biomimetics (4)

As The Worm Turns...


Schematic diagram of the worm-inspired robot. Credit: Jin et al.

Topics: Applied Physics, Biomimetics, Instrumentation, Mechanical Engineering, Robotics

Bio-inspired robots, robotic systems that emulate the appearance, movements, and/or functions of specific biological systems, could help to tackle real-world problems more efficiently and reliably. Over the past two decades, roboticists have introduced a growing number of these robots, some of which draw inspiration from fruit flies, worms, and other small organisms.

Researchers at China University of Petroleum (East China) recently developed a worm-inspired robot with a body structure that is based on the oriental paper-folding art of origami. This robotic system, introduced in Bioinspiration & Biomimetics, is based on actuators that respond to magnetic forces, compressing and bending its body to replicate the movements of worms.

"Soft robotics is a promising field that our research group has been paying a lot of attention to," Jianlin Liu, one of the researchers who developed the robot, told Tech Xplore. "While reviewing the existing research literature in the field, we found that bionic robots, such as worm-inspired robots, were a topic worth exploring. We thus set out to fabricate a worm-like origami robot based on the existing literature. After designing and reviewing several different structures, we chose to focus on a specific knitting pattern for our robot."

A worm-inspired robot based on an origami structure and magnetic actuators, Ingrid Fadelli, Tech Xplore

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Balsa Chips...


Modified wood modulates electrical current: researchers at Linköping University and colleagues from the KTH Royal Institute of Technology have developed the world’s first electrical transistor made of wood. (Courtesy: Thor Balkhed)

Topics: Applied Physics, Biomimetics, Electrical Engineering, Materials Science, Research

Researchers in Sweden have built a transistor out of a plank of wood by incorporating electrically conducting polymers throughout the material to retain space for an ionically conductive electrolyte. The new technique makes it possible, in principle, to use wood as a template for numerous electronic components, though the Linköping University team acknowledges that wood-based devices cannot compete with traditional circuitry on speed or size.

Led by Isak Engquist of Linköping’s Laboratory for Organic Electronics, the researchers began by removing the lignin from a plank of balsa wood (chosen because it is grainless and evenly structured) using a NaClO2 chemical and heat treatment. Since lignin typically constitutes 25% of wood, removing it creates considerable scope for incorporating new materials into the structure that remains.

The researchers then placed the delignified wood in a water-based dispersion of an electrically conducting polymer called poly(3,4-ethylene-dioxythiophene)–polystyrene sulfonate, or PEDOT: PSS. Once this polymer diffuses into the wood, the previously insulating material becomes a conductor with an electrical conductivity of up to 69 Siemens per meter – a phenomenon the researchers attribute to the formation of PEDOT: PSS microstructures inside the 3D wooden “scaffold.”

Next, Engquist and colleagues constructed a transistor using one piece of this treated balsa wood as a channel and additional pieces on either side to form a double transistor gate. They also soaked the interface between the gates and channels in an ion-conducting gel. In this arrangement, known as an organic electrochemical transistor (OECT), applying a voltage to the gate(s) triggers an electrochemical reaction in the channel that makes the PEDOT molecules non-conducting and therefore switches the transistor off.

A transistor made from wood, Isabelle Dumé, Physics World

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Syncing Fireflies...

Some fireflies have a mystifying gift for flashing their abdomens in sync. New observations are overturning long-accepted explanations for how the synchronization occurs, at least for some species.

Topics: Biology, Biomimetics, Biotechnology, Computer Modeling, Mathematics

In Japanese folk traditions, they symbolize departing souls or silent, ardent love. Some Indigenous cultures in the Peruvian Andes view them as the eyes of ghosts. And across various Western cultures, fireflies, glow-worms, and other bioluminescent beetles have been linked to a dazzling and at times contradictory array of metaphoric associations: “childhood, crop, doom, elves, fear, habitat change, idyll, love, luck, mortality, prostitution, solstice, stars and fleetingness of words and cognition,” as one 2016 review noted.

Physicists revere fireflies for reasons that might seem every bit as mystical: Of the roughly 2,200 species scattered around the world, a handful has the documented ability to flash in synchrony. In Malaysia and Thailand, firefly-studded mangrove trees can blink on the beat as if strung up with Christmas lights; every summer in Appalachia, waves of eerie concordance ripple across fields and forests. The fireflies’ light shows lure mates and crowds of human sightseers, but they have also helped spark some of the most fundamental attempts to explain synchronization, the alchemy by which elaborate coordination emerges from even very simple individual parts.

Orit Peleg remembers when she first encountered the mystery of synchronous fireflies as an undergraduate studying physics and computer science. The fireflies were presented as an example of how simple systems achieve synchrony in Nonlinear Dynamics and Chaos, a textbook by the mathematician Steven Strogatz that her class was using. Peleg had never even seen a firefly, as they are uncommon in Israel, where she grew up.

“It’s just so beautiful that it somehow stuck in my head for many, many years,” she said. But by the time Peleg began her own lab, applying computational approaches to biology at the University of Colorado and at the Santa Fe Institute, she had learned that although fireflies had inspired a lot of math, quantitative data describing what the insects were actually doing was scant.

How Do Fireflies Flash in Sync? Studies Suggest a New Answer. Joshua Sokol, Quanta Magazine

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4D Beetles...


Beetling along: Under the influence of moisture, the color of the 3D-printed beetle changes from green to red, and back again to red. (Courtesy: Bart van Overbeeke)

Topics: 3D Printing, Additive Manufacturing, Biomimetics

Researchers in the Netherlands have produced models of a beetle that changes color and a scallop shell that opens and closes in response to changing humidity in the surrounding air. Inspired by iridescent structures in nature, Jeroen Sol and colleagues at the Eindhoven University of Technology showed that they could integrate a specialized liquid crystal into standard 3D-printing techniques, creating “4D printed” devices that react to their changing environments.

Over millions of years, many organisms have evolved micro-scale structures in their anatomies that allow them to change their vibrant iridescent colors in response to stimuli. Recently, researchers have developed inks that change color in the same way and have begun to experiment with incorporating them into 3D-printed structures.

This technology has been dubbed 4D printing, where the fourth dimension represents reversible, time-varying changes to the structures after printing. One widely used technique in 4D printing is to deposit ink directly onto 3D printed structures. This approach can accommodate many types of material, as well as a versatile range of printing temperatures, speeds, and path designs.

4D-printed material responds to environmental stimuli, Sam Jarman, Physics World

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