KR101998019B1 - Dual-response actuators that maintain deformation under powerless conditions - Google Patents

Abstract

The present invention relates to a dual response soft actuator in which deformation is maintained in a powerless state and more particularly to a dual response actuator that causes deformation in response to two stimuli, .

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an ultra-low-power automatic-locking soft actuator,

The present invention relates to a dual response soft actuator in which deformation is maintained in a powerless state and more particularly to a dual response actuator that causes deformation in response to two stimuli, .

In recent years, interest in soft robots has increased as the public demand for robots similar to those shown in movies increases. ^1-3 Thus, by specific external stimuli such as octopus, ¹⁵ larvae, ¹⁶ some plants ^17,18 as observed in electricity, ^6,7 rows, ^8,9 light, ^10,11 pH change ^12,13 and pressure ¹⁴ There is considerable interest in the mechanical deformation of polymeric actuators showing mechanical deformation. ^{4 -5}

Among the various types of stimuli that can be used, the ion current (i.e., voltage) is similar to the stimulus that drives the muscles of the human body. In this regard, ionic polymer actuators are likely to be biomimetic devices that can be integrated into humanoid robots and artificial muscles. ^{19 -28} It is due to the low operating voltage of a few V, a simple fabrication process and a low price, which is a hallmark of ionic polymer actuators.

However, this technique is still in its infancy and attempts have been made to improve the operating performance of ionic polymer actuators. For example, the development of advanced ionic polymers to form well-ordered ionic channels to enable fast ion diffusion, ^22-26 an essential increase in dielectric constant to facilitate dissociation of ions at low activation potentials, ²⁷ There is an improvement in mechanical strength to achieve a high stress / strain rate. ^{26 , 27 , 29} These studies have consequently contributed to reducing actuator response time and increasing electromechanical deformation.

While significant progress has been made in the design of ionic polymers and the development of innovative actuators, it is necessary to develop actuators that consume low power. This is because, according to the basic operation principle of an actuator requiring high power, it requires a constant power supply to maintain the operation of the actuator. To reduce the power consumption of the actuator, several studies have been conducted focusing on reducing the operating voltage. ^{26, 27, 30, 31}

The present inventors have also disclosed an electroactive actuator comprising a polymer electrolyte in which an ionic liquid is covalently bound to a self-assembling block copolymer composed of a conductive block and a nonconductive block in Korean Patent No. 1477387 .

Unfortunately, these techniques are not ideal solutions because the movements of the actuators associated with the grapples are difficult to achieve without requiring external power supplies and can not lead to "true low power actuators."

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The problem to be solved in the present invention enters, the nature is observed in the living organism in response to changes in the environment that causes the asymmetric volume change double-layer structure, in particular ^32-34 trapping structure fly is formed by the leaves in order to provide a low-power actuator To provide a robust and functional bi-layer actuator responsive to one or more external stimuli, such as a magnetic lock action ^{34 -35} found in a natural structure such as a closed flight case, and more importantly, will be.

In order to solve the above problems,

There is provided a dual response actuator in which an electroactive polymer actuator and an asymmetric photoactive polymer actuator are laminated.

In the present invention, the asymmetric photoactive polymer actuator is caused to shrink by a light stimulus for irradiating light, and the polymer contracted by the removal of a light stimulus returns to a state before shrinkage.

In the present invention, the asymmetric photoactive polymer actuator is bonded to the surface contracted by the electro-active activity so that the electro-active actuator can maintain its contracted state for a long time.

'Asymmetric photoactive polymer actuator' means that the rate of polymer displacement due to the optical stimulus is substantially greater than the rate of recovery of the polymer displacement due to the removal of the optical stimulus.

'Substantially larger' means that the rate of polymer displacement due to the optical stimulus is 10 times, preferably 100 times, more preferably 1000 times or more faster than the rate of polymer displacement due to the removal of the polymer displacement by the removal of the optical stimulus .

In the present invention, the electroactive polymer actuator and the photoactive polymer actuator may be in the form of a film or a thin film, and may be bonded by coating or adhesion.

