Dielectric elastomer actuator and manufacturing method thereof

Abstract

The embodiment of the invention relates to a dielectric elastomer actuator. The dielectric elastomer actuator may include a dielectric elastomer layer, the dielectric elastomer layer including a dielectric elastomer. The dielectric elastomer may include a zwitterionic segment and a soft segment attached to the zwitterionic segment. The dielectric elastomer actuator may also include a first electrode and a second electrode. The dielectric elastomer actuator may also include one or more structural members. The dielectric elastomer actuator may be arranged such that in response to a potential difference applied between the first and second electrodes, a force is applied on the dielectric elastomer layer due to Maxwell stress, thereby moving the one or more structures.

Description

Cross-references to related applications

[0001] This application claims the benefit of priority to Singapore application No. 10202403600R, filed on 18 November 2024, the contents of which are incorporated herein by reference in their entirety for all purposes. Technical Field

[0002] Embodiments of this application relate to dielectric elastomer actuators. Embodiments of this application also relate to methods of manufacturing dielectric elastomer actuators. Background Technology

[0003] Flexible actuators are materials capable of large deformations, which can be driven by external stimuli to produce desired motion. Compared to conventional rigid robots and actuators, flexible actuators offer greater flexibility, adaptability, and compliance. Among various flexible actuators, dielectric elastomer actuators (DEAs) demonstrate great potential in flexible robotics applications due to their ability to achieve large deformations, fast response, and high energy density. Generally, a DEA consists of a dielectric elastomer (DE) layer disposed between two flexible electrodes, where an external voltage is applied to generate Maxwell stress, thereby altering the mechanical shape. In summary, the voltages used to drive DEAs are typically limited to several kilovolts, which severely restricts their applications. This is because state-of-the-art dielectric elastomers are constrained by low relative permittivity (also known as dielectric constant). For example, the dielectric constants of the three most commonly used dielectric elastomers are 2.8 for polydimethylsiloxane (PDMS), 4.7 for acrylic elastomers (very high bond (VHB) tape materials), and 7.0 for polyurethane (PU). To achieve satisfactory strain at relatively low voltages, dielectric elastomer materials with high dielectric constants and low elastic moduli are crucial, or in short, electromechanical sensitivity (…). High dielectric elastomer materials are crucial. However, it is worth noting that for practical DEA applications, low elastic modulus will result in low effective work, and dielectric elastomer materials with high dielectric constant and high breakdown field are highly favored.

[0004] Significant efforts have been devoted to improving the dielectric constant of dielectric elastomers. Numerous studies have shown that introducing conductive or highly permeable fillers (such as metal nanomaterials, carbon-based microparticles, conjugated polymers, liquid metals, ionic liquids, gel particles, barium titanate, titanium dioxide, boron nitride, etc.) can readily enhance the dielectric properties of dielectric elastomers. However, the introduction of fillers typically leads to a decrease in breakdown field strength and an increase in stiffness, which is detrimental to DEA applications. Meanwhile, according to percolation theory, the dielectric properties of composite materials remain dominated by the dielectric elastomer matrix. To address this fundamental problem, polar functional groups have been introduced into dielectric elastomers to improve the dielectric constant through dipole polarization effects. For example, high-performance polar fluorinated dielectric elastomers with high dielectric constants (10.23 measured at 1 kHz) have been developed for use in fast-moving flexible robots. Furthermore, it has been reported that a dielectric elastomer based on plasticized polyvinyl chloride was fabricated through C≡N interfacial polarization, exhibiting an excellent dielectric constant of 18.9 (measured at 1 kHz). Despite these encouraging results, dielectric elastomers with even higher dielectric constants remain lacking. Summary of the Invention

[0005] Embodiments of this application relate to a dielectric elastomer actuator. The dielectric elastomer actuator may include a dielectric elastomer layer comprising a dielectric elastomer. The dielectric elastomer may include a zwitterionic segment and a soft segment connected to the zwitterionic segment. The dielectric elastomer actuator may also include a first electrode and a second electrode. The dielectric elastomer actuator may also include one or more structural members. The dielectric elastomer actuator may be configured such that, in response to a potential difference applied between the first and second electrodes, a force due to Maxwell stress is applied to the dielectric elastomer layer, thereby moving the one or more structural members.

[0006] Embodiments of this application provide a method for manufacturing a dielectric elastomer actuator. The method may include manufacturing a dielectric elastomer layer comprising a dielectric elastomer. The dielectric elastomer may include zwitterionic segments and soft segments connected to the zwitterionic segments. The method may further include manufacturing or providing a first electrode. The method may further include manufacturing or providing a second electrode. The method may additionally include providing or manufacturing one or more structural members. The dielectric elastomer actuator may be configured such that, in response to a potential difference applied between the first and second electrodes, a force due to Maxwell stress is applied to the dielectric elastomer layer, thereby moving the one or more structural members. Attached Figure Description

[0007] In the accompanying drawings, the same reference numerals refer substantially to the same parts in different views. The drawings are not necessarily drawn to scale, but generally focus on illustrating the principles of various embodiments. In the following description, various embodiments of the invention are described with reference to the accompanying drawings.

[0008] Figure 1 A general illustration of a dielectric elastomer actuator according to different embodiments is shown.

[0009] Figure 2 A general illustration shows a method for manufacturing a dielectric elastomer actuator according to different embodiments.

[0010] Figure 3 (i) shows an example of a soft segment monomer / precursor, (ii) shows an example of a diisocyanate monomer, and (iii) shows an example of a zwitterionic monomer, which can be used to manufacture or synthesize zwitterionic dielectric elastomers according to different embodiments.

[0011] Figure 4 (i) shows the synthesis of two examples of zwitterionic monomers according to different embodiments, and (ii) shows the synthesis of one example of zwitterionic dielectric elastomer according to different embodiments.

