Manipulation of particles in two dimensions using phase controllable ultrasonic standing waves

Courtney, C.R.P., Ong, C.K., Drinkwater, B.W., Bernassau, A.L., Wilcox, P.D. and Cumming, D.R.S. (2012) Manipulation of particles in two dimensions using phase controllable ultrasonic standing waves. Proceedings of the Royal Society of London Series A: Mathematical, Physical and Engineering Sciences, 468(2138), pp. 337-360. (doi: 10.1098/rspa.2011.0269)

Abstract

The ability to manipulate dense micrometre-scale objects in fluids is of interest to biosciences with a view to improving analysis techniques and enabling tissue engineering. A method of trapping micrometre-scale particles and manipulating them on a two-dimensional plane is proposed and demonstrated. Phase-controlled counter-propagating waves are used to generate ultrasonic standing waves with arbitrary nodal positions. The acoustic radiation force drives dense particles to pressure nodes. It is shown analytically that a series of point-like traps can be produced in a two-dimensional plane using two orthogonal pairs of counter-propagating waves. These traps can be manipulated by appropriate adjustment of the relative phases. Four 5 MHz transducers (designed to minimize reflection) are used as sources of counter-propagating waves in a water-filled cavity. Polystyrene beads of 10 μm diameter are trapped and manipulated. The relationship between trapped particle positions and the relative phases of the four transducers is measured and shown to agree with analytically derived expressions. The force available is measured by determining the response to a sudden change in field and found to be 30 pN, for a 30 Vpp input, which is in agreement with the predictions of models of the system. A scalable fabrication approach to producing devices is demonstrated.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Cumming, Professor David and Bernassau, Dr Anne
• Authors: Courtney, C.R.P., Ong, C.K., Drinkwater, B.W., Bernassau, A.L., Wilcox, P.D., and Cumming, D.R.S.
• College/School: College of Science and Engineering > School of Engineering > Electronics and Nanoscale Engineering
• Journal Name: Proceedings of the Royal Society of London Series A: Mathematical, Physical and Engineering Sciences
• ISSN: 1364-5021
• Published Online: 28 September 2011