Untethered soft robotic matter with passive control of shape morphing and propulsion

Kotikian, Arda; McMahan, Connor; Davidson, Emily C.; Muhammad, Jalilah M.; Weeks, Robert D.; Daraio, Chiara; Lewis, Jennifer A.

doi:10.1126/scirobotics.aax7044

Cited by 336 publications

(338 citation statements)

References 61 publications

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“…Complex 3D flexible structures that incorporate active and functional materials are of growing interest for many emerging systems, such as biosensing, energy harvesting, and mechanobiology. [ 40–42 ] Here, the robust thin‐film SLiR integrating sensors and actuators when combined with the kirigami technique provides new opportunities for advanced soft robotics. Figure a presents examples of programmed 3D architectures transforming from the corresponding 2D precursors triggered by light, including saddles, nested cage, closed‐loop S‐shape and star‐shape dome.…”

Section: Figurementioning

confidence: 99%

Somatosensory, Light‐Driven, Thin‐Film Robots Capable of Integrated Perception and Motility

et al. 2020

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to physical cues. [4,5] Mimicking such intelligent responses in artificial systems is a long-standing challenge that requires the integration of stimulus-responsive motility and perception feedback in a robotic body. [6] To date, the mainstream efforts on robot intelligence have been made in programmable control of rigid bodies that rely on individual computational modeling and electric actuation to achieve specific prescribed robot actions, [7] while the complex computing systems, power sources, and electrical motors restrict the robot body from size miniaturization and high-level of motion adaptivity. The realization of intelligent response in a miniature robot requires new design strategies capable of providing tightly coupled actuation and sensing mechanisms, and body compliance.Soft robotics is an emerging field that strives to bridge the gap between robots and biological living organisms. [8] Unlike conventional hard machines, soft robots are comprised of structures that continuously response, deform and morph in efforts to autonomously adapt to surroundings, manipulate objects, and execute dexterous maneuvers. [9] Without doubt, the stimulus responsiveness and multifunctionalities of active soft matter have opened up opportunities for diverse designs of actuation strategies [10][11][12][13][14][15] (including light, heat, humidity, electrical, pneumatic, and magnetic actuation) and sensing schemes [16][17][18][19][20] (such as resistive, capacitive, and self-powered sensing). Synchronous motility and multisensory perception in one compact system, especially when the robot size is down to centimeter scale, still proves a particular fabrication challenge. [21] So far, limited embodiments based on a single mode of sensory feedback mechanism have been achieved, [22][23][24][25][26][27][28][29] such as ionic capacitive sensors embedded in a pneumatic actuator, [23] liquid metal strain sensors integrated in a soft gripper, [30] and piezoresistive strain feedback in artificial muscles. [26] And few attempts at integrating multifunctional sensing schemes [31,32] have revealed inherent limitations in multiple connection terminals, complex electric power inputs, and complicated fabrication processes, where trade-offs between the actuation/shape adaptivity and sensing capability is unavoidable.Here, we overcome these challenges using an integral thinfilm construct to demonstrate fabrication of customizable, Living organisms are capable of sensing and responding to their environment through reflex-driven pathways. The grand challenge for mimicking such natural intelligence in miniature robots lies in achieving highly integrated body functionality, actuation, and sensing mechanisms. Here, somatosensory light-driven robots (SLiRs) based on a smart thin-film composite tightly integrating actuation and multisensing are presented. The SLiR subsumes pyro/piezoelectric responses and piezoresistive strain sensation under a photoactuator transducer, enabling simultaneous yet non-interfering perception of its body temperature a...

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Section: Figurementioning

confidence: 99%

Somatosensory, Light‐Driven, Thin‐Film Robots Capable of Integrated Perception and Motility

et al. 2020

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“…By contrast, 3D printing enables the rapid design and fabrication of soft materials in nearly arbitrary geometries . For example, direct ink writing (DIW), an extrusion‐based 3D printing method, has been used to pattern soft functional materials, including sensors, stretchable electronics, liquid crystalline elastomers, and soft robots . While this method has recently been used to print DEAs, they do not exhibit an in‐plane contractile response …”