In the present invention, it is preferable that the photoactive polymer actuator is formed on the electrode surface of the electroactive polymer actuator so that the electrode of the electroactive polymer actuator does not interfere with the light stimulus.

In the present invention, since the increase in thickness due to the introduction of the photoactive polymer actuator into the photoactive polymer actuator may interfere with the operation of the entire actuator, the surface of the photoactive polymer actuator may be coated on the surface of the photoactive polymer actuator, , It is preferable to form a minute pattern of a simple cubic shape to increase the displacement.

In the practice of the present invention, the fine pattern is preferably a cubic pattern having an excellent rate of displacement increase.

In the present invention, the asymmetric photoactive polymer actuator may be an asymmetric blue active polymer actuator which is displaced by illumination of blue light. The blue light may be blue light in the range of 450 +/- 10 nm.

In the practice of the present invention, the asymmetric blue active polymer actuator may include a polymer in which isomerization occurs by light irradiation and a displacement, for example, a change in length occurs due to isomerization. The isomerization may be isomerization from trans form to cis form and may be isomerization from cis form to trans form.

In the present invention, the polymer in which displacement occurs due to isomerization may include an azobenzene-based compound whose length is reduced while isomerization from the trans is generated by irradiation of blue light.

In the practice of the present invention, the azobenzene compound may be crosslinked to the polymer network.

In a preferred embodiment of the present invention, the asymmetric blue active polymer actuator is a 4-Amino-1,1'-azobenzene-3,4'-dicyclohexylammonium chloride (PAAm-co-PDADMAC) disazoic acid monosodium salt (AAZO) may be an AAZO / PAAm-co-PDADMC crosslinked through ionic bonds.

In the present invention, the electroactive polymer actuator may be a self-assembling block copolymer on which an ionic liquid is supported to provide an ion conduction path which is well connected to each other to improve a response to an electric field.

In the practice of the present invention, the electroactive polymer actuator may be a poly (styrene sulfonate-b-methylbutylene-b-styrenesulfonate) (PSS-PMB-PSS) triblock copolymer.

In the practice of the present invention, the electroactive polymer actuator may be an actuator in which electrodes such as SWCNTs are laminated on both surfaces of a polymer thin film bent by electro-activity.

In order to overcome the limitations of the electroactive polymer actuator in order to overcome the limitations of the electroactive polymer actuator, the double response actuator which is operated by the electric field and the blue light by coating one surface of the electroactive polymer actuator with a macromolecule which causes volume contraction in response to blue light, As shown in Fig. 1, a large change in displacement can be obtained by reacting with the electric field and the blue light, respectively. Furthermore, since the shrinking volume returns very slowly when the light source is removed, the volume of the macromolecule that responds to the specific wavelength of blue light is very slow. Therefore, even if the energy source applied to the actuator is completely removed, . Locking is expected to consume less energy when applied to artificial muscles.

The present invention, in one aspect,

Wherein the actuator is displaced by irradiating electricity and light to the double response actuator in which the electroactive polymer actuator and the asymmetric photoactive polymer actuator are laminated, and the displaced actuator is locked by removing electricity and light. to provide.

This paper reports a new low power soft actuator based on a dual layer polymer actuator that reacts to light and voltage and can lock its operation for several minutes even without a power supply. The uniqueness of this actuator represents a high strain of 2.0% and consumes only 6.2 mWh / cm ² of power to hold the object for 15 at an operating voltage of 3 V. This is the first example of a self-locking soft actuator that can be operated with a small battery and can be used extensively in a wide variety of soft electronics applications.

