An insect-scale robot is capable of flying, swimming, impulsively taking off from the water surface, and landing.

Remoras of the ray-finned fish family Echeneidae have the remarkable ability to attach to diverse marine animals using a highly modified dorsal fin that forms an adhesive disc, which enables hitchhiking on fast-swimming hosts despite high magnitudes of fluid shear. We present the design of a biologically analogous, multimaterial biomimetic remora disc based on detailed morphological and kinematic investigations of the slender sharksucker (Echeneis naucrates). We used multimaterial three-dimensional printing techniques to fabricate the main disc structure whose stiffness spans three orders of magnitude. To incorporate structures that mimic the functionality of the remora lamellae, we fabricated carbon fiber spinules (270 μm base diameter) using laser machining techniques and attached them to soft actuator–controlled lamellae. Our biomimetic prototype can attach to different surfaces and generate considerable pull-off force—up to 340 times the weight of the disc prototype. The rigid spinules and soft material overlaying the lamellae engage with the surface when rotated, just like the discs of live remoras. The biomimetic kinematics result in significantly enhanced frictional forces across the disc on substrates of different roughness. Using our prototype, we have designed an underwater robot capable of strong adhesion and hitchhiking on a variety of surfaces (including smooth, rough, and compliant surfaces, as well as shark skin). Our results demonstrate that there is promise for the development of high-performance bioinspired robotic systems that may be used in a number of applications based on an understanding of the adhesive mechanisms used by remoras.

Several animal species demonstrate remarkable locomotive capabilities on land, on water, and under water. A hybrid terrestrial-aquatic robot with similar capabilities requires multimodal locomotive strategies that reconcile the constraints imposed by the different environments. Here we report the development of a 1.6 g quadrupedal microrobot that can walk on land, swim on water, and transition between the two. This robot utilizes a combination of surface tension and buoyancy to support its weight and generates differential drag using passive flaps to swim forward and turn. Electrowetting is used to break the water surface and transition into water by reducing the contact angle, and subsequently inducing spontaneous wetting. Finally, several design modifications help the robot overcome surface tension and climb a modest incline to transition back onto land. Our results show that microrobots can demonstrate unique locomotive capabilities by leveraging their small size, mesoscale fabrication methods, and surface effects.

Flying insects are remarkably agile and robust. As they fly through cluttered natural environments, they can demonstrate aggressive acrobatic maneuvers such as backflip, rapid escape, and in-flight collision recovery. Current state-of-the-art subgram microaerial-vehicles (MAVs) are predominately powered by rigid actuators such as piezoelectric ceramics, but they have low fracture strength (120 MPa) and failure strain (0.3%). Although these existing systems can achieve a high lift-to-weight ratio, they have not demonstrated insect-like maneuvers such as somersault or rapid collision recovery. In this article, we present a 665 mg aerial robot that is powered by novel dielectric elastomer actuators (DEA). The new DEA achieves high power density (1.2 kW/kg) and relatively high transduction efficiency (37%). We further incorporate this soft actuator into an aerial robot to demonstrate novel flight capabilities. This insect-scale aerial robot has a large lift-to-weight ratio (>2.2:1) and it achieves an ascending speed of 70 cm/s. In addition to demonstrating controlled hovering flight, it can recover from an in-flight collision and perform a somersault within 0.16 s. This work demonstrates that soft aerial robots can achieve insect-like flight capabilities absent in rigid-powered MAVs, thus showing the potential of a new class of hybrid soft-rigid robots.