[0012] Figure 5A A graph showing the dielectric constant as a function of frequency (in Hertz or Hz) illustrates the dielectric constant-frequency curves of zwitterionic dielectric elastomers with different zwitterionic contents according to different embodiments.

[0013] Figure 5B A graph showing dielectric loss as a function of frequency (in Hertz or Hz) is provided, illustrating dielectric loss-frequency curves for zwitterionic dielectric elastomers with different zwitterionic contents according to different embodiments.

[0014] Figure 5C A graph showing stress (in megapascals or MPa) as a function of strain (in percentage or %) illustrates stress-strain curves of zwitterionic dielectric elastomers with different zwitterionic contents according to different embodiments.

[0015] Figure 5D This diagram illustrates the modulus (in megapascals or MPa), dielectric constant, and electromechanical sensitivity (in megapascals or MPa) of zwitterionic dielectric elastomers with different zwitterionic contents according to various embodiments. -1 A comparison chart (unit: ).

[0016] Figure 5EA graph showing stress (in megapascals or MPa) as a function of strain (in percentage or %) is provided, illustrating stress-strain curves for newly manufactured samples and self-healing samples of zwitterionic dielectric elastomer ZPU-50 according to different embodiments.

[0017] Figure 5F A graph showing stress (in megapascals or MPa) as a function of strain (in percentage or %) is provided, illustrating stress-strain curves for fresh and recycled samples of zwitterionic dielectric elastomer ZPU-50 according to different embodiments.

[0018] Figure 6 This is a schematic diagram illustrating the operation of a pre-stretched buckling mode actuator according to different embodiments.

[0019] Figure 7 This is a schematic diagram illustrating the operation of a uniaxial pre-stretched bending mode actuator according to different embodiments.

[0020] Figure 8A The graph shows displacement (in millimeters or mm) as a function of electric field (volts / micrometer or V / µm). The graph compares the electric field-induced displacement of a bending mode actuator based on zwitterionic dielectric elastomer ZPU-50 according to different embodiments with the electric field-induced displacement of a conventional bending mode actuator based on very high bond (VHB) tape material and thermoplastic polyurethane (TPU).

[0021] Figure 8B A graph showing displacement (in millimeters or mm) as a function of electric field (volts / micrometer or V / µm) compares the electric field-induced displacement of a 1-stacked bending mode dielectric elastomer actuator with that of a 5-stacked bending mode dielectric elastomer actuator according to different embodiments. The inset shows a schematic diagram of a robotic gripper based on a 1-stacked bending mode dielectric elastomer actuator according to different embodiments.

[0022] Figure 8C It is based on different embodiments, Figure 8B An enlarged schematic diagram of the robotic gripper shown in the illustration.

[0023] Figure 8D A graph showing displacement (in millimeters or mm) as a function of the number of cycles illustrates the long-term stability of the actuation performance of a bending-mode dielectric elastomer actuator according to different embodiments.

[0024] Figure 8EThe diagram illustrates the operation of a robotic gripper based on a bending-mode dielectric elastomer actuator according to different embodiments.

[0025] Figure 9A A graph showing surface strain (in percentage or %) as a function of electric field (in volts per micrometer or V / µm) compares the surface strain performance of a buckling mode actuator based on zwitterionic dielectric elastomer ZPU-50 according to different embodiments with the surface strain performance of a conventional buckling mode actuator based on ultra-high viscosity (VHB) tape material and thermoplastic polyurethane (TPU), with insets illustrating the operation of the buckling mode actuator according to different embodiments.

[0026] Figure 9B The diagram illustrates the operation of a lifting device based on a buckling mode actuator according to different embodiments.

[0027] Figure 10A The diagram illustrates the coupling of a miniature robotic gripper for simultaneous sensing and actuation, according to different embodiments.

[0028] Figure 10B A schematic diagram showing the operating state of a miniature robotic gripper according to different embodiments.

[0029] Figure 10C The diagram illustrates capacitance (in arbitrary units or au) as a function of time (in seconds or s), showing the capacitive sensing signals during the up-and-down movement of a miniature robotic gripper based on zwitterionic dielectric elastomer (ZPU-50) and a robotic gripper based on commercial thermoplastic polyurethane (TPU) according to different embodiments.

[0030] Figure 10D The diagram illustrates capacitance (in any unit or au) as a function of time (in seconds or s), showing the capacitance sensing signals during opening and closing of a miniature robotic gripper based on zwitterionic dielectric elastomer (ZPU-50) and a robotic gripper based on commercial thermoplastic polyurethane (TPU) according to different embodiments.

[0031] Figure 10E The diagram illustrates capacitance (in arbitrary units or au) as a function of time (in seconds or s). It showcases miniature robotic grippers based on zwitterionic dielectric elastomer (ZPU-50) and those based on commercial thermoplastic polyurethane (TPU) according to different embodiments. Figure 10B The capacitive sensing signals are shown under different states. Detailed Implementation

[0032] The following detailed description refers to the accompanying drawings, which illustrate specific details and embodiments of the invention by way of illustration. These embodiments are fully described to enable those skilled in the art to practice the invention. Other embodiments may be used, and structural, logical, and electrical changes may be made without departing from the scope of the invention. Different embodiments are not necessarily mutually exclusive, as some embodiments may be combined with one or more other embodiments to form new embodiments.

[0033] Features described in the context of one embodiment may be correspondingly applied to the same or similar features in other embodiments. Features described in the context of one embodiment may be correspondingly applied to other embodiments, even if not explicitly described in those other embodiments. Furthermore, the application and / or combination and / or substitution described for features in the context of one embodiment may be correspondingly applied to the same or similar features in other embodiments. For example, embodiments described in the context of a dielectric elastomer actuator are equally applicable to other dielectric elastomer actuators. Similarly, embodiments described in the context of a method are equally applicable to dielectric elastomer actuators, and vice versa.

[0034] In the context of different embodiments, the articles “a,” “an,” and “the” used with respect to features or elements include references to one or more features or elements.

