Fast, cheap nanomanufacturing

Arrays of tiny conical tips that eject ionized materials could fabricate nanoscale devices cheaply

Luis Fernando Velásquez-García’s group at MIT’s Microsystems Technology Laboratories (MTL) develops dense arrays of microscopic cones that harness electrostatic forces to eject streams of ions.

The technology has a range of promising applications: depositing or etching features onto nanoscale mechanical devices; spinning out nanofibers for use in water filters, body armor, and “smart” textiles; or propulsion systems for fist-sized “nanosatellites.”

In the latest issue of the IEEE Journal of Microelectromechanical Systems, Velásquez-García, his graduate students Eric Heubel and Philip Ponce de Leon, and Frances Hill, a postdoc in his group, describe a new prototype array that generates 10 times the ion current per emitter that previous arrays did.

Ion current is a measure of the charge carried by moving ions, which translates directly to the rate at which particles can be ejected. Higher currents thus promise more-efficient manufacturing and more-nimble satellites.

The same prototype also crams 1,900 emitters onto a chip that’s only a centimeter square, quadrupling the array size and emitter density of even the best of its predecessors.

“This is a field that benefits from miniaturizing the components, because scaling down emitters implies less power consumption, less bias voltage to operate them, and higher throughput,” says Velásquez-García, a principal research scientist at MTL. “The topic we have been tackling is how we can make these devices operate as close as we can to the theoretical limit and how we can greatly increase the throughput by virtue of multiplexing, with massively parallel devices that operate uniformly.”

Nanoprinting

“In my opinion, the best nanosystems are going to be done by 3-D printing because it would bypass the problems of standard microfabrication,” Velásquez-García says. “It uses prohibitively expensive equipment, which requires a high level of training to operate, and everything is defined in planes. In many applications you want the three-dimensionality: 3-D printing is going to make a big difference in the kinds of systems we can put together and the optimization that we can do.”

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