Optical Tweezers at Long Range and High Pressure (Creativity @ Home)

Optical tweezers move microscopic objects around using nothing more than the gentle touch of light itself. For over 20 years scientists have used optical tweezers to explore the small forces in nature - to watch and measure the motion of individual cells, bacteria and biomotors on a piconewton/nanometre scale. One problem with tweezers is that they require very powerful lenses meaning that the optical trap is usually less than a millimetre from the lens itself. This short range of the optical tweezers limits their application and it is this limitation we seek to overcome.Jointly with some of our international collaborators we will build a portable technology demonstrator where the trapping point can be a few mm above a simple mirror and 10mm away from the lens. We have just shown that these mirror traps can be electronically enhanced to give similar performance to a traditional tweezers.Again with our collaborators we wish to illustrate how such a system can allow science that is beyond the range of traditional systems. For example we will show optical trapping within an ultra-high pressure cell, which typically have diamond windows too thick for traditional systems. We will trap at pressure up to 1GigaPascal exploring the strange changes in resulting viscosity and, for example, look at whether bacteria can still swim. We will use the increased optical access to measure optical forces from first principles - addressing the age old dilemma of how much force a light beam really produces.This project was identified through creativity @ home from across the extend group with a project plan that was similarly devised.

This project will build upon recent developments in optical tweezers, showing that their operating range can be massively increased by the inclusion of a simple mirror within the sample cell. We have worked closely with the co-originators exploring how servo control with a high speed SLM can give this new approach a similar performance to a traditional system. In producing a refined and portable system we wish to demonstrate the benefits of this approach to the tweezers community and further afield. Beyond the existing community, we wish to show how it can impact other areas - such as the study of fluid and colloidal systems at ultra high pressure - an area inaccessible to traditional approaches. From an academic perspective we will promote our system through our continued publication of highly regarded, highly cited papers and invited conference presentations. By performing our key experiments in partnership with our international collaborators, not only do with create the strongest possible team, but we maximise the exposure of our techniques and the science that they enable. Within our basic technology grant we have just reached agreement with a British SME to transfer our high-speed camera technology for multi particle tracking, targeted at the existing tweezers community. But the same SME already makes more complicated optical systems and we have had preliminary discussions as to how they might explore the potential market for this new approach. One attractive feature is that the new approach might overcome some of the existing difficulties with the complicated patent landscape around traditional holographic tweezers systems. Our demonstrator unit will be key to this possible future engagement, either with our existing link or elsewhere. In any event our motivation within the collaboration is not a maximisation of licensing or royalty revenue but instead simply to see the technology transferred to the commercial sector preferably creating opportunity for high-tech employment here within the UK. This is compatible with Glasgow University's easy access IP policy that places meaningful exploitation as its key criteria.