embodiments, the master mold 71 may have alignment bayonet slots 734 and the mold cover plate 73 may have alignment bayonet posts 713.

C. Pouring to form a combined flexible matrix, comprising the following steps:

C-S1, assembling the combined body mold 72 and the master mold 71. The combined body mold 72 is mounted to the groove 711 of the main mold 71 so as to be supported by the bottom wall of the groove 711, and the combined body mold 72 is flush with the opening of the groove 711 in the depth direction of the groove 711 so that the main mold 71 and the combined body mold 72 form a cavity with a flat bottom wall, and the depression 721 of the combined body mold 72 is open to the above-mentioned cavity of the main mold 71. Thus, when the injection liquid is poured into the main mold 71, the integrated bonded body array 112 and the film base substrate 111 can be formed, and the bonded body mold 72 is not extruded.

C-S2 and pouring injection molding liquid. In order to ensure that the side of the flexible substrate 11 on which the array of connected bodies 12 is bonded is easily deformed when being subjected to the pressure of the liquid chamber 2, the injection molding liquid is a PDMS (polydimethylsiloxane) mixed liquid with a volume ratio of the body to the curing agent of 20:1, and after the PDMS mixed liquid is mixed, the PDMS mixed liquid is injected into the cavity formed by the main mold 71 and the connected body mold 72.

C-S3, assembling the mold cover plate 73. The alignment clamp 734 of the mold cover plate 73 is aligned with the alignment clamp 713 of the main mold 71, the convex column 732 extrudes part of the injection liquid from the liquid discharge hole 733, the space occupied by the convex column 732 forms the liquid cavity 2, and the rest of the injection liquid fills the space between the mold cover plate 73 and the main mold 71 to form the bonded flexible substrate 11.

C-S4, and curing. After steps C-S3, the injection molding fluid is evacuated to remove air bubbles therein and cured at room temperature, for example, for 3 days, or at, for example, 65℃, for example, for 4 hours, at a suitable temperature to ensure that the bonded flexible substrate 11 is not susceptible to breaking during deformation.

D. As shown in fig. 11, a volatile substance, such as ethanol or acetone, is injected into the liquid chamber 2 bonded to the flexible substrate 11 using, for example, a syringe 9.

E. The heat generating device 4 is prepared and bonded to the bonding flexible substrate 11. The heating device 4 comprises a heating circuit, the heating circuit comprises an electrode 422 and a resistance wire 421, and the step E specifically comprises the following steps:

E-S1, preparing a flexible substrate film on a hard base. PMMA (polymethyl methacrylate, which is a positive photoresist that can be used as a sacrificial layer) and PI (polyimide, which can be used as a flexible substrate film) are spin-coated on, for example, a silicon wafer or a glass plate, respectively, and baked. In the case of spin-coating PMMA, spin-coating is carried out at a low speed (e.g., 600 r/min) and a high speed (e.g., 3000 r/min), respectively, and then baked at, for example, 180 ℃ for, for example, 20min to be cured into a film. Then spin-coating PI, respectively spin-coating at low speed (such as 800 r/min) and high speed (such as 3000 r/min), and heating in a step heating manner to cure the PI, such as heating at 80 deg.C for 30min, 120 deg.C for 30min, 150 deg.C for 30min, 180 deg.C for 30min, and 190 deg.C for 60min, to form a PI flexible substrate film.

E-S2, and depositing a metal film. Depositing a copper film with the thickness of about 400nm on a hard substrate with a PI flexible substrate film by adopting an electron beam evaporation coating mode.

And E-S3, preparing a circuit by adopting a photoetching process. For example, a positive photoresist (e.g., AZ5214) is spin-coated on a hard substrate on which a copper thin film is deposited at a low speed (e.g., 600 r/min) and a high speed (e.g., 3000 r/min), respectively, and baked at, for example, 110 ℃ for, for example, 90 seconds to cure and bake. A patterned photoresist mask is then formed by uv exposure for, for example, 14s and removal of excess photoresist with a developer solution. The copper film is then patterned using a copper etchant to form the same pattern as the photoresist mask, forming copper electrodes and copper resistors. The etching time of the copper etching solution is related to the concentration of the etching solution.

