Particle Manipulation with External Field; From Recent Advancement to Perspectives

Abstract

Physical forces, such as dielectric, magnetic, electric, optical, and acoustic force, provide useful principles for the manipulation of particles, which are impossible or difficult with other approaches. Microparticles, including polymer particles, liquid droplets, and biological cells, can be trapped at a particular position and are also transported to arbitrary locations in an appropriate external physical field. Since the force can be externally controlled by the field strength, we can evaluate physicochemical properties of particles from the shift of the particle location. Most of the manipulation studies are conducted for particles of sub-micrometer or larger dimensions, because the force exerted on nanomaterials or molecules is so weak that their direct manipulation is generally difficult. However, the behavior, interactions, and reactions of such small substances can be indirectly evaluated by observing microparticles, on which the targets are tethered, in a physical field. We review the recent advancements in the manipulation of particles using a physical force and discuss its potentials, advantages, and limitations from fundamental and practical perspectives.

Interplay of acoustophoresis and dielectrophoresis in a standing surface acoustic wave field: from spherical to non-spherical particles

“…The systematic manipulation of microparticles and biological cells by acoustic wave fields developed into a flexible and scalable tool for Lab-on-a-Chip devices. With tailored acoustofluidic devices, a variety of applications for concentrating [1,2], patterning [3,4], mixing [5,6] and separating [7][8][9] of suspended particles were demonstrated, which are highly relevant in pharmacy, chemistry and biomedical fields [10][11][12]. The key of acoustic particle manipulation as a non-invasive, label-free and biocompatible method is the targeted customizability of acoustic field patterns.…”

“…Acoustic and dielectrophoretic forces have been used individually in many microfluidic devices to selectively separate spherical particles based on their size as well as mechanical and electrical properties [12,[27][28][29]. Furthermore, both forces were combined in a device using virtual deterministic lateral displacement to separate nanometer-sized particles by placing an IDT at an tilted angle beneath a micro channel [30,31].…”

On the acoustically induced fluid flow in particle separation systems employing standing surface acoustic waves – Part II

“…The active manipulation of the motion of suspended microparticles or biological cells is essential for a broad variety of applications ranging from process technologies to life science. [1][2][3] In recent years, the systematic utilization of magnetic, 4-6 electric [7][8][9] and acoustic fields 10,11 in microfluidics has enabled the development of highly customized technologies for concentrating, 12,13 patterning, 14-16 mixing [17][18][19] or sorting 1,[20][21][22] particle solutions in a flexible and scalable environment. Among these technologies, the on-chip integration of surface acoustic waves (SAWs) represents a noninvasive, label-free, biocompatible and versatile method for the precise manipulation of suspended matter through local force fields.…”