Spatial confinement of ultrasonic force fields in microfluidic channels.

We demonstrate and investigate multiple localized ultrasonic manipulation functions in series in microfluidic chips. The manipulation functions are based on spatially separated and confined ultrasonic primary radiation force fields, obtained by local matching of the resonance condition of the microfluidic channel. The channel segments are remotely actuated by the use of frequency-specific external transducers with refracting wedges placed on top of the chips. The force field in each channel segment is characterized by the use of micrometer-resolution particle image velocimetry (micro-PIV). The confinement of the ultrasonic fields during single- or dual-segment actuation, as well as the cross-talk between two adjacent fields, is characterized and quantified. Our results show that the field confinement typically scales with the acoustic wavelength, and that the cross-talk is insignificant between adjacent fields. The goal is to define design strategies for implementing several spatially separated ultrasonic manipulation functions in series for use in advanced particle or cell handling and processing applications. One such proof-of-concept application is demonstrated, where flow-through-mode operation of a chip with flow splitting elements is used for two-dimensional pre-alignment and addressable merging of particle tracks.

[1]  J Dual,et al.  Positioning of small particles by an ultrasound field excited by surface waves. , 2004, Ultrasonics.

[2]  Martyn Hill,et al.  The selection of layer thicknesses to control acoustic radiation force profiles in layered resonators. , 2003, The Journal of the Acoustical Society of America.

[3]  S M Hagsäter,et al.  Acoustic resonances in microfluidic chips: full-image micro-PIV experiments and numerical simulations. , 2007, Lab on a chip.

[4]  L. Gor’kov,et al.  On the forces acting on a small particle in an acoustical field in an ideal fluid , 1962 .

[5]  Kenji Yasuda.  Non-destructive, non-contact handling method for biomaterials in micro-chamber by ultrasound , 2000 .

[6]  Mattias Goksör,et al.  Optical tweezers applied to a microfluidic system. , 2004, Lab on a chip.

[7]  L. D. Rozenberg,et al.  High‐Intensity Ultrasonic Fields , 1971 .

[8]  Victor Steinberg,et al.  Continuous particle size separation and size sorting using ultrasound in a microchannel , 2006 .

[9]  Thomas Laurell,et al.  Trapping of microparticles in the near field of an ultrasonic transducer. , 2005, Ultrasonics.

[10]  H M Hertz,et al.  Ultrasonic standing wave manipulation technology integrated into a dielectrophoretic chip. , 2006, Lab on a chip.

[11]  Ultrasonic Enrichment of Microparticles in Bioaffinity Assays , 2004 .

[12]  Neil M. White,et al.  A silicon microfluidic ultrasonic separator , 2003 .

[13]  J. Kutter,et al.  Investigations on LED illumination for micro-PIV including a novel front-lit configuration , 2008 .

[14]  Jeremy J. Hawkes,et al.  Force field particle filter, combining ultrasound standing waves and laminar flow , 2001 .

[15]  H M Hertz,et al.  Proliferation and viability of adherent cells manipulated by standing-wave ultrasound in a microfluidic chip. , 2007, Ultrasound in medicine & biology.

[16]  Thomas Laurell,et al.  Chip integrated strategies for acoustic separation and manipulation of cells and particles. , 2007, Chemical Society reviews.

[17]  Thomas Laurell,et al.  Dynamic arraying of microbeads for bioassays in microfluidic channels , 2005 .

[18]  H M Hertz,et al.  Ultrasonic enhancement of bead-based bioaffinity assays. , 2006, Lab on a chip.

[19]  O. Manneberg,et al.  Temperature regulation during ultrasonic manipulation for long-term cell handling in a microfluidic chip , 2007 .

[20]  Adrian Neild,et al.  Manipulation of micrometer sized particles within a micromachined fluidic device to form two-dimensional patterns using ultrasound. , 2007, The Journal of the Acoustical Society of America.

[21]  D. Beebe,et al.  A particle image velocimetry system for microfluidics , 1998 .

[22]  A Lenshof,et al.  Acoustic resonances in straight micro channels: beyond the 1D-approximation. , 2008, Lab on a chip.

[23]  N. Riley.  Acoustic Streaming , 1998 .

[24]  Pekka Hänninen,et al.  Ultrasonic enrichment of microspheres for ultrasensitive biomedical analysis in confocal laser-scanning fluorescence detection , 2004 .

[25]  Gabriele Gradl,et al.  The potential of dielectrophoresis for single-cell experiments. , 2003, IEEE engineering in medicine and biology magazine : the quarterly magazine of the Engineering in Medicine & Biology Society.

[26]  Thomas Laurell,et al.  Noninvasive acoustic cell trapping in a microfluidic perfusion system for online bioassays. , 2007, Analytical chemistry.