Robust Three‐Component Elastomer–Particle–Fiber Composites with Tunable Properties for Soft Robotics

Nasab, Amir Mohammadi; Sharifi, Siavash; Chen, Shuai; Jiao, Yang; Shan, Wanliang

doi:10.1002/aisy.202000166

Cited by 20 publications

(23 citation statements)

References 52 publications

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“…Another point worth mentioning is that we used LMPA channels for activation, which is convenient but not reliable as the circuitry might break during loading when LMPA is in the solid phase. While reheating and resolidifying of the LMPA channels can restore the circuitry, novel smart materials such as the three-component ones containing LMPA inclusions ( Mohammadi Nasab et al, 2020 ) will significantly improve the reliability of this approach to dynamically tunable friction. In addition, adopting these novel smart materials will also enable minimization and much quicker dynamic modulation of friction.…”

Section: Resultsmentioning

confidence: 99%

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Dynamically Tunable Friction via Subsurface Stiffness Modulation

et al. 2021

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Currently soft robots primarily rely on pneumatics and geometrical asymmetry to achieve locomotion, which limits their working range, versatility, and other untethered functionalities. In this paper, we introduce a novel approach to achieve locomotion for soft robots through dynamically tunable friction to address these challenges, which is achieved by subsurface stiffness modulation (SSM) of a stimuli-responsive component within composite structures. To demonstrate this, we design and fabricate an elastomeric pad made of polydimethylsiloxane (PDMS), which is embedded with a spiral channel filled with a low melting point alloy (LMPA). Once the LMPA strip is melted upon Joule heating, the compliance of the composite structure increases and the friction between the composite surface and the opposing surface increases. A series of experiments and finite element analysis (FEA) have been performed to characterize the frictional behavior of these composite pads and elucidate the underlying physics dominating the tunable friction. We also demonstrate that when these composite structures are properly integrated into soft crawling robots inspired by inchworms and earthworms, the differences in friction of the two ends of these robots through SSM can potentially be used to generate translational locomotion for untethered crawling robots.

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Section: Resultsmentioning

confidence: 99%

“…The material properties of the composite pad sample that are used in the FEA simulation(Mohammadi Nasab et al, 2020).…”

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confidence: 99%

Dynamically Tunable Friction via Subsurface Stiffness Modulation

et al. 2021

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“…[24] Among phase change materials, low melting point alloy (LMPA) has been used extensively as they exhibit a wide range of stiffness spans (≈10 0 -10 10 Pa). [25] This material with programmable stiffness enables the multifunctional machines with simple designs, and their tunable stiffness properties contribute to accomplishing varying real-time tasks. [26] For instance, Wang et al presented a flexible manipulator that exploited the phase transformation property of LMPA to regulate the structural stiffness by heating or cooling.…”

Section: Introductionmentioning

confidence: 99%

Bioinspired Continuum Robots with Programmable Stiffness by Harnessing Phase Change Materials

Zhang¹,

Wang²,

Chen³

et al. 2023

Adv Materials Technologies

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are referred to as continuum robots. [1] Compared with traditional robots composed of rigid links and joints, continuum robots featured with both softness and compliance exhibit reduced complexity in interactions with the environment in application scenarios, such as minimally invasive surgery, [2] environment exploration, [3] and safe human-robot interaction. [4] As a promising candidate for constructing safe human-centered robots, continuum robots are shifting the mechanical design of intelligent machines from the sole use of rigid materials toward the use of compliant materials. [5] However, these robots are challenged by the inherent contradiction between softness and load-bearing capacity when dealing with stress application scenarios, since the carrying capacity of compliant materials is much worse than that of rigid materials. [6] Aiming at this inherent challenge in existing continuum robots, a hybrid robotic system that combines both soft and rigid materials may figure out the contradiction between the structural stiffness and shape adaption capability. [7] Tensegrity structures, created by Fuller, may provide a novel paradigm for the continuum robotic design. [8] The combination of rigid components and high softness endows this structure with desirable characteristics found in both classically rigid and Continuum robots offer significant advantages over traditional ones in some specific scenarios, such as urban search and rescue, minimally invasive surgery, and inspection of cluttered environments. However, motions and/or operations of existing continuum robots always suffer from those limitations in varying curvature interaction scenarios because of the homogeneity and singleness of the structural stiffness. Herein, inspired by the mechanism of an elephant trunk for regulating local stiffness, a three-segment continuum robot constructed by tensegrity structure, which relies on a stiffness tunable material, with its Young's modulus switchable between 1.79 and 271.62 MPa to achieve the robotic stiffness programmable characteristics, is proposed. For predicting the robotic configuration with varying stiffness distribution, a mechanical model based on the framework of the finite element method is derived. Theoretical predictions reveal that the curvature of each segment can be regulated by programming stiffness of the smart materials; therefore, the customizable design can offer an effective route for real-time robotic interactions. By evaluating motion characteristics, stiffness performance, and conformal interaction capability, the experimental results demonstrate that the robot can freely regulate the configuration on-demand, which may provide a foundation for the application of continuum robots with programmable stiffness for interacting with unstructured environments.

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“…A variety of methods have been employed to attain variable stiffness, 15 including pneumatic jamming, 16,17 magnetorheological and electrorheological materials, 18–21 shape memory polymers and alloys, 22–25 liquid crystal elastomers, 26–28 and phase-changing materials. 29–33 Typically derived from metallic alloys, waxes, or thermoplastic polymers, encapsulated phase-changing materials exhibit a decrease in modulus via the transition from solid to liquid, and raise in modulus via the reverse (solidification) transition. One phase-changing material gaining traction in the literature is Field's metal, a eutectic alloy of bismuth, indium, and tin known for its low melting point of T m = 62 °C and non-hazardous composition.…”

Section: Introductionmentioning

confidence: 99%