[0035] In the context of different embodiments, the term “about” or “approximately” applied to numerical values ​​covers both exact values ​​and reasonable differences, such as within 10% of a specified value.

[0036] As used herein, the term “and / or” includes any and all combinations of one or more of the related listed items.

[0037] The word "includes" means that it includes, but is not limited to, the content following the word "includes". Therefore, the use of the term "includes" indicates that the listed elements are necessary or mandatory, but other elements are optional and may or may not be present.

[0038] The phrase “composed of” includes and is limited to the content within the phrase “composed of”. Therefore, the phrase “composed of” indicates that the listed elements are necessary or mandatory, and that no other elements exist.

[0039] Figure 1A general illustration of a dielectric elastomer actuator according to various embodiments is shown. The dielectric elastomer actuator may include a dielectric elastomer layer 102, which includes a dielectric elastomer. The dielectric elastomer may include zwitterionic segments and soft segments connected to the zwitterionic segments. The dielectric elastomer may alternatively be referred to as a zwitterionic elastomer or zwitterionic polyurethane. The dielectric elastomer actuator may also include a first electrode 104a and a second electrode 104b. The dielectric elastomer actuator may also include one or more structural members 106. The dielectric elastomer actuator may be configured such that, in response to a potential difference applied between the first electrode 104a and the second electrode 104b, a force due to Maxwell stress is applied to the dielectric elastomer layer 102, thereby moving one or more structural members 106.

[0040] In other words, different embodiments may relate to a dielectric elastomer actuator having a layer 102 made of or comprising dielectric elastomer molecules having zwitterionic segments and soft segments. The dielectric elastomer actuator may also include a first electrode 104a, a second electrode 104b, and one or more structural members 106. In response to a potential difference applied between the first electrode 104a and the second electrode 104b, the layer 102 may be subjected to a force (e.g., pressure) generated by Maxwell stress, thereby actuating one or more structural members 106.

[0041] To avoid ambiguity, Figure 1 The purpose is to illustrate the various components of a dielectric elastomer actuator according to different embodiments, and is not intended to limit, for example, the shape, dimensions, size, arrangement, orientation, etc. of the various components.

[0042] The introduction of zwitterionic moieties provides the dielectric elastomer layer 102 with a larger dielectric constant and higher breakdown field strength. The dielectric elastomer layer 102 exhibits excellent surface strain and high energy density under weak electric fields. Under the same test conditions, the dielectric elastomer including the zwitterionic moieties demonstrates significantly superior test results compared to commercially available dielectric elastomers such as ultra-high viscosity (VHB) elastomers and thermoplastic polyurethane (TPU). The dielectric elastomer layer 102 can be actuated for over 1000 cycles while retaining more than 80% of its initial displacement. The required driving voltage or potential difference for the dielectric elastomer layer 102 is low, and this potential difference (applied to the dielectric elastomer layer 102 through the first electrode 104a and the second electrode 104b) can be equal to or less than 800V, for example, equal to or less than 500V.

[0043] Maxwell stress can be generated by an electrostatic or electric field caused by the potential difference applied between the first electrode 104a and the second electrode 104b. In different embodiments, the applied potential difference can cause the dielectric elastomer layer 102 to be compressed due to Maxwell stress, thereby causing strain in the dielectric elastomer layer 102 and consequently deformation of the dielectric elastomer layer 102. In contrast, some conventional actuators can employ different operating mechanisms, such as the thermally induced shape memory effect, the electrochemical capacitance effect (where mobile ions migrate on the film and cause different volume expansions at the electrodes), or a chemical effect manifested as a pH change, to induce changes in molecular structure.

[0044] Figure 1 The dashed lines indicate direct or indirect coupling between the dielectric elastomer layer 102 and one or more structural members 106. In different embodiments, one or more structural members 106 may contact the dielectric elastomer layer 102, or may be attached, coupled, or connected to the dielectric elastomer layer 102 via a first electrode 104a, a second electrode 104b, or any suitable intermediate component, member, or layer.

[0045] In various embodiments, the first electrode 104a and the second electrode 104b may be in contact with the dielectric elastomer layer 102. In various embodiments, the first electrode 104a may be a soft or flexible electrode. In various embodiments, the second electrode 104b may be a soft or flexible electrode. In various embodiments, the first electrode 104a and the second electrode 104b may be on opposite surfaces of the dielectric elastomer layer 102. The first electrode 104a and / or the second electrode 104b may comprise any suitable conductive material, such as graphene, carbon nanotubes, activated carbon, polyaniline, and / or polypyrrole.

[0046] In different embodiments, the dielectric elastomer actuator may be a lifting device, and one or more structural members 106 may be or may include a load, or may be or may include a hook or attachment member for suspending or carrying a load.

[0047] In different embodiments, the illustrated dielectric elastomer actuator can be a robotic gripper (e.g., a miniature robotic gripper), and one or more structural members 106 can be or may include pairs of grippers. Thanks to the stable signal generated by capacitive sensing, the robotic gripper or miniature gripper can synchronously achieve sensing and actuation at low voltages.

[0048] In various embodiments, the dielectric elastomer layer 102 may be configured as a capacitive sensor, such as a fringe field effect capacitive sensor. A fringe electric field can be generated when an induced voltage is applied between the first electrode 104a and the second electrode 104b. The first electrode 104a and the second electrode 104b may be electrically connected to a sensing circuit (e.g., an inductor-capacitor-resistor (LCR) meter). In various embodiments, the voltage source providing or generating the induced voltage and the voltage source configured to provide or generate a potential difference for actuation may be the same voltage source; in other various embodiments, the voltage source providing or generating the induced voltage and the voltage source configured to provide or generate a potential difference for actuation may be different voltage sources. In various embodiments, one or more structural members 106 may be conductive and electrically connected to the first electrode 104a and / or the second electrode 104b. For example, one or more structural members 106 may be paired grippers. When an induced voltage is applied between the first electrode 104a and the second electrode 104b, the first electrode 104a, the second electrode 104b, and / or one or more structural components 106 can generate an edge electric field. When different objects with different dielectric constants are located within the edge electric field, the capacitance measured by the induction circuit can change.

