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Swarms of Vibration-Controlled Microbots Could Be the Future of Surgery

The Daily Beast logo The Daily Beast 8/12/2019 By David Axe
Photo Illustration by The Daily Beast/Getty © Provided by The Daily Beast Photo Illustration by The Daily Beast/Getty

It’s a few years in the future. You’ve had an accident and suffered a nasty injury. You need surgery to repair the underlying tissue and close the wound. Back in 2019, a surgeon might have used stitches, staples, and glue to patch you up.

Not anymore. With a whistle, a surgeon commands a swarm of tiny robots to spread across your injured body part. Another, higher-pitched whistle, and the nearly too-small-to-see bots get to work suturing your wound. 

This surgical scenario is just one possible future if a new research project at the Georgia Institute of Technology works out. A team led by Azadeh Ansari, an assistant professor in the School of Electrical and Computer Engineering, is developing tiny, free-roaming robots that respond to vibrations. 

Yes, potentially even whistles. 

Control via vibration eliminates the need for tiny cables or any other direct, physical connection between the bot and the operator while also simplifying the device’s design. “We are interested in fabricating micro-robots that are robust and untethered in exploring their environment,” Ansari told The Daily Beast. 

Right now, Ansari’s bots are around two millimeters in length, roughly the size of small ants. While other researchers are working on vibration-controlled drones, Ansari’s apparently are the smallest, according to Science Daily. 

Ansari and her team have been experimenting with the bots in what they describe as a “playground”—in essence an obstacle course where they can maneuver, Science Daily reported.

Ansari aims to make the tiny drones even tinier while also making them more precise and easier to control. Surgery could be on the horizon. “Once the bots are further miniaturized, they can be sent into a human body,” she explained.

There also are industrial applications, Ansari added. “For example, sending them inside pipes or unaccessible locations or other harsh environments, where humans or larger bots cannot go.” 

Ansari 3D-prints her tiny micro-bots with lead zirconate titanate, a so-called “piezoelectric” material that generates voltage when it vibrates from, say, a sound wave passing through it. The voltage can power the nearly-microscopic components of a nearly-microscopic robot. Delicate legs. needle-tip-size sensors. Minuscule claws.

The piezoelectric material solves a problem of scale. “True micro-scale robots are too small to have on-board power for actuators, sensors and CPUs for on-board intelligent control,” David Cappelleri, a professor of mechanical engineering at Purdue University, told The Daily Beast.

But with components that respond to vibration, you don’t need on-board power. 

Piezoelectrics also could allow an operator to issue a variety of commands. “The bot reacts differently to various frequencies,” Ansari said. “For example, a six kilohertz wave would cause forward motion while a seven kilohertz frequency can cause a turn to the right or left.”

“Basically, the bots are steered with frequency and volume of sound waves,” she continued. “Thus, precisely controllable for real-time applications.”

Moreover, control-via-vibration could allow an operator to issue specific commands to a few bots, or even just one, in a swarm of potentially thousands of them. That’s because you can build each machine in the swarm to respond to a particular frequency or set of frequencies. 

That could solve one of the more vexing problems in the field of microbotics. Using, say, a magnetic field to guide a swarm of tiny metal bots tends to steer all of them in the same direction at the same time. “These fields are generally global fields,” Cappelleri explained.

While a whistle in theory could control a swarm of Ansari’s bots, it might need to be computer-generated in order to be precise enough to activate the sensitive little machines. For the same reason, don’t count on the tiny robots to respond to a human voice.

“Typical human voice is made of many harmonics and consists of various frequencies,” Ansari told The Daily Beast. “It is not a pure tone.”

Friction poses one of the biggest challenges. “For robots at the micro-scale, their inertial forces are very small and instead their surface forces dominate their behavior,” Cappelleri told The Daily Beast. 

In other words, they tend to stick to whatever surface they’re on. They need a lot of oomph to get moving. “As the size shrinks, locomotion gets harder,” Ansari admitted.

Assuming Ansari can solve the problems that are unique to such tiny machines, her new vibration-controlled bots in theory could make surgery or industrial repairs faster, more precise and less damaging to the thing, or person, they’re fixing. 

In practice, however, the new tech is useless for most people if it’s too expensive to deploy on a large scale. 

But Ansari said she’s optimistic the bots won’t price themselves out of usefulness. “3D-printing techniques that are rather cheaper than our current technique are available that could be used for avoiding high costs,” Ansari told The Daily Beast. “The beauty of our design is in its simplicity and robustness.”

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