A new progress in the creation of nanoprobes

Artist's concept of a nanoprobe connecting to a neuron (Image courtesy Lieber Group, Harvard University. All rights reserved)
Artist’s concept of a nanoprobe connecting to a neuron (Image courtesy Lieber Group, Harvard University. All rights reserved)

An article published in the journal “Nature Nanotechnology” riporta the creation of arrays of nanoprobes small enough to be able to record the internal work of cardiac cells and primary neurons. A team of researchers from the Universities of Surrey and Harvard produced U-shaped nanowire field-effect transistor probes. The possibility of measuring intracellular signals offers new possibilities in the medical field but also technological developments related to human-machine interfaces.

Equipment used to map the electrical activity of cells such as those in the brain are becoming increasingly sophisticated but the problems of the size and the possible invasiveness of the operation remain. Progress has also been made in the connection between nerves and electronic equipment such as bionic limbs in order to be able to command them directly with the mind but we’re just at the beginning.

In many cases the ideal solution would be to have microscopic probes capable of providing better mapping and connections than any macroscopic equipment. Now a team of researchers from the University of Surrey’s Advanced Technology Institute (ATI) and Harvard University announced the production of that type of nanoprobes.

Charles Lieber, a pioneer of nanotechnology at Harvard, has been working on the creation of nanoprobes usable for practical applications for several years. There are a number of development possibilities such as a nanoelectronic finite-state machine or nanoFSM composed of hundreds of nanowire transistors described in an article published in January 2014 in the journal “Proceedings of the National Academy of Sciences”.

The problem was to produce the individual microscopic transistors, certainly not easy, having to deal with nanowires. Field-effect transistors (FETs), were invented almost a century ago and are widespread in the field of electronics but reducing them to a microscopic size is far from easy. Charles Lieber and his team experimented with different solutions regarding the nanowire curve, which was originally V-shaped, testing various U-shaped curves. It turned out that the optimal shape is with a narrow tip and a tiny transistor.

One of the big problems in these advanced research is in the transition from lab to mass production. This is one of the cases when the production of nanoprobes presented problems, to the point that in the commentary on the new announcement the production with the original technique was described as a mess of invisible spaghetti. The researchers perfected the production technique to obtain separate nanoprobes that produces hundreds of U-shaped nanowires in the same time that in the past they took to produce only a couple since they’re now well aligned and easy to control.

Yunlong Zhao of ATI, one of the authors of the study, explained that those nanoprobes can be powerful tools for measuring intracellular signals without damaging cells. Today there’s the patch clamp technique but it’s harmful to cells, in the near future it could be overcome by these nanoprobes.

The perspectives are interesting, it remains to be seen if the progress made is sufficient for practical applications outside lab. For Charles Lieber, the most intriguing ones concern human-machine interfaces. Again, the applications are all to be assessed but cyborgs could be closer to reality.

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