Accordingly, a new low-power actuator that can be operated by light and electricity and minimizes power consumption in a grab state is provided by the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of an embodiment of the present invention, which is a chemical structural formula, wherein a, a sulfonated triple copolymer, b, an ionic liquid, HmImBF ₄ , c, 4-amino-1,1'-azobenzene-3,4'- disulfonic acid monosodium salt, poly (acrylamide-diallyldimethylammonium chloride) random copolymer.
2 is a schematic representation of a LEAP actuator. a, EAP layer and LAP layer to represent LEAP actuator, b, LEAP actuator, hold (hold), and self lock (power off) operations.
Figure 3 illustrates the operation of a voltage, light reaction actuator. In order to compare the bending strain with time at 3 V voltage of a LEAP actuator and a blue light of 455 nm wavelength, the EAP transducer was expressed under the same conditions. The photograph on the right panel shows that the LEAP actuator can hold an object three times heavier than the EAP actuator. b, bending strain of the LEAP actuator over time in response to UV radiation at an alternating square wave voltage of ± 3 V and a wavelength of 455 nm. Long-lasting and reversible motion was observed.
4 is a LEAP actuator having a micropattern. a, voltage application of cubic patterned LEAP actuator to LAP layer and bending deformation according to time by blue light irradiation. The embedded graph shows the amount of power consumed by the LEAP actuator during hold, hold, and lock operations over three minutes compared to the EAP actuator. b shows the bending displacement of the LAP thin film with independently produced micropatterns by blue light irradiation. c. Bonding Characteristics of LEAP Actuator with Cubic Pattern on LAP Layer after Curing.
5 shows the function and versatility of the LEAP actuator. a, Snapshots show the holding, locking, and dropping action of the LEAP actuator under voltage, blue stimulus. b, EAP actuators, and magnetic lock actuators.
6 is a morphology of an electroactive polymer thin film. 3q *, √4q *, √7q *, √9q *, √11q *, √12q *, and √12q * in the figure are the SAXS profiles at room temperature of the HmImBF ₄ loaded PSS-b-PMB- The Bragg peak indicated by (▼) denotes a cylindrical structure arranged in a hexagon. The size of the domain is 22 nm.
Figure 7 shows isomerization of the light active polymer. UV-vis spectroscopic spectra of ion-bonded crosslinked light active polymer (4-amino-1,1'-azobenzene-3,4'-disulfonic acid monosodium salt and poly (acrylamide-diallyldimethylammonium chloride) random copolymer) Lt; / RTI > It can be seen that the isomerization of LAP from trans to cis by the blue light of 455 nm rapidly occurs. On the other hand, when the blue light is turned off, isomerization from cis to trans occurs slowly over several hours.
8 is a SEM photograph of a LEAP actuator having a micropatterned LAP. For the production of the LEAP actuator, an EAP actuator consisting of an EAP layer sandwiched between carbon nanotube electrodes was stacked with a LAP of about 15 μm thick. The thickness of the EAP layer and the carbon nanotube electrode is ca. 30 [mu] m and 10 [mu] m. Several types of micropatterns with the same pitch and height of 8 μm were introduced into the LAP. Representative cross-sectional SEM images of LEAP actuators with cubic-pattern LAP and linear pattern LAP are labeled a and b, respectively.
9 is a volume change of the LAP having a cubic pattern by blue light. The optical microscope image reduces the volume of the engraved portion of the LAP layer of the cubic pattern by about 20% with blue light illumination. This is due to the morphological change from the trans state to the cis state of the azo component of the LAP layer.

Hereinafter, the present invention will be described in detail with reference to examples. The following examples are intended to illustrate the invention and are not intended to limit the invention.

summary

It is known that the biostratigraphy of natural systems observed in living organisms shows an asymmetric volume change due to environmental factors. A typical example of this is the unique trap structure that is activated by one stimulus. We have developed a dual-layered actuator based on light and electroactive polymer (LEAP). The LEAP actuator exhibits 250% better displacement and can lift an object three times heavier than conventional EAP. The most interesting point is that the bending motion of the LEAP actuator can be effectively maintained for tens of minutes even without a power supply. This is unprecedented. The self-locking LEAP actuator also exhibited a large reversible deformation of more than 2.1%, requiring only 6.2 mW / cm2 of power to hold the object for 15 minutes at an operating voltage of 3 V. With this new motion-locked soft actuator, you can find a wide range of applications for artificial muscle, biomedical microdevices, and a variety of innovative soft robot technologies.

Example

Sulfonated  Triblock copolymer .

(PSS-b-PMB-b-PSS) tri-block copolymer was synthesized according to the procedure described in the literature.

