Changing the Way Microscopic Particles are Manipulated

The way cells and biomolecules are moved from one position to another could be transformed thanks to a grant of £4 million. The EPSRC 4-year grant has been awarded to a collaborative research team led by Bruce Drinkwater, Professor of Ultrasonics in the Department of Mechanical Engineering at the University of Bristol.

The project aims to create a new technological device called 'electronic sonotweezers' that will change the way microscopic particles are manipulated. The group plan to show how the new device can be used and its improvement on existing ultrasound, optical and dielectrophoresis particle manipulation systems.

The team believe the electronically controlled sonotweezers could be used in forensic science or homeland security, for applications such as cell sorting and counting of micro- and potentially nano-materials, sensing and detection and bioassay technology.

The biological applications are also interesting. For example in tissue engineering, the researchers can potentially bring together small populations of cells for multi-layered structures that better replicate such things as the lining of the lung. So whilst optical tweezers offer the potential of doing this cell by cell, the researchers can operate on groups of cells and hence produce artificial tissue on a much large scale. There is also an opportunity to bring both devices together and work across a very wide range of scales.

Professor Bruce Drinkwater said: "In all these applications, crucial processing steps require the movement of individual particles or small clusters of particles from one location to another."

Electronic sonotweezers will allow very fine control of manipulation, involving no moving parts, scaling down to microlevel, but maintaining the higher forces available from ultrasound than from optrical tweezing.

Ultrasonic manipulation of particles is an emerging and rapidly developing area and devices such as microscale filters exist already. However, these systems are limited either because they rely on resonance, effectively fixing the nodal points towards which the particles move, or they involve first trapping the particles then physically moving the transducers.

Professor Drinkwater added: "Various groups have demonstrated the basic principle and, like the work on optical tweezers in the 1980s and '90s, the race is on to develop devices to best exploit this phenomenon."

"We believe electronic sonotweezers can control bioparticles and is both safe and suitable for miniaturisation."

The electronic sonotweezers collaborative research team comprises partners from four disciplines and universities: fluid mechanics (Dr Mark Gilbertson, Bristol); transducers and system implementation (Dr Sandy Cochran, Dundee); comparison and hybridisation with optical tweezers (Dr Mike MacDonald, Dundee); particle manipulation with ultrasound (Professor Martyn Hill and R Townsend, Southampton); electronics and assay application (Professor David Cumming, Glasgow).