[0049] In various embodiments, the dielectric elastomer may further comprise one or more diisocyanate segments. Soft segments may be attached to or bonded to zwitterions via these one or more diisocyanate segments. Each of these one or more diisocyanate segments may be formed from a diisocyanate monomer, such as hexamethylene diisocyanate (HDI), 1,4-diisocyanatobutane, isophorone diisocyanate (IPDI), toluylene diisocyanate, 1,3-phenylene diisocyanate, diphenylmethane 4,4'-diisocyanate, or 1,4-phenylene diisocyanate.

[0050] The zwitterionic segment can be formed from a zwitterionic monomer, which is a molecule having both a cationic (positively charged) group and anionic (negatively charged) group. In different embodiments, the zwitterionic monomer may have a branched chain, which has an alkyl group (R4) and includes a sulfonate group (SO3). - ), carboxylate (CO2) - ) or phosphate (PO3) - The functional group of ). In different embodiments, the alkyl group (R4) may be bonded to a (cationic) group comprising a nitrogen atom and three R groups (i.e., R1, R2, and R3) attached to the nitrogen atom. R1 and R2 may be hydroxyalkyl, vinylalkyl, acrylate, etc., respectively. R3 may be alkyl, hydroxyalkyl, vinylalkyl, acrylate, etc. The zwitterionic monomer may be, for example, sulfobetaine 3-diol (SB3-diol) or sulfobetaine 4-diol (SB4-diol) zwitterionic monomers.

[0051] The soft segment can be formed from polytetramethylene ether glycol (PTMG), polycaprolactone diol, poly(propylene glycol) or polyethylene glycol.

[0052] Figure 2 This diagram illustrates a general illustration of a method for manufacturing a dielectric elastomer actuator according to various embodiments. The method may include manufacturing a dielectric elastomer layer comprising a dielectric elastomer at 202. The dielectric elastomer may include zwitterionic segments and soft segments connected to the zwitterionic segments. The method may further include manufacturing or providing a first electrode at 204. The method may further include manufacturing or providing a second electrode at 206. The method may additionally include providing or manufacturing one or more structural members at 208. The dielectric elastomer actuator may be configured such that, in response to a potential difference applied between the first and second electrodes, a force due to Maxwell stress is applied to the dielectric elastomer layer, thereby moving the one or more structural members.

[0053] In other words, embodiments of this application relate to the manufacture of the dielectric elastomer actuator described herein. The dielectric elastomer actuator may include a dielectric elastomer layer, a first electrode, a second electrode, and one or more structural components.

[0054] To avoid ambiguity, Figure 2 The purpose of this description is to illustrate the steps according to different embodiments and is not intended to limit the order of the steps. For example, step 202 may be performed before step 204, after step 204, or simultaneously with step 204.

[0055] In different embodiments, the dielectric elastomer may further include one or more diisocyanate segments. The soft segment can be connected to or bonded to the zwitterionic segment via the one or more diisocyanate segments.

[0056] In various embodiments, the dielectric elastomer can be manufactured by a polymerization process. In various embodiments, the dielectric elastomer can be manufactured by the following steps: mixing a zwitterionic monomer, a soft segment monomer / precursor, and a solvent (e.g., dimethylformamide (DMF), dimethyl sulfoxide, tetrahydrofuran, and / or dimethylacetamide) to form a mixture; heating the mixture at a first preset temperature (e.g., 80°C); and after cooling the mixture from the first preset temperature to a second preset temperature (e.g., room temperature or 20°C), applying one or more diisocyanate monomers and a catalyst (e.g., dibutyltin dilaurate (DBTDL), triethylenediamine, and / or stannous octoate) to the mixture.

[0057] The one or more diisocyanate monomers may be or may include any suitable diisocyanate monomers. For example, the one or more diisocyanate monomers may be selected from the group consisting of hexamethylene diisocyanate (HDI), 1,4-butane diisocyanate, isophorone diisocyanate (IPDI), toluene diisocyanate, 1,3-phenyl diisocyanate, diphenylmethane-4,4'-diisocyanate, and 1,4-phenyl diisocyanate.

[0058] The zwitterionic monomer can be any suitable zwitterionic monomer. In various embodiments, the zwitterionic monomer may have a branched chain having an alkyl group (R4) and a functional group including a sulfonate group (SO3). - ), carboxylate (CO2) - ) or phosphate (PO3) - In different embodiments, the alkyl group (R4) may be bonded to a (cationic) group comprising a nitrogen atom and three R groups (i.e., R1, R2, and R3) attached to the nitrogen atom. R1 and R2 may be hydroxyalkyl, vinylalkyl, or acrylate groups, respectively. R3 may be alkyl, hydroxyalkyl, vinylalkyl, or acrylate groups, etc. The zwitterionic monomer may be, for example, a sulfobetaine-3-diol (SB3-diol) or a sulfobetaine-4-diol (SB4-diol) zwitterionic monomer.

[0059] The soft segment monomer / precursor can be any monomer / precursor suitable for reaction with zwitterionic monomers and optionally one or more diisocyanate monomers. For example, the soft segment monomer / precursor can be polytetramethylene ether glycol (PTMG), polycaprolactone glycol, polypropylene glycol, or polyethylene glycol.

[0060] In various embodiments, the zwitterionic monomer can be produced by mixing a first precursor, a second precursor, and another solvent (e.g., acetonitrile) to form a solution and heating the solution to form the zwitterionic monomer. The first and second precursors can be any precursor suitable for producing the desired zwitterionic monomer. For example, the first precursor can be N-butyldiethanolamine, and the second precursor can be 1,3-propane sultone (used to produce the zwitterionic monomer of sulfobetaine 3-diol (SB3-diol)) or 1,4-butane sultone (used to produce the zwitterionic monomer of sulfobetaine 4-diol (SB4-diol)).