1.1. PS-PI-PS Tri-Block Copolymer Synthesis and Hydrogenation

The PS-PMB-PS triblock copolymer was synthesized by anionic polymerization using styrene (S) and isoprene (I) monomers. As a result, a PS-PI-PS triblock copolymer is obtained and then methylbutylene (MB) is synthesized by selective hydrogenation reaction to isoprene. Styrene is stirred in calcium hydride for 12 hours, transferred to a vacuum distillation reactor containing n-butyl lithium, and further purified by stirring for 6 hours. The isoprene is stirred in dibutyl magnesium for 3 hours and then transferred to a vacuum distillation reactor containing n-butyl lithium and refined by stirring for 6 hours. The polymerization is carried out using cycloheane as a solvent, and the purified monomers are transferred to a vacuum distillation reactor. Sec-butyl lithium was used as the initiator. The polymerization of styrene was first carried out at 45 ° C. for 4 hours, and then isoprene was added successively at the same temperature for 4 hours. Styrene was added thereto for 4 hours at the same temperature Go ahead. As a result, PS-PI-PS was obtained, and then selective hydrogenation of isoprene was carried out at 80 ° C. and 420 psi in a 2 liter Parr batch reactor with uniform Ni-Al catalyst. For the Ni-Al catalyst, 50 ml of Nickel 2-ethylhexanoate dissolved in cyclohexane at a concentration of 0.1 M is prepared at a concentration of 1.0 M using triethylaluminum dissolved in heptane. After the reaction, the reaction mixture was stirred vigorously with citric acid dissolved in water at a concentration of 10% to remove the catalyst. As a result of selective hydrogenation reaction to isoprene, methylbutylene is the product, and the polymer is PS-PMB-PS triblock copolymer. The polymer was analyzed by gel permeation chromatography (GPC, Waters Breeze 2 HPLC) and nuclear magnetic resonance (NMR) spectroscopy (Bruker AVB-300) ) Were measured. A solution of standard PS in tetrahydrofuran (THF) was used for calibration and the molecular weight distribution was less than 1.06.

1.2. PS-PI-PS Sulfonation  reaction ( Sulfonation )

The following procedure was carried out for the partial sulfonation of the styrene chain of PS-PMB-PS. Prepare 1 g of PS-PMB-PS in 40 ml of 1,2-dichloroethane in a 100 ml three-necked flask. The inlet is equipped with a condenser and a dropping funnel where the cooling water is refluxed. The mixture was heated to 40 占 폚, the inside of the reactor was filled with nitrogen gas to make it inactive, and stirred at the same time to dissolve the copolymer. To make acetic sulfate, 1.8 ml of Acetic anhydride is dissolved in 5.4 ml of dichloroethane. Cool the solution to 0 ° C and add 0.5 ml of 96% sulfuric acid. The resulting acetic sulfate is immediately added to the reactor through a dropping funnel attached to the reactor. The reaction time was adjusted to adjust the degree of sulfonation, and the reaction was terminated by adding 20 ml of 2-propanol at 50 mol% of the sulfonation degree. The resulting PSS-PMB-PSS was analyzed by Nuclear Magnetic Resonance (NMR) (Bruker AVB-300) and found to have a degree of polymerization of 118 (styrene), 348 (methylbutylene), and 122 The molecular weight of each block of the PSS-PMB-PSS polymer corresponds to 12.289, 25.108, 12.706 (kg / mol).

The molecular weight, block composition and degree of sulfonation of the PSS-b-PMB-b-PSS triblock copolymer were controlled to optimize the ionic conductivity (i.e., bending strain of the actuator) and mechanical strength (i.e., blocking force of the actuator).

The degree of polymerization of the block is a gel permeation chromatography (GPC, Waters Breeze 2 HPLC) with which standard polystyrene dissolved in a ¹ H nuclear magnetic resonance spectroscopy (Bruker AVB-300) and a specimen produced when tetrahydrofuran (THF) in CDCl ₃ The analysis based on the analysis is integrated. The GPC is measured before the second and third blocks are grown. The polydispersity index (PDI) of the triblock copolymer measured on GPC before the sulfonation reaction was 1.06. The degree of sulfonation of the PSS-b-PMB-b-PSS tri-block copolymer was analyzed by ¹ H-NMR at acetone-d ₆ .