E-S4, transfer printing. The prepared copper electrode and copper resistor are transferred from the hard substrate to a flexible substrate by means of transfer printing, and the flexible substrate can be used as the liquid cavity flexible substrate 12. The flexible substrate is prepared by pouring PDMS mixed liquid with the volume ratio of the body to the curing agent being 10:1, so that the elastic modulus of the flexible substrate is higher than that of the combined flexible substrate 11, and further the deformation of the flexible electronic system under the condition of increased internal pressure has certain directionality. The PI flexible substrate film is patterned into a pattern conforming to the copper electrode using a reactive ion etching (RIE for short) process at a power of, for example, 100w and an oxygen partial pressure of 30 torr.

E-S5, and welding the functional units. Electrode solder (e.g., solder paste) is printed by screen printing. After the solder is printed, the functional units (e.g., the thin film battery cell 411 and the electrical control switch 413) are placed in corresponding positions to make electrical connection with the copper resistors.

F. A functional device 6 is prepared, the functional device 6 including a functional circuit and a device, and step F the functional circuit is prepared in a similar manner to step E, except that in step F, each sensor is electrically connected to the functional circuit.

G. A packaged circuit comprising the steps of:

G-S1, after the step F, pouring PDMS mixed liquid (the volume ratio of the body to the curing agent is 10:1) on the heating circuit, then laminating the functional circuit on the PDMS mixed liquid, after the PDMS mixed liquid poured in the middle is cured, bonding the functional circuit and the driving circuit into a whole, and forming the flexible substrate 13 by the PDMS mixed liquid in the middle.

G-S2, pouring the PDMS mixed solution (the volume ratio of the body to the curing agent is 10:1) into a cylindrical mold for example so as to form the packaging flexible substrate 14 on the functional device 6, and packaging the flexible substrate 14 to package the circuit.

H. And (4) system integration. The encapsulated circuit is bonded to the bonded flexible substrate 11 which has been impregnated with the volatile substance 3 using, for example, a silicone adhesive.

It should be understood that in the above description, for clarity of explanation, only one specific material is used as an example for each of the various materials involved. For example, negative photoresist ENPI202 is used as a photoresist for preparing the bonding body mold 72, PDMS mixed liquid is used for pouring and bonding the flexible substrate and the flexible substrate, ethanol is used as the volatile substance 3, a silicon wafer is used as a substrate for preparing the bonding body mold 72, polytetrafluoroethylene materials are used for preparing the main mold 71 and the mold cover plate 73, a copper film is used for preparing a heating circuit, and solder paste is used as an electrode adhesive for welding. In other embodiments, other materials commonly found in the art may be substituted for the above materials.

It should also be understood that the above-referenced process parameters of temperature, time, rotational speed, etc. are merely exemplary and may be adjusted in other embodiments.

The various steps referred to above may be interchanged in order to meet the requirements of the inventive concept. For example, step a and step B may be performed simultaneously or sequentially, step E and step F may be performed simultaneously or sequentially, and step D and step G may be performed simultaneously or sequentially.

It should be understood that the above embodiments are only exemplary and are not intended to limit the present invention. Various modifications and alterations of the above-described embodiments may be made by those skilled in the art in light of the teachings of the present invention without departing from the scope thereof.

Claims (10)

1. A preparation method of a flexible electronic system with self-adjusting binding force is characterized by comprising the following steps:

preparing a deformed flexible substrate: preparing a deformed flexible substrate to have a liquid chamber (2), a film-based substrate (111) and a bonded array (112) carried on the film-based substrate (111), the film-based substrate (111) forming a chamber wall of the liquid chamber (2), the bonded array (112) being for contacting a bonding object and applying a bonding force;

filling a volatile substance (3) into the liquid cavity (2), and then sealing the liquid cavity (2), wherein the volatile substance (3) is in a liquid state at normal temperature; and

combining a heating device (4) on the deformed flexible substrate;

when the heat generating device (4) generates heat, the volatile substance (3) is heated and volatilizes into a gaseous state, the film substrate (111) bulges towards the outside of the liquid cavity (2), and the combination body array (112) deforms, so that the bonding force is reduced.