[0061] In various embodiments, the dielectric elastomer layer can be fabricated by depositing a dielectric elastomer using a suitable deposition process, selected from blade coating, spin coating, dip coating, spray coating, screen printing, inkjet printing, and three-dimensional (3D) printing. In various embodiments, the dielectric elastomer layer can be fabricated by depositing a dielectric elastomer on a first electrode or a second electrode. In other various embodiments, the dielectric elastomer layer can be fabricated by depositing a dielectric elastomer on a substrate, fabricating a first electrode in contact with the dielectric elastomer layer, removing the substrate, and fabricating a second electrode in contact with the dielectric elastomer layer.

[0062] In different embodiments, the potential difference can cause the dielectric elastomer layer to be compressed due to Maxwell stress, thereby causing strain in the dielectric elastomer layer and consequently deformation of the dielectric elastomer layer.

[0063] In different embodiments, the dielectric elastomer layer can also be configured to function as a capacitive sensor.

[0064] In different embodiments, one or more structural members may be or may include pairs of grippers, and the dielectric elastomer actuator may be a robotic gripper, such as a miniature robotic gripper. In other different embodiments, one or more structural members may be or may include a load, or may be or may include hooks or attachment members for suspending or carrying a load, and the dielectric elastomer actuator may be a lifting device.

[0065] Unlike materials that rely on a gradual increase in dielectric constant due to weak / moderate dipole moments, the inherent strong dipole moments of zwitterions can lead to a sharp increase in the dielectric constant of dielectric elastomers (DEs). Zwitterions possess extremely high dielectric constants (e.g., 200 to 270) in reported soft materials. Furthermore, the corresponding homopolymers have also been reported to have very high dielectric constants (approximately 150 @ 1 kHz). Partial copolymerization of zwitterions into elastomers can result in zwitterionic dielectric elastomers (DEs) with larger dielectric constants, higher breakdown field strengths, and higher maximum electrostatic energy densities than existing dielectric elastomers. Dielectric elastomer actuators (DEAs) according to various embodiments can exhibit excellent surface strain and high energy density under weak electric fields, significantly outperforming commercially available dielectric elastomers such as VHB and TPU. Notably, the dielectric elastomer actuators (DEAs) can be actuated for over 1000 cycles at a low drive voltage of only 500 V while retaining more than 80% of the initial displacement, demonstrating superior performance compared to existing dielectric elastomer actuators. Thanks to the stable signal generated by capacitive sensing, the gripper, according to different embodiments, can achieve simultaneous sensing and actuation at low operating voltages.

[0066] Zwitterionic elastomers can have the following advantages: (i) they exhibit good mechanical properties, such as strong tensile strength, high tensile strength, low modulus, and excellent toughness; (ii) they are self-healing and can be recycled through hot pressing or solution recovery; (iii) they benefit from the large dipole moment of zwitterions; the dielectric constant of zwitterionic elastomers is significantly greater than that of existing dielectric elastomer materials (e.g., zwitterionic liquids have a dipole moment of 35D to 41D compared to the 3.6D C≡N dipole moment in acetonitrile and the 4.47D dipole moment in dimethyl sulfone); the dielectric constant can also be adjusted by adjusting the zwitterionic... (iv) It can have a higher breakdown field strength than most reported dielectric elastomer materials because zwitterionic elastomers can be pure elastomers without fillers; (v) It can be actuated by lower voltages and has satisfactory actuation performance due to its high dielectric constant and satisfactory elastic modulus; (vi) It exhibits excellent stability during actuation, with no significant reduction in displacement due to its low viscoelasticity; (vii) It can exhibit a stable capacitive sensing signal when operating at low voltages; (viii) It has antifouling and antibacterial properties due to its hydrophilicity and repulsion of contaminants.

[0067] Amphoteric dielectric elastomers can be synthesized using different components such as soft segment monomers / precursors, diisocyanates, zwitterionic monomers, acrylates, etc. Figure 3(i) shows an example of a soft-segment monomer / precursor, (ii) shows an example of a diisocyanate monomer, and (iii) shows an example of a zwitterionic monomer that can be used to manufacture or synthesize zwitterionic dielectric elastomers according to different embodiments. The soft-segment monomer / precursor may be, for example, polytetramethylene ether glycol (PTMG), polycaprolactone glycol, polypropylene glycol, or polyethylene glycol. The diisocyanate monomer may be, for example, hexamethylene diisocyanate (HDI), 1,4-butane diisocyanate, isophorone diisocyanate (IPDI), toluene diisocyanate, 1,3-phenylene diisocyanate, diphenylmethane 4,4'-diisocyanate, or 1,4-phenylene diisocyanate. The zwitterionic monomer may have a branched chain having an alkyl group (R4) and a functional group including a sulfonate group (SO3). - ), carboxylate (CO2) - ) or phosphate (PO3) - In different embodiments, the alkyl group (R4) may be bonded to a (cationic) group comprising a nitrogen atom and three R groups (i.e., R1, R2, and R3) attached to the nitrogen atom. R1 and R2 may be hydroxyalkyl, vinylalkyl, or acrylate groups, respectively. R3 may be an alkyl, hydroxyalkyl, vinylalkyl, or acrylate group, etc. The zwitterionic monomer may be, for example, a sulfobetaine 3-diol (SB3-diol) zwitterionic monomer or a sulfobetaine 4-diol (SB4-diol) zwitterionic monomer. For the avoidance of doubt, Figure 3 The purpose is to provide examples of choices of usable components, and in different embodiments, the following can be used. Figure 3 The zwitterionic dielectric elastomers according to different embodiments are made or synthesized using materials or components not listed herein. Additionally, the following examples are not intended to limit the invention.

