Matching the rich multimodality of natural organisms, i.e., the ability to transition between crawling and swimming, walking and jumping, etc., represents a grand challenge in the fields of soft and bioâinspired robotics. Here, a multimodal soft robot locomotion using highly compact and dynamic bistable soft actuators is achieved. These actuators are composed of a prestretched membrane sandwiched between two 3D printed frames with embedded shape memory alloy (SMA) coils. The actuator can swiftly transform between two oppositely curved states and generate a force of 0.3 N through a snapâthrough instability that is triggered after 0.2 s of electrical activation with an input power of 21.1 Âą 0.32
Shape-memory actuators allow machines ranging from robots to medical implants to hold their form without continuous power, a feature especially advantageous for situations where these devices are untethered and power is limited. Although previous work has demonstrated shape-memory actuators using polymers, alloys, and ceramics, the need for micrometer-scale electroâshape-memory actuators remains largely unmet, especially ones that can be driven by standard electronics (~1 volt). Here, we report on a new class of fast, high-curvature, low-voltage, reconfigurable, micrometer-scale shape-memory actuators. They function by the electrochemical oxidation/reduction of a platinum surface, creating a strain in the oxidized layer that causes bending. They bend to the smallest radius of curvature of any electrically controlled microactuator (~500 nanometers), are fast (<100-millisecond operation), and operate inside the electrochemical window of water, avoiding bubble generation associated with oxygen evolution. We demonstrate that these shape-memory actuators can be used to create basic electrically reconfigurable microscale robot elements including actuating surfaces, origami-based three-dimensional shapes, morphing metamaterials, and mechanical memory elements. Our shape-memory actuators have the potential to enable the realization of adaptive microscale structures, bio-implantable devices, and microscopic robots.
more » « less- Award ID(s):
- 1935252
- NSF-PAR ID:
- 10217797
- Publisher / Repository:
- American Association for the Advancement of Science (AAAS)
- Date Published:
- Journal Name:
- Science Robotics
- Volume:
- 6
- Issue:
- 52
- ISSN:
- 2470-9476
- Page Range / eLocation ID:
- Article No. eabe6663
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract W (i.e., electrical energy input of 4.22 Âą 0.06J . The consistency and robustness of the snapâthrough actuator response is experimentally validated through cyclical testing (580 cycles). The compact and fastâresponding properties of the soft bistable actuator allow it to be used as an artificial muscle for shapeâreconfigurable soft robots capable of multiple modes of SMAâpowered locomotion. This is demonstrated by creating three soft robots, including a reconfigurable amphibious robot that can walk on land and swim in water, a jumping robot (multimodal crawler) that can crawl and jump, and a caterpillarâinspired rolling robot that can crawl and roll. -
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