2. The method for manufacturing a self-adjusting bonding force flexible electronic system according to claim 1, wherein the deformed flexible substrate comprises a bonded flexible substrate (11) and a liquid chamber flexible substrate (12), the bonded flexible substrate (11) has a recess for forming the liquid chamber (2), the bonded flexible substrate (11) is manufactured by an injection molding process, and the liquid chamber flexible substrate (12) is butted with the bonded flexible substrate (11) along a demolding direction of the injection molding process so as to seal the liquid chamber (2).

3. The method for preparing a self-adjusting bonding force flexible electronic system according to claim 2, wherein the step of preparing a deformed flexible substrate comprises the steps of:

preparing a main mold (71), wherein the main mold (71) is provided with a concave space (712);

preparing a mold cover plate (73), wherein the mold cover plate (73) is provided with a convex column (732) and a liquid discharge hole (733);

preparing a combined body mould (72) by adopting a photoetching mode;

assembling the main mold (71) and the bonded body mold (72), the bonded body mold (72) being located in the recessed space (712), the main mold (71) forming a cavity with the bonded body mold (72);

pouring injection molding liquid into the concave cavity;

the mold cover plate (73) and the main mold (71) are assembled so that the boss (732) is inserted into the cavity, the boss (732) extrudes part of the injection liquid from the liquid discharge hole (733), and the rest of the injection liquid fills the space between the mold cover plate (73) and the main mold (71).

4. The method for preparing a self-adjusting binding force flexible electronic system according to claim 3, wherein the residual injection molding liquid is vacuumized to remove air bubbles therein.

5. A method for manufacturing a self-adjusting binding force flexible electronic system according to claim 3, wherein the main mold (71) has a groove (711), the groove (711) is located in the recessed space (712), the combination mold (72) is mounted to the groove (711), and the combination mold (72) is supported by the bottom wall of the groove (711) and is flush with the opening of the groove (711).

6. A method for manufacturing a self-adjusting binding force flexible electronic system according to claim 3, wherein the mould cover plate (73) and the main mould (71) have a male and female positioning assembly, and the stud (732) is located in the middle of the cavity under the positioning of the male and female positioning assembly.

7. Method for the preparation of a self-adjusting binding force flexible electronic system according to claim 3, characterized in that in the step of preparing the binding body mold (72) by means of photolithography, it comprises the following steps:

preparing a substrate;

first photoetching: forming a plurality of annular etching areas on the substrate by adopting a photoetching process;

and (3) second photoetching: forming a plurality of circular etching areas in the annular etching area on the substrate by adopting a photoetching process again, wherein the outer diameter of the circular etching areas is the same as that of the annular etching areas;

the substrate thus has a plurality of recessed regions (721), the recessed regions (721) having a central recessed depth smaller than the recessed depth of the edges.

8. The method for preparing a self-adjusting bonding force flexible electronic system according to claim 3, wherein the step of preparing a deformed flexible substrate comprises the steps of:

preparing PDMS mixed liquid for preparing the combined flexible substrate (11) and PDMS mixed liquid for preparing the liquid cavity flexible substrate (12), so that the proportion of curing agents in the PDMS mixed liquid for preparing the combined flexible substrate (11) is smaller than that of curing agents in the PDMS mixed liquid for preparing the liquid cavity flexible substrate (12);

bonding the flexible substrate (12) and the bonded flexible substrate (11) to seal the liquid chamber (2).

9. The method for manufacturing a self-adjusting binding force flexible electronic system according to claim 1, wherein the heating device (4) comprises a heating circuit, the heating circuit is manufactured by a photolithography process, and then the heating circuit is combined with the deformed flexible substrate by a transfer process.

10. The method for fabricating a self-adjusting bonding force flexible electronic system according to claim 9, wherein the flexible electronic system comprises a functional device (6), the functional device (6) comprises a functional circuit, the functional circuit is fabricated using a photolithography process, and after bonding the heat generating circuit with the deformed flexible substrate:

and pouring injection molding liquid on the heating circuit, combining the functional circuit with the injection molding liquid, pouring injection molding liquid on the functional circuit, and after the injection molding liquid is solidified, integrating the functional circuit and the heating circuit into a whole and packaging the integrated circuit.

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