[0068] Example 1: Manufacturing of zwitterionic monomers and zwitterionic dielectric elastomers (zwitterionic polyurethane, ZPU or ZPU)

[0069] Figure 4 (i) illustrates the synthesis of two examples of zwitterionic monomers according to different embodiments, and (ii) illustrates the synthesis of one example of a zwitterionic dielectric elastomer according to different embodiments. The molecular ratio of the zwitterionic monomer to the soft segment monomer / precursor can be adjusted to obtain different zwitterionic elastomers with different dielectric and mechanical properties. Reference Figure 4(i) To synthesize the zwitterionic monomer of sulfobetaine 3-diol (SB3-diol), 1,3-propanesulfonyl lactone (11.966 g, 98 mmol), N-butyldiethanolamine (17.38 g, 108 mmol), and acetonitrile (20 mL) were dissolved together in a round-bottom flask. The mixture was heated to reflux at 110 °C under an argon atmosphere and stirred for 24 hours. After the reaction was complete, the product was washed three times with diethyl ether. For the zwitterionic monomer of sulfobetaine 4-diol (SB4-diol), 1,4-butanesulfonyl lactone (13.344 g, 98 mmol), N-butyldiethanolamine (17.38 g, 108 mmol), and acetonitrile (20 mL) were dissolved together in a round-bottom flask. The mixture was heated to reflux at 110 °C under an argon atmosphere and stirred for 24 hours. After the reaction was complete, the product was washed three times with diethyl ether.

[0070] Prior to polymerization, the soft segment precursor / monomer (e.g., polytetramethylene ether glycol (PTMG)) and zwitterionic monomer (e.g., SB3-diol / SB4-diol) are vacuum-dried overnight at 120°C to remove water. PTMG and SB3-diol / SB4-diol can be mixed in different molecular ratios (e.g., 75:25, 50:50, and 25:75). Zwitterionic polyurethanes manufactured with different PTMG:SB4-diol molecular ratios can be named ZPU-25 (75:25 ratio), ZPU-50 (50:50 ratio), and ZPU-75 (25:75 ratio), respectively. For example, to manufacture ZPU-50, PTMG (1.0 g, 1.0 mmol), SB4-diol (0.297 g, 1.0 mmol), and dimethylformamide (DMF) (3.5 mL) were first added to a glass vial and heated at 80 °C for 1 hour with stirring and argon bubbling. The mixture was cooled to room temperature, and diisocyanate monomers (e.g., isophorone diisocyanate (IPDI) (0.233 mL, 1.10 mmol), hexamethylene diisocyanate (HDI) (0.177 mL, 1.10 mmol)) and dibutyltin dilaurate (DBTDL) (40 μL) were added to the flask. The reaction mixture was stirred at 80 °C for 24 hours under an argon atmosphere.

[0071] Example 2: Dielectric and mechanical properties of zwitterionic dielectric elastomers

[0072] To study the dielectric and mechanical properties of different zwitterionic polyurethanes (ZPUs), dielectric constant, dielectric loss, and stress-strain curves can be plotted based on the measurement results.

[0073] Figure 5AA graph illustrating the dielectric constant as a function of frequency (in Hertz or Hz) shows the dielectric constant-frequency curves for zwitterionic dielectric elastomers with different zwitterionic contents according to different embodiments. For zwitterionic dielectric elastomers made from SB4-diol with gradually increasing zwitterionic contents (atomic percentages, at.%) of 25, 50, and 75 (i.e., ZPU-25, ZPU-50, and ZPU-75), at all measurement frequencies, the zwitterionic dielectric elastomers exhibit a high dielectric constant that increases with increasing zwitterionic content, with ZPU-25 having a dielectric constant of 14.2, ZPU-50 having a dielectric constant of 36.7, and ZPU-75 having a dielectric constant of 64.6 at 1 kHz.

[0074] Figure 5B A graph showing dielectric loss as a function of frequency (in Hertz or Hz) illustrates the dielectric loss-frequency curves for zwitterionic dielectric elastomers with different zwitterionic contents according to different embodiments. Although the dielectric constant of the zwitterionic dielectric elastomers is high, the dielectric loss remains at a relatively low level (0.251 for ZPU-25, 0.393 for ZPU-50, and 0.646 for ZPU-75 at 1 kHz), although the dielectric loss tends to increase with increasing zwitterionic content.

[0075] Figure 5C A graph showing stress (in megapascals or MPa) as a function of strain (in percentage or %) illustrates stress-strain curves of zwitterionic dielectric elastomers with different zwitterionic contents according to different embodiments. Figure 5D This diagram illustrates the modulus (in megapascals or MPa), dielectric constant, and electromechanical sensitivity (in megapascals or MPa) of zwitterionic dielectric elastomers with different zwitterionic contents according to various embodiments. -1 The comparison chart is in units of _____. Due to dynamic ionic interactions associated with the zwitterionic portion, based on tensile measurements, increasing the zwitterionic content leads to an increase in Young's modulus (Y), a decrease in tensile strength, and ultimately a decrease in toughness. Furthermore, all three zwitterionic dielectric elastomers (ZPUs) exhibit the strain hardening characteristics required for high-performance DEA.

[0076] The dynamic ionic interactions of zwitterions endow ZPU-50 with excellent self-healing and recyclability. The self-healing properties of ZPU-50 were evaluated based on tensile test results of the original sample and the repaired sample (heated at 80°C for different times after bisecting). Figure 5EA graph showing stress (in megapascals or MPa) as a function of strain (in percentage or %) is provided, illustrating stress-strain curves for newly manufactured samples and self-healing samples of zwitterionic dielectric elastomer ZPU-50 according to different embodiments. Figure 5E The results show that ZPU-50 can begin to recover its mechanical strength with increasing repair time, and a 24-hour repair time allows it to achieve excellent recovery rates of 92.48%, 86.29%, and 98.66% in tensile properties, tensile strength, and toughness, respectively. Tensile stress-strain curves of the ZPU-50 membrane before and after solution recycling were measured to demonstrate its excellent recyclability. Figure 5F A graph showing stress (in megapascals or MPa) as a function of strain (in percentage or %) is presented, illustrating stress-strain curves for fresh and recycled samples of the zwitterionic dielectric elastomer ZPU-50 according to different embodiments. Tensile testing shows that ZPU-50 maintains similar mechanical properties even after three solution recoveries, with only a slight decrease in tensile strength and elongation at break.

