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Microbots controlled by 'mini force fields'

Microbots controlled by 'mini force fields'

Researchers are using a technology linked to mini force fields to independently manage individual microrobots operating within groups, an advance aimed at using the tiny machines in areas, including manufacturing and medicine.

Findings are detailed in a research paper appearing this month in the journal Micromachines. Until now, it was only possible to control groups of microbots to move generally in unison, said David Cappelleri, an assistant professor of mechanical engineering at Purdue University.

The reason we want independent movement of each robot is so they can do cooperative manipulation tasks, he said.

The team developed a system for controlling the robots with individual magnetic fields from an array of tiny planar coils.

The robots are too small to put batteries on them, so they can't have onboard power, Cappelleri said. You need to use an external way to power them. We use magnetic fields to generate forces on the robots. It's like using mini force fields.

The research is revealing precisely how to control the robots individually.

We need to know, if a robot is here and it needs to go there, how much force needs to be applied to the robot to get it from point A to point B Cappelleri said. Once you figure out what that force has to be, then we say, what kind of magnetic field strength do we need to generate that force

The microbots are magnetic disks that slide across a surface. While the versions studied are around 2 millimeters in diameter - about twice the size of a pinhead - researches aim to create microbots that are around 250 microns in diameter, or roughly the size of a dust mite.

The robots are moved using attractive or repulsive forces and by varying the strength of the electrical current in the coils.

Independently controlled microbots working in groups might be useful in building microelectromechanical systems, or MEMS, minuscule machines that could have numerous applications from medicine to homeland security.

Microbots equipped with probe-like force sensors might then be used to detect cancer cells in a biopsy.

The coils were made by printing a copper pattern with the same technology used to manufacture printed circuit boards. They can be scaled down from their current size of about 4 millimeters. A new process, however, was needed to create a microscale prototype, he said.

The research is ongoing. The team will attempt to use microscale prototypes to assemble components for MEMS devices. One potential obstacle is the effect of van der Waals forces between molecules that are present on the scale of microns but not on the macroscale of everyday life.

The forces might cause stiction between tiny components that affect their operation.

Postdoctoral research associates Sagar Chowdhury and Wuming Jing, and Cappelleri authored the paper.

Microbots controlled by 'mini force fields'