The microscope is the new drill

Photo by Lori Lennon.

How many things can you do with a micro­scope? Before this morning I would have prob­ably said “one: mag­nify stuff.” Now I can con­fi­dently say “two: mag­nify and drill holes in stuff.”

Meni Wanunu, assis­tant pro­fessor of physics and chemistry/​chemical biology, will be using the university’s new trans­mis­sion elec­tron micro­scope (TEM) to make nanopores nucleic acid analysis and DNA sequencing.

TEM dif­fers from a stan­dard light-​​microscope in that it uses a beam of elec­trons as the “illu­mi­na­tion” source instead of a beam of pho­tons. A series of elec­tro­mag­nets work to focus the elec­tron beam before and after punc­turing the mate­rial. For imaging the mate­rial, the beam needs to be rel­a­tively dif­fuse, said Wanunu. Oth­er­wise it would destroy the sample.

Wanunu’s work in nanopores takes advan­tage of that exact draw­back. Instead of using a dif­fuse elec­tron beam, he focuses the beam down to a couple of nanome­ters. At this scale, the beam is incred­ibly pre­cise and pow­erful and can drill a clean, exacting hole into a mem­brane. Some mate­rials Wanunu has already drilled include sil­icon nitride and single-​​layer graphene membranes.

The orig­inal nanopore tech­nique used ion beams instead of elec­trons, but using elec­trons rather than ions offers much improved pre­ci­sion and less sample contamination.

While the instru­ment was pur­chased to enable Wanunu’s work, it will also be avail­able for other researchers inter­ested in drilling tiny holes or mag­ni­fying things. It is capable of making things only a couple Angstroms wide vis­ible to the naked eye. That’s the size of a single atom.

But doing so requires a lot of power. The elec­tron beam alone comes from a huge 200K volt battery!