[0077] Example 3: Actuation performance of zwitterionic dielectric elastomer actuators

[0078] The actuation properties of zwitterionic dielectric elastomers are characterized by two different actuators: a buckling device without pretension and a bending device with uniaxial pretension. Figure 6 This is a schematic diagram illustrating the operation of a pre-stretch buckling mode actuator according to various embodiments. The device may include a stacked arrangement of a first electrode 604a, a second electrode 604b, and a dielectric elastomer layer 602 between two fixed frames or anchors 608a and 608b. When no potential difference is applied between the first electrode 604a and the second electrode 604b, the first electrode 604a, the second electrode 604b, and the dielectric elastomer layer 602 between them can be in a non-buckled state. When a potential difference is applied between the first electrode 604a and the second electrode 604b, the opposite charges in the first electrode 604a and the second electrode 604b can compress the dielectric elastomer layer 602, causing the dielectric elastomer layer 602 and the electrodes 604a, 604b to be in a buckled state.

[0079] Figure 7This is a schematic diagram illustrating the operation of a uniaxially pre-stretched bending mode actuator according to different embodiments. When a potential difference is applied between the first electrode 704a and the second electrode 704b, the first electrode 704a, the second electrode 704b, and the dielectric elastomer layer 702 between the first electrode 704a and the second electrode 704b can be in a non-bending state. When a potential difference is applied between the first electrode 704a and the second electrode 704b, the opposite charges in the first electrode 704a and the second electrode 704b can compress the dielectric elastomer layer 702, which causes the dielectric elastomer layer 702 and the electrodes 704a and 704b to be in a bending state.

[0080] for Figures 6 to 7 The two devices shown exhibit significantly superior actuation performance compared to actuators based on commercially available dielectric elastomers such as TPU and VHB tape.

[0081] Figure 8A The graph shows displacement (in millimeters (mm)) as a function of electric field (volts / micrometer or V / µm), comparing the electric field-induced displacement of a bending mode actuator based on zwitterionic dielectric elastomer ZPU-50 according to different embodiments with the electric field-induced displacement of a conventional bending mode actuator based on ultra-high viscosity (VHB) tape material and thermoplastic polyurethane (TPU). Figure 8B A graph showing displacement (in millimeters or mm) as a function of electric field (volts / micrometer or V / µm) compares the electric field-induced displacement of a 1-stacked bending mode dielectric elastomer actuator with that of a 5-stacked bending mode dielectric elastomer actuator according to different embodiments. The inset shows a schematic diagram of a robotic gripper based on a 1-stacked bending mode dielectric elastomer actuator according to different embodiments. Figure 8C It is based on different embodiments, Figure 8B The illustration shows an enlarged schematic diagram of a robotic gripper. The robotic gripper may include a first electrode 804a, a second electrode 804b, and a dielectric elastomer layer 802 between the first electrode 804a and the second electrode 804b. The robotic gripper may also include a pair of gripping elements 806a and 806b attached to the electrodes 804a and 804b. The first gripping element 806a may be attached to the first electrode 804a, and the second gripping element 806b may be attached to the second electrode 804b.

[0082] Figure 8D A graph showing displacement (in millimeters (mm)) as a function of the number of cycles illustrates the long-term stability of the actuation performance of a bending-mode dielectric elastomer actuator according to different embodiments. Figure 8EThe diagram illustrates the operation of a robotic gripper based on a bending-mode dielectric elastomer actuator according to different embodiments.

[0083] Figure 9A A graph showing surface strain (in percentage (%)) as a function of electric field (in volts per micrometer or V / µm) compares the surface strain performance of a buckling mode actuator based on zwitterionic dielectric elastomer ZPU-50 according to different embodiments with the surface strain performance of a conventional buckling mode actuator based on ultra-high viscosity (VHB) tape material and thermoplastic polyurethane (TPU), with insets illustrating the operation of the buckling mode actuator according to different embodiments. Figure 9B This diagram illustrates the operation of a lifting device based on a buckling mode actuator according to various embodiments. The lifting device may include a dielectric elastomer layer 902, a first electrode 904a on a first surface of the dielectric elastomer layer 902, and a second electrode 904b on a second surface of the dielectric elastomer layer 902 opposite to the first surface. The second electrode 904b may be attached to a load 912. When a potential difference is applied between the first electrode 904a and the second electrode 904b, the load 912 can be lowered. When no potential difference is applied, the load 912 can be raised.

[0084] Example 5: Proprioceptive gripper based on zwitterionic dielectric elastomer

[0085] One approach to achieving body sensing on a gripper is to utilize fringefield effect capacitive sensors. Since dielectric elastomer actuators (DEAs) are essentially capacitors, it is feasible to simultaneously sense and actuate the DEA during operation. This ability to simultaneously sense and actuate is even more critical for miniature grippers, as the size limitations of miniature grippers make the installation of other sensors difficult. Furthermore, capacitive sensing is highly sensitive to electromagnetic interference, especially at high voltages. Figure 10AThis diagram illustrates the coupling of a miniature robotic gripper for synchronous sensing and actuation according to various embodiments. The miniature robotic gripper may include a dielectric elastomer layer 1002, a first electrode 1004a on a first surface of the dielectric elastomer layer 1002, and a second electrode 1004b on a second surface of the dielectric elastomer layer 1002 opposite to the first surface. The miniature robotic gripper may also include gripping elements 1006a and 1006b attached to the electrodes 1004a and 1004b. The electrodes 1004a and 1004b can be electrically connected to a high-voltage source 1008 via wires for actuation. The resistance of the wires can be represented by resistive elements 1010a and 1010b. The electrodes 1004a and 1004b can be electrically connected to an inductor-capacitor-resistor (LCR) meter 1012. Capacitor element 1014 can be connected to electrodes 1004a, 1004b and LCR meter 1012 to eliminate the direct current (DC) component in the induced voltage before measurement by LCR meter 1012.