Electro-active PSS -b- PMB -b- PSS  ≪ / RTI >

PMB-b-PSS triple block copolymer and 1-Hexyl-3-methylimidazolium tetrafluoroborate (HmImBF4, ≥ ≥ 97% HPLC grade, Sigma-Aldrich) in a predetermined volume of 80/20 vol.% THF / Make a 5 wt.% Solution in the methanol mixture. A film about 80 μm thick was prepared by solven-casting the aluminum mold (area 1 cm x 1.5 cm) for 2 days at room temperature under an argon atmosphere, followed by vacuum drying at 70 ° C for 7 days. The thickness of the dried polymer membrane was further controlled by hot press at 200 kgfcm ^-2 and 40 ° C. We investigated the shape of the polymer membrane produced by accelerator incineration X-ray scattering (SAXS) experiments using the PLS-II 3C SAXS beam line at the Pohang Accelerator Laboratory.

Light-activated azobenzene  Including polymer synthesis.

475 mg of 4-amino-1,1'-azobenzene-3,4'-disulfonic acid monosodium salt (Sigma-Aldrich, purified by recrystallization) and 50 mL of poly (acrylamide-co- diallyldimethylammonium chloride (Sigma-Aldrich, 2.5 wt.% in water) was added dropwise with stirring for 6 hours. The resulting polymer solution was purified by repeated dialysis and concentrated to 5 mL.

EAP  Fabrication of Actuator and LEAP Actuator .

The EAP actuator was first fabricated by interposing an electroactive PSS-b-PMB-b-PSS polymer between two carbon nanotube (CNT) electrodes. The CNT electrode was prepared by dissolving 33 mg of a single-walled carbon nanotube (SWCNT, Sigma-Aldrich by CoMoCAT catalytic CVD process), 82 mg of HmImBF ₄ and 50 mg of PVdF-HFP (Kynar Flex 2801, Arkema Chemical Inc.) , N-dimethylacetamide (≥≥99.9% HPLC grade, Sigma-Aldrich). The solution was ultrasonically mixed for 6 hours, cast on a glass plate (2 cm x 2 cm) at room temperature and then vacuum dried at 80 ° C. A CNT electrode having a thickness of approximately 10 mu m was obtained. For the production of dual-reacted LEAP actuators, a light active polymer (LAP) was further laminated to the EAP actuator. To pattern the LAP layer, a poly (dimethylsiloxane) (PDMS) template with various fine patterns was prepared from a mixture of 10/1 wt.% SYLGARD silicone elastomer 184 and its curing agent (Dow Corning Corp.). 10 mg of concentrated solution containing LAP was dropped onto a pre-cut EAP actuator (area of 15 mm x 5 mm) and covered with a pre-patterned PDMS mold. As pressure was applied, the channel of the PDMS was filled with LAP solution and vacuum dried in this state for 24 hours. After carefully removing the mold, the final structure of the LEAP actuator was confirmed by integrating a scanning electron microscope (SEM, Helios Nanolab 600) using a Zeiss microscope (AxioVision) and an acceleration voltage of 5 keV.

Actuator Performance test .

The EAP and LEAP actuator strips are fixed by two Pt disk electrodes and have a free length of 9 mm from the Pt contact. The flexural deformation of the actuator was evaluated using ± 3 V (VersaSTAT3, Princeton Applied Research, AMETEK Inc.) and / or 455 nm blue light (LED4D007, Thorlabs Inc.) in a laboratory environment. The displacement of the actuator over time under a given stimulus was recorded using a Zeiss microscope equipped with a charge coupled device camera (AxioVision). The displacement (?) Was converted to the bending strain (?) Based on? = ² ? D / (L ² +? ² ). L is the free length from the Pt contact and d is the thickness of the actuator. For the gripper test, three finger grippers were fabricated by placing three LEAP actuators vertically between two copper electrodes. The gripper irradiated blue light from the top to the bottom. The objects were glass beads, teflon, wine glasses and so on.

