In-plane shaking of nanoresonators throws off impurities.

A cool new technology for detection of bacteria, viruses, DNA and other biological molecules has been demonstrated. Resonators (cantilevers) made of narrow strips of silicon a few millionths of a meter long with bound antibodies can be used to detect bacteria suspended in a sample. The bacteria specifically attach to the antibodies and so alter the vibration in a detectable way. The problem is when other impurities in the sample attach non-specifically to the cantilever.

The new paper shows that non-specifically bound material can be shaken off if the resonator vibrates 'in plane', i.e.,side to side. In-plane vibration can be created by hitting the base of the cantilever with a laser beam pulsing at a certain frequency. To measure in-plane motion the researchers shined another laser on the free end of the cantilever and detected the chopping of the beam as the cantilever moved.

So the new technology could work like this: the cantilever is first vibrated up and down to let the sample components attach to it. Then it is made to vibrate sideways to shake of things that didn't attach specifically. What is left are those components you're trying to detect (if they are there) and so you can reliable measure their presence.

Imagine in the future going to a doctor who takes a sample and sends it to the lab. Instead of waiting hours or days to find out if there is an infection and if so what's causing it, the wait could potentially be reduced to minutes. There is a lot work needed to get to that, but we're on our way! Very neat stuff.