[0086] Figure 10B Schematic diagrams illustrating the operating states of a miniature robotic gripper according to different embodiments are shown. The miniature robotic gripper can be in a "high" position in operating states "1" and "4", and in a "low" position in operating states "2", "3", "5", and "6". Furthermore, the induced voltage can be turned on in operating states "1", "2", and "6", and turned off in operating states "3", "4", and "6". Figure 10C The diagram illustrates capacitance (in arbitrary units (au)) as a function of time (in seconds or s), showing the capacitance sensing signals during the up-and-down movement of a miniature robotic gripper based on zwitterionic dielectric elastomer (ZPU-50) and a robotic gripper based on commercial thermoplastic polyurethane (TPU) according to different embodiments. Figure 10D The diagram illustrates capacitance (in arbitrary units (au)) as a function of time (in seconds (s)) according to different embodiments, showing the capacitance sensing signals of a miniature robotic gripper based on zwitterionic dielectric elastomer (ZPU-50) and a robotic gripper based on commercial thermoplastic polyurethane (TPU) during opening and closing. Figure 10E The diagram illustrates capacitance (in arbitrary units or au) as a function of time (in seconds or s). It showcases miniature robotic grippers based on zwitterionic dielectric elastomer (ZPU-50) and those based on commercial thermoplastic polyurethane (TPU) according to different embodiments. Figure 10B The capacitive sensing signals are shown under different states.

[0087] Table 1 below shows a comparison of dielectric elastomers with other actuation devices.

[0088] Different embodiments based on zwitterionic dielectric elastomers can overcome the shortcomings of dielectric elastomers. The high voltage requirements of dielectric elastomers can be significantly reduced, while the finite lifetime of dielectric elastomers can be improved. Typical DEA (Dielectric Atomizer) usually requires a driving voltage of several kilovolts and has a limited lifetime. However, different embodiments based on zwitterionic dielectric elastomers can significantly reduce the required driving voltage and improve cycle stability.

Claims

1. A dielectric elastomer actuator, comprising: A dielectric elastomer layer, the dielectric elastomer layer comprising a dielectric elastomer, the dielectric elastomer comprising a zwitterionic segment and a soft segment connected to the zwitterionic segment; First electrode; Second electrode; as well as One or more structural components; The dielectric elastomer actuator is configured such that, in response to a potential difference applied between the first electrode and the second electrode, a force is applied to the dielectric elastomer layer due to Maxwell stress, thereby moving the one or more structural members.

2. The dielectric elastomer actuator according to claim 1, The potential difference causes the dielectric elastomer layer to be compressed due to Maxwell stress, which in turn causes strain in the dielectric elastomer layer, and consequently deformation of the dielectric elastomer layer.

3. The dielectric elastomer actuator according to claim 1 or 2, The one or more structural members include a pair of grippers; and The dielectric elastomer actuator mentioned above is a robotic gripper.

4. The dielectric elastomer actuator according to claim 1 or 2, The one or more structural components include loads; and The dielectric elastomer actuator is a lifting device.

5. The dielectric elastomer actuator according to claim 1, The dielectric elastomer layer is also configured to function as a capacitive sensor.

6. The dielectric elastomer actuator according to claim 1, The dielectric elastomer further includes one or more diisocyanate segments.

7. The dielectric elastomer actuator according to claim 1, The soft segment is formed from polytetramethylene ether glycol, polycaprolactone glycol, polypropylene glycol, or polyethylene glycol.

8. The dielectric elastomer actuator according to claim 1, The zwitterionic segment is formed from zwitterionic monomers.

9. The dielectric elastomer actuator according to claim 8, The zwitterionic monomer has a branched chain, the branched chain having an alkyl group and functional groups including sulfonate, carboxylate or phosphite.

10. The dielectric elastomer actuator according to claim 1, The potential difference mentioned therein is a voltage equal to or less than 800V.

11. A method for manufacturing a dielectric elastomer actuator, the method comprising: Fabricating a dielectric elastomer layer comprising a dielectric elastomer, the dielectric elastomer comprising zwitterionic segments and soft segments connected to the zwitterionic segments; Manufacturing the first electrode; Manufacturing the second electrode; and Provide one or more structural components; The dielectric elastomer actuator is configured such that, in response to a potential difference applied between the first electrode and the second electrode, a force is applied to the dielectric elastomer layer due to Maxwell stress, thereby moving the one or more structural members.

12. The method according to claim 11, The dielectric elastomer further includes one or more diisocyanate segments.

13. The method according to claim 12, The dielectric elastomer is manufactured by the following steps: The zwitterionic monomer, soft segment precursor and solvent are mixed to form a mixture; Heating the mixture at a first preset temperature; and After the mixture is cooled from the first preset temperature to the second preset temperature, one or more diisocyanate monomers and catalysts are applied to the mixture.

14. The method according to claim 13, The zwitterionic monomer is manufactured by the following steps: The first precursor, the second precursor, and another solvent are mixed to form a solution; and The solution is heated to form the zwitterionic monomer.

15. The method according to any one of claims 11 to 14, The dielectric elastomer layer is formed by depositing the dielectric elastomer using a suitable deposition process selected from blade coating, spin coating, dip coating, spray coating, screen printing, inkjet printing and 3D printing.

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