Bristol steers light-driven ‘micro-robots’ with optical tweezers

Bristol University has revealed some of its work on the development of light-driven ‘micro-robots’ that can autonomously investigate and manipulate the nano-scale environment in a microscope.

Bristol University - an optically trapped probe with specially shaped conical handles

This image shows a schematic of an optically trapped probe with specially shaped conical handles and a sharp tip for imaging surface features.

In theory, says the university, such devices could allow the investigation of delicate biological samples, such as cells, in new ways. They would provide a new route to high-resolution imaging.

Researchers including Dr David Phillips, Professor Mervyn Miles and Dr Stephen Simpson of Bristol’s School of Physics aim to control such micro-robots using ‘optical tweezers’. And it is this topic that features in a paper published in Nature Photonics. They investigate how optical tweezers can be used to manipulate nanofabricated structures to generate high-resolution images.

“This work paves the way towards the development of light-driven micro-robotics by providing a set of design rules for how complicated micro-structures will behave in light fields, and using them to design a new scanning probe imaging system that can operate inside an enclosed microfluidic chamber,” said Dr Phillips.

The university writes:

This is the basis of optical tweezing technology: by focusing a laser towards particles in a microscope, scientists can use the light to pick them up, hold them still in one place, or move them around. The Bristol team fabricated a set of needle-like microscopic particle ‘probes’, and used optical tweezers to pick them up and scan them along the side of a surface inside a microscope sample.

By monitoring changes in the position of the needle as it glided over nano-scale bumps in the surface with a high-speed video camera, they were able to build up an image of the surface that was impossible to see from the microscope image alone.

Image: Illustration by David Phillips.


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