Actuators that respond to light and voltage

FIGS. 1A and 1B are chemical structural formulas of a polymer reacting with electricity, and FIGS. 1C and 1D respectively show a chemical structural formula of a polymer reacting with light, which constitute a magnetic lock actuator. 1-hexyl-3-methylimidazolium tetrafluoroborate (HmImBF₄) Was supported on the surface of the electroactive polymer to form an electroactive polymer. The electroactive polymer (EAP) has a well-aligned nano-sized hexagonal column structure This structure enables fast ion movement within the electric field. FIG. 6 shows the X-ray small angle scattering (SAXS) experiment result of EAP. A mixture of 4-amino-1,1'-azobenzene-3,4'-disulfonic acid monosodium salt and poly (acrylamide-diallyldimethylammonium chloride) random copolymer was introduced as a light-sensitive polymer. They form ionic crosslinks in the mixed state to improve the mechanical strength.

As shown in FIG. 2, a dual-response actuator was fabricated by using an electroactive polymer (EAP) and a light active polymer (LAP). LAP was deposited on the electroactive polymer actuator with the electroactive polymer sandwiched between the two CNT electrodes. The thicknesses of the LAP layer, the EAP layer, and the CNT electrode are 15 μm, 115 μm, and 10 μm, respectively. The size of the actuator is 4 mm (width) x 10 mm (length). Light active / electro-active actuators are now referred to as LEAP actuators. The LEAP actuator swings rapidly by voltage and / or illumination. This may be due to ion-transfer in the EAP by voltage and / or trans-cis isomerization of LAP by blue light irradiation. In particular, the LEAP actuator remains deformed after the voltage and light stimulus are removed, locking the motion and maintaining its shape. This is because when the blue light is removed, the isomerization of LAP from cis to trans occurs slowly. In other words, isomerization from trans to cis of the light-sensitive polymer at the 455 nm wavelength of the light-sensitive polymer takes several hours from cis to trans when the blue light is removed, as opposed to the rapid (Figure 7). It should be noted that this automatic locking concept is only possible if the blocking force of the LAP layer is greater than the resilience of the EAP layer.

Actuator performance

3A shows the bending reaction by reacting with the time of the LEAP actuator under the condition of 3V voltage and 455 nm wavelength in a laboratory environment at room temperature. An EAP actuator without a LAP layer is shown for reference. A voltage of 3 V is applied to the LEAP actuator and equilibrates at a strain (e) of 0.6% within 60 seconds. This is due to the asymmetric shrinkage and expansion of the EAP layer due to the accumulation of BF ₄ ^- anions near the anode surface and HmIm ⁺ cations near the cathode surface. The LEAP actuator was illuminated with blue light (l = 455 nm) while the voltage was applied. The e value rapidly increased to about 0.8% for 10 seconds and gradually stopped at the e value of 0.95%. This means that the LEAP actuator responds to both stimuli and the e value is increased by 150%. As a matter of fact, as in FIG. 3A, the illumination of the EAP actuator does not improve the operation of the actuator. LEAP actuators can lift objects three times heavier than EAP actuators because mechanical deformation increases in response to voltage and light stimuli. When the voltage stimulus is removed from the LEAP actuator, the e value decreases but decreases very slowly. In the case of the EAP actuator, the LEAP actuator decreases by 0.1% for 180 seconds, whereas in the first 15 seconds it decreases by 0.3%. More interestingly, the LEAP actuator remains effectively bent after removing both voltage and light stimuli (no external power supply). In the absence of external power, the e value decreased to less than 0.13% for 4 minutes and the actual e value was higher than 0.7%. This e value is again larger than the e value in the EAP actuator equilibrium state. The images embedded in FIG. 3A are representative photographs taken in each area. Making a finger with a LEAP actuator shows the self-locking behavior of the LEAP actuator when there is no power supply. 3B shows the reversible operation of the LEAP actuator with an alternating square wave voltage of < RTI ID = 0.0 > 3 V < / RTI > The self-locking behavior of the LEAP actuator lasted for an amazingly long period of time (more than 1000 seconds) when there was no power supply. However, when -3 V potential was applied, it quickly recovered to the initial state of the actuator. This shows that the actuator is made to fold and unfold by changing the voltage impulse.