Section: Introductionmentioning

confidence: 99%

3D Printing of Interdigitated Dielectric Elastomer Actuators

Chortos

Hajiesmaili

Morales

et al. 2019

Adv Funct Materials

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151

128

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Dielectric elastomer actuators (DEAs) are soft electromechanical devices that exhibit large energy densities and fast actuation rates. They are typically produced by planar methods and, thus, expand in-plane when actuated. Here, reported is a method for fabricating 3D interdigitated DEAs that exhibit in-plane contractile actuation modes. First, a conductive elastomer ink is created with the desired rheology needed for printing high-fidelity, interdigitated electrodes. Upon curing, the electrodes are then encapsulated in a self-healing dielectric matrix composed of a plasticized, chemically crosslinked polyurethane acrylate. 3D DEA devices are fabricated with tunable mechanical properties that exhibit breakdown fields of 25 V µm −1 and actuation strains of up to 9%. As exemplars, printed are prestrainfree rotational actuators and multi-voxel DEAs with orthogonal actuation directions in large-area, out-of-plane motifs.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adfm.201907375.cycling and breakdown behavior [33][34][35] and the presence of a rigid frame limits the geometries that can be achieved. [24,36] Recent attention has been directed toward developing approaches that enable contractile displacements in prestrain-free DEAs, including manual and automated stacking of individual planar layers [37] or sequential deposition of active materials via inkjet printing [38] and spray coating. [39] The fabrication of contractile actuators with vertically oriented electrodes offers a more promising approach (Figure 1b). While arrays of vertical electrodes can be patterned lithographically, new masks must be generated for each device design. [40][41][42] By contrast, 3D printing enables the rapid design and fabrication of soft materials in nearly arbitrary geometries. [43][44][45][46][47] For example, direct ink writing (DIW), an extrusion-based 3D printing method, has been used to pattern soft functional materials, including sensors, [48] stretchable electronics, [49] liquid crystalline elastomers, [50] and soft robots. [51,52] While this method has recently been used to print DEAs, they do not exhibit an in-plane contractile response. [52][53][54] Here, we create 3D DEAs composed of interdigitated vertical electrodes that are printed, cured, and encapsulated in an insulating dielectric matrix (Figure 1c). These prestrain-free contractile DEAs can be produced in nearly arbitrary geometries. During their actuation, the stress generated is given by σ = ε 0 ε r (E) 2 , where ε 0 is the vacuum permittivity, ε r is the dielectric constant, and E is the electric field. For small strains, the actuation strain (s z ) is s z = σ/E Y = ε 0 ε r (E) 2 /E Y , where E Y is the Young's modulus. Their actuation performance is therefore maximized by increasing the breakdown field and dielectric constant, while simultaneously reducing the elastic modulus of the matrix. Since variations in the dielectric thickness can cause localization of the electric field that results in p...

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“…Creating robotic elements, like a microscopic hand, that respond automatically to objects of certain spectral properties (color) is an example of such behavior. The sensitivity of polymers to their environment can also be used to create robots that move based on chemical gradients, thermal gradients,81 differences in pH, or the presence of other robots. One can envision the future realization of microscopic robots that perform simple tasks without human intervention or self‐assemble into more complex objects.…”

Section: Pros and Cons Discussionmentioning

confidence: 99%

Pros and Cons: Magnetic versus Optical Microrobots

2020

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Mobile microrobotics has emerged as a new robotics field within the last decade to create untethered tiny robots that can access and operate in unprecedented, dangerous, or hard‐to‐reach small spaces noninvasively toward disruptive medical, biotechnology, desktop manufacturing, environmental remediation, and other potential applications. Magnetic and optical actuation methods are the most widely used actuation methods in mobile microrobotics currently, in addition to acoustic and biological (cell‐driven) actuation approaches. The pros and cons of these actuation methods are reported here, depending on the given context. They can both enable long‐range, fast, and precise actuation of single or a large number of microrobots in diverse environments. Magnetic actuation has unique potential for medical applications of microrobots inside nontransparent tissues at high penetration depths, while optical actuation is suitable for more biotechnology, lab‐/organ‐on‐a‐chip, and desktop manufacturing types of applications with much less surface penetration depth requirements or with transparent environments. Combining both methods in new robot designs can have a strong potential of combining the pros of both methods. There is still much progress needed in both actuation methods to realize the potential disruptive applications of mobile microrobots in real‐world conditions.

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Untethered soft robotic matter with passive control of shape morphing and propulsion

Cited by 336 publications

References 61 publications

Somatosensory, Light‐Driven, Thin‐Film Robots Capable of Integrated Perception and Motility

Somatosensory, Light‐Driven, Thin‐Film Robots Capable of Integrated Perception and Motility

3D Printing of Interdigitated Dielectric Elastomer Actuators

Pros and Cons: Magnetic versus Optical Microrobots

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