Dartmouth computer science graduate student Igor Paprotny dons his surgical scrubs, latex gloves and safety goggles and steps boldly into a class-100 cleanroom.
It's just business as usual for Paprotny, a member of a team of Dartmouth researchers that have spent the past seven years working on the world's smallest mobile, untethered robot, a machine that is only one tenth the thickness of a single human hair.
The team, a collaboration between the engineering and computer science departments, recently created the microrobot, which is one to two orders of magnitude smaller than previous micro-robotic systems, researchers said. The robot is remarkable not only for its size but also because it is steerable and untethered, meaning that it does not need to be attached to a power supply.
The microrobot, a product of microelectromechanical systems, or MEMS, is powered and controlled by the grid of electrodes on which it walks. Since it is so small, it has to move in an unconventional fashion because normal forces do not work at such a small scale.
"It doesn't drive on wheels but crawls like a silicon inchworm, making tens of thousands of 10-nanometer steps every second," computer science professor and team leader Bruce Donald said. "It turns by putting a silicon 'foot' out and pivoting like a motorcyclist skidding around a tight turn."
The device could not have any wheels or joints because they do not work on such a small scale.
"Machines this small tend to stick to everything they touch, the way the sand sticks to your feet after a day at the beach," said Craig McGray, who earned his Ph.D. in computer science working on the project and did most of the research.
Potential applications for MEMS and the microrobot concept include repairing integrated circuits, exploring hazardous environments and biotechnology. The nearest foreseeable application is in information technology security, namely identity verification and information protection.
"Imagine that you have a secret that you want to distribute to many people, so that the secret cannot be known unless all the people want to share their part of it," McGray said. "There are certainly ways of probing an electronic system, so you might think of this as a jigsaw puzzle. In order to assemble this, you must not only have all the right pieces but also the sequence that they're assembled into to get the correct shape."
While McGray is no longer working on the microrobot project, Paprotny is continuing the IT security applications research for his Ph.D. and hopes to have the first prototype of the security application ready sometime this fall.
Paprotny said he envisions the technology as a way to verify identity, even in personal encounters.
"There are a group of people who want to figure out if they're all who they say they are, so they each have a little vial of these robots. They each spread some on a substrate and enter a PIN or something," Paprotny said. "If we're all who we say we are, the microrobots assemble into a key, or message that, say, gives you the code to activate a nuclear weapon."
The Department of Homeland Security's Office of Domestic Preparedness gave a grant to the team through Dartmouth's Institute for Security Technology Studies because of the potential security applications of their technology. Donald was not authorized to comment on the size of the grant.
The initial, basic fabrication of the microrobots is done by MEMSCAP, a company that specializes in MEMS manufacturing, while the post-processing -- removing the microrobots from their protective polysilicone glass capsules and making the most delicate, important modifications to the microrobots -- and testing are carried out at the Thayer School of Engineering and in some cases at the Dartmouth Medical School.
Thayer's facilities, such as the Nanomaterials Lab and the Microengineering Lab, make the post-processing and testing possible. The labs include high-tech equipment and facilities such as thermoevaporators, micromanipulators and a class-100 cleanroom, which maintains less than one hundred particles larger than 0.5 microns in each cubic foot of air space.
"Dartmouth has very nice facilities and a very nice working atmosphere," Paprotny said.
Paprotny said that Thayer's facilities were so extensive that all the fabrication could probably be carried out there, but that it was more efficient to outsource some of it to MEMSCAP.
The research team also included Dr. Ursula Gibson and Thomas W. Davis of the Electromagnetic Nanostructures Lab, Thayer School, and Dr. Charles Daghlian of Ripple Electron Microscopy Facility. Mike Sinclair, a hardware researcher at Microsoft, also coauthored a paper with McGray on the untethered powered system and helped advise on it.