High performance magnetic lock LEAP actuator as state-of-the-art actuator

It is worth noting that the operational performance of the LEAP actuator can be largely controlled by introducing a fine pattern in the LAP layer. Three types of fine patterns were introduced into the LAP layer: lines, concentric circles, the same pitch, and a cubic pattern with a height of 8 mm. Figure 8 shows a cross-sectional SEM image of a LEAP actuator with a micropatterned LAP layer. A LEAP actuator with a cubic patterned LAP layer exhibited an epsilon value of 2.1% under the same conditions (3 V voltage and 455 nm wavelength illumination). Compared with the EAP actuator, the operation performance is improved by 250%. Even when the same LAP and EAP materials are used for the two LEAP actuators, the performance of the LEAP actuator with the patternless LAP layer is twice that of the LEAP actuator (Fig. 3a). The patterned actuator showed an effective locking behavior even without a power supply and showed an epsilon value of 1.5% for 3 minutes after power was removed. The main goal of this study was the development of low-power actuators, and we directly compared the power consumption of the LEAP actuator with the power consumption of the EAP actuator. The results are shown in the embedded graph of FIG. 4A. To maintain bending motion for 3 minutes, the LEAP actuator required half the power at 3 V, the same as that used by the EAP actuator. In other words, the LEAP actuator required only 6.2 mW / cm2 to maintain an epsilon value of 1.5% for 3 minutes and the EAP actuator exhibited similar holding performance using 10.4 mW / cm2. It should be noted that the longer the holding time, the greater the difference in the amount of power consumed. For example, during a 5 minute hold time, the amount of power consumed by the two actuators is quadrupled. This result highlights the potential for applications of LEAP actuators in artificial muscle and biomedical microdevices due to their low power consumption. It is also known that the reduction in the amount of power consumed by only a few milliwatts is remarkable as compared with the conventional EAP actuator composed of a widely used polymer such as poly (vinylidene fluoride-co-hexafluoropropene) random copolymer (Kynar TM Flex 2801) It is important. The latter requires hundreds of milliwatts to some of the same wattage. Next, we describe the mechanism underlying the significantly enhanced performance of LEAP actuators with micropatterns.

The micropatterned LAP layer is used because the free space is large and the surface area is increased. In order to investigate the effect of micropattern on the operating performance, we evaluated the bending behavior in response to the light of the independently micropatterned LAP layer under blue illumination. The LAP strip has a length of 10 mm, a width of 5 mm and a thickness of 15 μm. As shown in FIG. 4B, the LAP layer with different fine patterns exhibited different bending displacements under blue light. The un-patterned LAP layer exhibited the smallest displacement of 1.1 mm. And increased to 1.6 mm (line), 2.7 mm (concentric circle) and 3.7 mm (cubic pattern) for the patterned LAP layer. This result shows that the stress / strain induced by the light-drive volume change in the LAP layer with fine pattern is different. It should be noted that introducing a fine pattern into the LAP layer not only increases the bending strain but also reveals interesting adhesion properties when the layer contacts the object. We have prepared three actuators: an EAP actuator, a patternless LEAP actuator, and a cubic patterned LEAP actuator. As shown in Fig. 4C, a quartz plate was placed in contact with the LAP layer on top of each of the three actuators (in the case of an EAP actuator, the SWCNT layer contacts the quartz plate). The blue light was then irradiated to the actuator for 1 minute. Only the LEAP actuator with the cubic LAP layer showed adhesive behavior when the quartz plate was lifted after turning off the blue light. The reason for this phenomenon is that the carved part of the cubic LAP layer is shrunk due to trans-cis isomerization. When the volume is reduced by about 20% (FIG. 9), the LAP layer sticks to the plate surface while the LAP layer re-expands when the blue light is turned off.

As far as we know, the concept of the self-locking motion described in this study and the demonstrated low-power operating performance have not been previously reported for any type of actuator, thus making the proposed actuator innovative.

