An embedded interface regulates the underwater actuation of solvent-responsive soft grippers

Meena, Rajesh Kumar; Rapaka, S Chandra Bose; Pratoori, Raghunandan; Annabattula, Ratna Kumar; Ghosh, Pijush

doi:10.1039/d1sm01229k

Cited by 11 publications

(8 citation statements)

References 27 publications

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“…The tendency of the film to bend in a specific direction is determined by the rate of concentration change at a particular time. 65 ̆̆, the film does not experience any bending and remains as it is. It is observed in Figure 9b that the relative rate of concentration change is highest in the bottom layer, followed by the middle and top layer during the initial time of folding (up to ∼12 s).…”

Section: Case I: Actuation Under Immersed Environmentmentioning

confidence: 98%

Solvent-Responsive Functionally Graded Hydrogel Thin Films for Programmed Actuation

Debta,

Kumbhar,

Ghosh

et al. 2024

ACS Appl. Eng. Mater.

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Shape-shifting solvent-responsive hydrogels have emerged as a crucial material platform for the design of soft robots, sensors, and actuators. Generally, to achieve actuation under different environments, using a layered structure with heterogeneous properties is a prevalent approach. However, the nonuniform force distribution at the interface between the layers can induce material delamination, thus greatly compromising the system’s stability and applicability. Here, we present the fabrication, design, and analysis of a reversible and structurally stable single-component functionally graded (FG) hydrogel thin film. The gradation is in terms of the modulus and diffusion coefficient. The FG film exhibits a fast actuation rate and is capable of actuating in both immersed and nonimmersed aqueous environments. The fabricated FG film can eliminate the requirement for a layered structure yet retain all its functionalities. A coupled diffusion–deformation framework using the finite element (FE) method is employed to comprehend the mechanism and understand the factors governing the actuation of a FG film. The displacement profiles obtained from the simulations are successfully compared with the experiments for a FG–chitosan–water system. The rate of concentration change in different layers of the FG film is shown to play a pivotal role in steering the direction of actuation as well as the reversibility of folding under different conditions. The differential strain obtained from the length change between the different layers of the FG films is identified as a contributing factor for different actuation rates. Additionally, the simulation curvatures from different scenarios elucidate the influence of cross-linking gradation, water diffusion, and thickness on the folding of a FG film. As a prospective application, we demonstrate the design of different underwater grippers using geometrically engineered symmetric and asymmetric FG films.

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Section: Case I: Actuation Under Immersed Environmentmentioning

confidence: 98%

Solvent-Responsive Functionally Graded Hydrogel Thin Films for Programmed Actuation

Debta,

Kumbhar,

Ghosh

et al. 2024

ACS Appl. Eng. Mater.

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“…Furthermore, the unit cell and the passive layer are assumed to be made of the same material. A concern when it comes to bonding of layers with differing thermal coefficients is the separation of the layers, however, recent studies [73][74][75] have shown that strong interface adhesion can be achieved through appropriate interface engineering. The geometric and material properties of the proposed unit cell are as defined in table 1.…”

Section: Validation Of the Analytical Modelmentioning

confidence: 99%

“…The external stimulus is applied as a temperature field to the model in order to induce an eigenstrain. The materials and stimuli have been chosen such that the effective response mimics the behavior of the film proposed in Meena et al [73]. Boundary conditions are applied, constraining the left surface of the unit cell in the X direction and a point on the surface in the Y and Z directions to prevent rigid body motions.…”

Section: Validation Of the Analytical Modelmentioning

confidence: 99%

Design of auxetic cellular structures for in-plane response through out-of-plane actuation of stimuli-responsive bridge films

Chandramouli,

Rapaka,

Annabattula

2024

Smart Mater. Struct.

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In this work, we propose novel designs of cellular structures exhibiting unconventional in-plane actuation responses to external stimuli. We strategically introduce stimuli-responsive bilayer bridge films within conventional honeycombs to achieve the desired actuation. The films are incorporated such that, in response to an external field (thermal, electric, chemical, etc.), the bridge film bends out-of-plane, activating the honeycomb in the plane. The conventional out-of-plane deformation of the bridge film can lead to interesting and unconventional actuation in the plane. An analytical model of this coupled unit cell behaviour is developed using curved beam theory, and the model is validated against finite element simulations. Several applications of such designs are presented. Unit cell architectures exhibiting both positive and negative macroscopic actuation are proposed, and the criterion for achieving such actuation is derived analytically. Furthermore, we demonstrate that by altering the topology, unidirectional and bidirectional negative actuation can be achieved. We also propose designs that result in the negative actuation of the structure with both monotonically increasing and monotonically decreasing stimuli. Finally, by combining two macroscopic structures with positive and negative actuation, we design actuators/sensors that bend in the plane in response to a stimulus.

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“…Motions previously achieved using motors and mechanical actuators are replaced by smart actuators that respond to specific stimuli 6–9 . Stimuli‐responsive actuators like light/heat‐responsive liquid crystal polymers, solvent/vapor‐responsive hydrogels and heat‐responsive shape memory alloys were recently developed 4,5,10–25 . Inspired by nature, researchers have developed actuators that can perform complex actions using these responsive systems.…”

Section: Introductionmentioning

confidence: 99%

“…[6][7][8][9] Stimuli-responsive actuators like light/heatresponsive liquid crystal polymers, solvent/vapor-responsive hydrogels and heat-responsive shape memory alloys were recently developed. 4,5,[10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] Inspired by nature, researchers have developed actuators that can perform complex actions using these responsive systems. Actuators which mimick the blooming of flowers, [26][27][28][29][30] motion of caterpillars, [31][32][33] trapping of flies like Venus flytrap 6 and tight rolling of proboscis of butterfly, 34,35 among others, were developed.…”

Section: Introductionmentioning

confidence: 99%

Calla Lily flower inspired morphing of flat films to conical tubes

Peeketi

Sol

Swaminathan

et al. 2022

Journal of Polymer Science

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Recently researchers have developed soft actuators capable of morphing into complex shapes taking inspiration from nature. In this paper, we have developed a splay-nematic liquid crystal polymer network tapered actuator that can morph from a flat film to a cone, mimicking the blooming of single petal Calla Lily flower. We have demonstrated the formation of conical tubes through finite element simulations and experiments. The influence of tapering and alignment orientations with respect to the edge of the film on the cones is analyzed through simulations. The design with tapering and splayed alignments oriented at 45 to the edge is found to be the optimal choice for forming conical tubes.

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An embedded interface regulates the underwater actuation of solvent-responsive soft grippers

Abstract: In this work, we report the role of an embedded interface between two polymer thin films in determining the overall folding and actuation characteristics of a bilayer system applied for...

Cited by 11 publications

References 27 publications

Solvent-Responsive Functionally Graded Hydrogel Thin Films for Programmed Actuation

Solvent-Responsive Functionally Graded Hydrogel Thin Films for Programmed Actuation

Design of auxetic cellular structures for in-plane response through out-of-plane actuation of stimuli-responsive bridge films

Calla Lily flower inspired morphing of flat films to conical tubes

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