SciTech

NanoRobotics Lab models robots after nature

Dry fibrillar adhesives allow gecko-like robots to climb smooth, vertical surfaces. The NanoRobotics Lab created a synthetic version of the gecko’s toes, consisting of microscopic fibers with special tips that allow them to stick to surfaces. (credit: Courtesy of Wikimedia Commons) Dry fibrillar adhesives allow gecko-like robots to climb smooth, vertical surfaces. The NanoRobotics Lab created a synthetic version of the gecko’s toes, consisting of microscopic fibers with special tips that allow them to stick to surfaces. (credit: Courtesy of Wikimedia Commons)

When it comes to design, nothing beats the elegance of nature. Nature is the ultimate paradox of simplicity and complexity — every feature is designed for its function, yet most are impossible to recreate without highly advanced technology. Undeterred, the NanoRobotics Lab aspires to re-create nature in the form of robots.

Led by associate professor Metin Sitti, the lab is part of the mechanical engineering department at Carnegie Mellon. It consists of a group of students working on a variety of robots that have been inspired by nature. Casey Kute, a Ph.D. student in mechanical engineering and a member of the NanoRobotics Lab, described the various projects the students are currently working on. “Projects range from particle manipulation with an atomic force microscope to magnetic micro-robots to a small hummingbird-inspired flier to palm-sized wall-climbing robots,” she said.

A robot created by the NanoRobotics Lab was designed to climb walls like a gecko, a small lizard able to climb vertical surfaces with ease. According to a Carnegie Mellon press release, an exhibit was held at the Museum of Science in Boston showcasing this robot. The innovation that allows the robot to climb a smooth, vertical wall is called dry fibrillar adhesives. “The gecko’s trick to sticking to surfaces lies in its feet, specifically the very fine hairs on its toes,” Kute said. “There are billions of these tiny hairs, which make contact with the surface and create a huge collective surface area of contact.”

Using this as a reference, the NanoRobotics Lab created a synthetic version of the gecko’s toes consisting of microscopic fibers with special tips that allow them to stick to surfaces. “The dry adhesion force comes from surface contact forces such as van der Waals forces, which act between all materials in contact,” said Kute. The Van der Waals forces, in this case, are attractive forces between molecules that come near to each other, allowing them to bond, or “stick,” to each other.

While the technology imitates a gecko’s physiology, the robot itself looks like a small box with circuitry and large wires extending from it, as recorded on a video available from the Museum of Science in Boston website.
The box moves by rotating two cross-shaped objects connected to either side of it. Each of these crosses resembles a wheel with four thick spokes, without a circular rim around it. The ends of the spokes have the adhesive material attached. By rotating the crosses, the adhesive can selectively stick to walls, allowing for mobility. “Our robots use the principles used by geckos, but do not look like the lizard,” Kute said.

The team realizes it is better to not completely imitate nature, which has limitations. Rather, they base their robots on natural principles, but develop them further. “Nature evolves designs that are ‘good enough,’ which is to say they function well, but are not fully optimized. By looking to nature for inspiration, we can start with a partially optimized model. It allows us to move more quickly to a fully optimized model,” Kute explained.

While these robots are a technical achievement, current technological limitations still exist, preventing their practical use. Energy is an area of technology that is still surpassed by nature. “One main technical limitation is power. Animals in nature are able to metabolize their energy from their surroundings,” Kute said. “A robot has to either carry all of its power with it or be tethered, which limits its possible coverage area.” Another limitation is repair. Animals heal without the slightest thought as to what their body is doing, but re-creating the healing process in robots is difficult. “Animals are able to self-repair and adapt to their surroundings. obots are not yet widely able to do this,” Kute stated.

The robots offer practical purposes, as climbing robots can access rocky terrain more easily than those with wheels. The team already has applications of these robots in mind. “By having small robots that are able to cover diverse, complex environments, we hope that they will prove useful as knowledge sources for hazardous environments or places that are too small for humans to go. We anticipate our robots could help with pipe inspection, security monitoring, and medical applications,” Kute said.