Figure 5A is a series of snapshots illustrating that a LEAP actuator can grab and drop a wine glass based on the automatic locking mechanism proposed in this study. It consists of a LEAP actuator to implement easy grip (+3 V), lock (zero supply) and falling motion (-3 V) at any time. The duration or stimulation order of each stimulus did not affect the self-locking behavior of the LEAP actuator. As shown in FIG. 5B, the LEAP actuator operates as an EAP actuator when only a voltage stimulus is applied. However, a second stimulus, i.e., blue light, can be activated whenever necessary. The second stimulus not only improves the operating performance but also allows the actuator to maintain its own support structure even after the external power supply is removed

In summary, we have developed a low-power actuator that responds to voltage and light and has been classified as a "LEAP actuator". A key feature of the LEAP actuator is that it can exhibit self-locking behavior even without a power source. The basic mechanism of the LEAP actuator is a slow cis-trans isomerization process and a large blocking force generated by the light active polymer when the blue light is removed. Because of the ability to respond to both stimuli, the bending strain of the LEAP actuator can be much higher and more controlled. In addition, the surface topology of the light active polymer layer plays an important role in improving the operating performance and enables an adhesive property such as an octopus. LEAP actuators can hold objects for several minutes while consuming several milliwatts of power, which is significantly lower than tens to hundreds of milliwatts required by other actuators reported to date for similar fixation periods.

Claims (18)

Double Response Actuator with Electro - Active Polymeric Actuator and Asymmetric Photoactive Polymeric Actuator. The dual response actuator according to claim 1, wherein the asymmetric photoactive polymer actuator is configured to emit light by a light stimulus to emit light, and the polymer shrinked by light stimulus removal to return to a state before shrinkage. 3. The dual response actuator according to claim 1 or 2, wherein the asymmetric photoactive polymer actuator is bonded to a face contracted by electro-active activity. 3. The dual response actuator according to claim 1 or 2, wherein the electroactive polymer actuator and the photoactive polymer actuator are in the form of a film or a thin film. 3. The dual response actuator according to claim 1 or 2, wherein the photoactive polymer actuator is bonded to an electrode surface of the electroactive polymer actuator. 3. The dual response actuator according to claim 1 or 2, wherein the photoactive polymer actuator has a fine pattern on its surface. 7. The dual response actuator of claim 6, wherein the fine pattern comprises at least one of a line, a concentric circle, and a cubic shape. 7. The dual response actuator according to claim 6, wherein the fine pattern is a cubic pattern. 3. The dual response actuator according to claim 1 or 2, wherein the asymmetric photoactive polymer actuator is an asymmetric blue active polymer actuator. 3. The dual response actuator according to claim 1 or 2, wherein the asymmetric photoactive polymer actuator is isomerized by light irradiation. 11. The dual response actuator according to claim 10, wherein the isomerization of the compound contained in the polymer is converted from a trans form to a cis form. 12. The dual response actuator according to claim 11, wherein the compound contained in the polymer is an azobenzene-based compound. The method of claim 1, wherein the asymmetric photoactive polymer actuator is a 4-amino-1,1'-azobenzene-3,4'-disulfonic acid monosodium (PAAm-co-PDADMAC) network in a poly (acrylamide-co-diallyldimethylammonium chloride) wherein the salt (AAZO) is an AAZO / PAAm-co-PDADMC crosslinked through an ionic bond. 3. The dual response actuator according to claim 1 or 2, wherein the electroactive polymer actuator is a self assembled block copolymer having an ionic liquid supported thereon. 15. The dual response actuator of claim 14, wherein the electroactive polymer actuator is a poly (styrene sulfonate-b-methylbutylene-b-styrenesulfonate) (PSS-PMB-PSS) triple block copolymer. 3. The dual response actuator according to claim 1 or 2, wherein the electroactive polymer actuator is bent to one side by electro-active activity. Wherein the actuator is displaced by irradiating electricity and light to the double response actuator having the electroactive polymer actuator and the asymmetric photoactive polymer actuator bonded together, and the displaced actuator is locked by removing electricity and light. An artificial muscle using the dual response actuator of claim 1 or 2.

Images