There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Untethered small-scale (from several millimetres down to a few micrometres in all dimensions) robots that can non-invasively access confined, enclosed spaces may enable applications in microfactories such as the construction of tissue scaffolds by robotic assembly, in bioengineering such as single-cell manipulation and biosensing, and in healthcare such as targeted drug delivery and minimally invasive surgery. Existing small-scale robots, however, have very limited mobility because they are unable to negotiate obstacles and changes in texture or material in unstructured environments. Of these small-scale robots, soft robots have greater potential to realize high mobility via multimodal locomotion, because such machines have higher degrees of freedom than their rigid counterparts. Here we demonstrate magneto-elastic soft millimetre-scale robots that can swim inside and on the surface of liquids, climb liquid menisci, roll and walk on solid surfaces, jump over obstacles, and crawl within narrow tunnels. These robots can transit reversibly between different liquid and solid terrains, as well as switch between locomotive modes. They can additionally execute pick-and-place and cargo-release tasks. We also present theoretical models to explain how the robots move. Like the large-scale robots that can be used to study locomotion, these soft small-scale robots could be used to study soft-bodied locomotion produced by small organisms.

Small-scale soft-bodied robot with multimodal locomotion

Medical Image Computing and Computer-Assisted Intervention

Bull. Chem. Soc. Jpn. への投稿のすすめ

This review comprises a detailed survey of ongoing methodologies for soft actuators, highlighting approaches suitable for nanometer- to centimeter-scale robotic applications. Soft robots present a special design challenge in that their actuation and sensing mechanisms are often highly integrated with the robot body and overall functionality. When less than a centimeter, they belong to an even more special subcategory of robots or devices, in that they often lack on-board power, sensing, computation, and control. Soft, active materials are particularly well suited for this task, with a wide range of stimulants and a number of impressive examples, demonstrating large deformations, high motion complexities, and varied multifunctionality. Recent research includes both the development of new materials and composites, as well as novel implementations leveraging the unique properties of soft materials.

Soft Actuators for Small-Scale Robotics.

Self-Walking Gel

The detection of cracks on concrete surfaces is the most important step during the inspection of concrete structures. Conventional crack detection methods are performed by experienced human inspectors who sketch crack patterns manually; however, such detection methods are expensive and subjective. Therefore, automated crack detection techniques that utilize image processing have been proposed. Although most the image-based approaches focus on the accuracy of crack detection, the computation time is also important for practical applications because the size of digital images has increased up to 10 megapixels. We introduce an efficient and high-speed crack detection method that employs percolation-based image processing. We propose termination- and skip-added procedures to reduce the computation time. The percolation process is terminated by calculating the circularity during the processing. Moreover, percolation processing can be skipped in subsequent pixels according to the circularity of neighboring pixels. The experimental result shows that the proposed approach efficiently reduces the computation cost.

Fast crack detection method for large-size concrete surface images using percolation-based image processing

Peristaltic Motion of Polymer Gels

Novel conveyer gels exhibiting autonomous peristaltic motion without external stimuli were prepared by copolymerizing temperature-responsive N-isopropylacrylamide (NIPAAm), ruthenium tris(2,2′-bipyridine) (Ru(bpy)3) as the catalyst for the Belousov−Zhabotinsky (BZ) reaction, and 2-acrylamido-2-methylpropanesulfonic acid (AMPS). When the gel was immersed in the catalyst-free BZ solution, the BZ reaction occurred in the gel and the chemical wave propagated followed by the peristaltic motion of the gel. In this study, we investigated the influence of the AMPS feed ratio on the network structure and the swelling−deswelling properties of the poly(NIPAAm-co-Ru(bpy)3-co-AMPS) gels. The gel had a microphase-separated structure when the AMPS feed ratio was less than 5 mol % due to the effect of the poor solvent in the polymerization process. On the other hand, when the AMPS feed ratio is more than 10 mol %, the gel is a homogeneous structure. The microphase-separated structure highly improved the swelling−deswelli...

Design of a mass transport surface utilizing peristaltic motion of a self-oscillating gel.

A novel self-oscillating gel actuator with gradient structure, which generates a pendulum motion by fixing one edge of the gel without external stimuli was achieved. The gel was synthesized by copolymerizing the ruthenium catalyst for the Belousov-Zhabotinsky reaction with N-isopropylacrylamide and 2-acrylamido- 2-methylpropane sulfonic acid. Furthermore, we clarified that the period and amplitude for the self-oscillating behavior of the gel actuator are controllable by changing the composition, temperature, and size of the gel. The maximum amplitude of the novel gel actuator is about a 100 times larger than that of the conventional self-oscillating gel system.

Shuji Hashimoto

Papers

Self-Walking Gel

Fast crack detection method for large-size concrete surface images using percolation-based image processing

Peristaltic Motion of Polymer Gels

Design of a mass transport surface utilizing peristaltic motion of a self-oscillating gel.

Control of the Dynamic Motion of a Gel Actuator Driven by the Belousov-Zhabotinsky Reaction