To boldly sense what no probes have sensed before...

As a child, the very idea that Colonel Chris Hadfield would grow up to be an astronaut could be summed up in one word: impossible.

I recently attended a talk by this former commander of the International Space Station and first Canadian to walk in space, which was fascinating, inspirational and familiar. He described with wonder and awe the joy of greeting, challenging and overcoming ‘the impossible’, capturing the very essence of how most scientists I know feel about their work.

 
 

I’ve had the pleasure of working with one such scientist at the University of Bristol, Dr Massimo Antognozzi. Equally excited by challenging the sense of what is impossible Massimo’s ‘final frontier’ is pushing to measure what was previously considered unmeasurable at the nanoscale through Atomic Force Microscopy.

Catching up over a coffee last week Massimo explained:

“Although a cantilever is an incredibly sensitive device, it still has to be rigid (i.e. insensitive) enough to horizontally extend out over a sample. In doing so cantilevers sacrifice their true sensing potential.”

Overturning thirty years of AFM thinking, Massimo wondered what if we didn’t make the sacrifice and didn’t horizontally extend our cantilevers?  Could we mount them vertically? How sensitive could we be, and what could we sense at the nanoscale that before was considered impossible?

What Massimo found was that by rotating the probe into a vertical orientation the fundamental limit to the forces that can be measured inherent in the standard horizontal AFM orientation could be lifted.

Massimo's bold new thinking challenged the very construction of the ‘standard’ AFM and has led to the development of a new detection system, capable of measuring very small lateral movements of the probe as it interacts with the sample.

 
 ©eLife Journal

©eLife Journal

 

I've been very proud to be part of that journey, developing ultra-soft probes for use in this vertical orientation, in instruments capable of detecting lateral or shear forces acting on the cantilever and with spring constants of less than 10 femtoNewtons.  That's 1000 times more sensitive than conventional AFM probes!  Massimo said:

“While theoretical models exist for some systems in this new low-force regime, many we will be observing for the first time.

Exploring this with innovative sensors and instrumentation is really exciting.”

With this powerful instrumentation, Massimo and his co-workers have been able to apply scanning probe techniques to a new range of low-force applications.  From observing the procession a single kinesin molecular motor along a microtubule to the mechanosensitive responses of adhesin proteins binding to bacteria.

 And for Massimo the mission is only just beginning:

“The next step is to push the technology even further and get into the sub-femtoNewton range!”

It is his boundless enthusiasm to go where no AFMer has gone before that reminded me of the Hadfield talk and that for the true scientist there is no final frontier, only the next unknown, the next impossible to overcome. So let’s keep setting the warp drive to ‘inquisitive’ and see where the technology can take us next…

What ‘impossibles’ have you overcome in your work?

If you are interested in purchasing some ultra-soft probes we can provide them here.