Ultrasonic Particle Manipulation

Acoustic separation Acoustofluidics Acoustophoresis Ultrasonic concentration Ultrasonic particle manipulation Ultrasonic separation... 

Many of the reported applications of ultrasonic particle manipulation are in particle concentration or filtration. Much of the early work adopted an approach based on particle agglomeration, although the majority of recent work uses continuous flow separation. 

Hill M, Harris N (2007) Ultrasonic particle manipulation. In Hardt S, Schbnfeld F, editors. Microfluidic Technologies for Miniaturized Analysis Systems. Springer Science + Business Media LLC, New York, USA. p 357-383. 

Ultrasonic particle manipulation can also be used to enhance biosensor performance, by using the ultrasound to drive the particles of interest to the biosensor surface. In this implementation (Fig. 5), a resonant reflector layer is used to generate a pressure node at a boundary, (effectively creating a quarter wave resonance within the fluid layer), rather than in the centre of the chamber, as previously described. 

Harris N., Hill M., Shen Y, Townsend R.J., Beeby S., and White N., A dual frequency, ultrasonic, microengineered particle manipulator. Ultrasonics, 42, 139, 2004. 

There are host of studies that use ultrasonic waves in cell/particle manipulation and separation. 

Glynne-Jones P, Boltryk RJ, Harris NR, Cranny AWJ, Hill M (2010) Mode-switching a new technique for electronically varying the agglomeration position in an acoustic particle manipulator. Ultrasonics 50 68-75... 

Particle Manipulation Using Ultrasonic Fields, Fig.1 Movement of particles within an ultrasonic standing wave (USW). (a) Before a standing wave is generated, particles are evenly distributed throughout the fluid (b) a standing wave is excited by driving a transducer at... 

Particle Manipulation Using Ultrasonic Fields, Fig. 2 Enhanced sedimentation. Particles within an ultrasonic field left) are agglomerated by the field center) and then tend to sediment under gravity right)... 

Since their invention, optical tweezers have proved themselves to be very powerful interdisciplinary tools. Today they are used extensively in biophysics, as they serve as delicate tools to manipulate and study single molecules of DNA [8, 9]. Optically trapped beads have been successfully used to measure local elasticities and viscosities, for example inside cells. Ashkin [5] provides an overview of the diverse uses of optical traps as an important tool in the important areas of research. Isolation and detection of sparse cells concentration of cells from dilute suspensions separation of cells according to specific properties and trapping and positioning of individual cells for characterization are the key areas of research due to their possible impact. The non-invasive nature of particle manipulation being a key requirement, forces like hydrodynamic, optical, ultrasonic and electromagnetic have been employed for such purposes. Successful examples of the use of these optical forces for biological applications are determination... 

Particle Manipulation Using Ultrasonic Fieids, Figure 4 Particle Washing by forcing particles from one medium to another under laminar flow... 

Particle Manipulation Using Ultrasonic Fields, Rgure 5... 

Particle Manipulation Using Ultrasonic Fields, Rgure 6 Fractionation of particles, making use of the net larger force on larger particles... 

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