Ultrasonic standing wave manipulation technology integrated into a dielectrophoretic chip

Abstract

Several cell-based biological applications in microfluidic systems require simultaneous high-throughput and individual handling of cells or other bioparticles. Available chip-based tools for contactless manipulation are designed for either high-precision handling of individual particles, or high-throughput handling of ensembles of particles. In order to simultaneously perform both, we have combined two manipulation technologies based on ultrasonic standing waves (USWs) and dielectrophoresis (DEP) in a microfluidic chip. The principle is based on the competition between long-range ultrasonic forces, short-range dielectrophoretic forces and viscous drag forces from the fluid flow. The ultrasound is coupled into the microchannel resonator by an external transducer with a refractive element placed on top of the chip, thereby allowing transmission light microscopy to continuously monitor the biological process. The DEP manipulation is generated by an electric field between co-planar microelectrodes placed on the bottom surface of the fluid channel. We demonstrate flexible and gentle elementary manipulation functions by the use of USWs and linear or curved DEP deflector elements that can be used in high-throughput biotechnology applications of individual cells.

On-chip manipulation of single microparticles, cells, and organisms using surface acoustic waves

“…To date, many acoustic-based particle manipulation functions (e.g., focusing, separating, sorting, mixing, and patterning) have been realized (25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43). None of these approaches, however, have achieved the dexterity of optical tweezers; in other words, none of the previous acoustic-based methods are capable of precisely manipulating single microparticles or cells along an arbitrary path in two dimensions.…”

Acoustofluidics 23: acoustic manipulation combined with other force fields

“…Wiklund et al 44 first demonstrated the integration of both acoustophoretic and DEP particle manipulation within a microfluidic device, as shown in Figure 5. Acoustic standing waves were set up across the width of the channel, to assemble linear arrays and aggregates of particles, which could then be further manipulated by DEP produced by co-planar electrodes at the bottom of the channel.…”

On-Chip Fluorescence-Activated Cell Sorting by an Integrated Miniaturized Ultrasonic Transducer

“…Other ways to obtain separation is by displacing the particles in the out-of-plane direction 33 or by exciting a fluid channel mode by an external transducer. 22,34 In order to manipulate cells individually in a flow, the acoustic energy needs to be localized to a small zone as is obtained for the integrated miniaturized transducers.…”