Flexible acoustic particle manipulation device with integrated optical waveguide for enhanced microbead assays

Abstract

Realisation of a device intended for the manipulation and detection of bead-tagged DNA and other bio-molecules is presented. Acoustic radiation forces are used to manipulate polystyrene micro-beads into an optical evanescent field generated by a laser pumped ion-exchanged waveguide. The evanescent field only excites fluorophores brought within ~100 nm of the waveguide, allowing the system to differentiate between targets bound to the beads and those unbound and still held in suspension. The radiation forces are generated in a standing-wave chamber that supports multiple acoustic modes, permitting particles to be both attracted to the waveguide surface and also repelled. To provide further control over particle position, a novel method of switching rapidly between different acoustic modes is demonstrated, through which particles are manipulated into an arbitrary position within the chamber. A novel type of assay is presented: a mixture of streptavidin coated and control beads are driven towards a biotin functionalised surface, then a repulsive force is applied, making it possible to determine which beads became bound to the surface. It is shown that the quarter-wave mode can enhance bead to surface interaction, overcoming potential barriers caused by surface charges. It is demonstrated that by measuring the time of flight of a microsphere across the device the bead size can be determined, providing a means of multiplexing the detection, potentially detecting a range of different target molecules, or varying bead mass.

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Identifiers

ORCID for Peter Glynne-Jones: orcid.org/0000-0001-5684-3953

ORCID for Martyn Hill: orcid.org/0000-0001-6448-9448

ORCID for James S. Wilkinson: orcid.org/0000-0003-4712-1697

ORCID for Nicholas R. Harris: orcid.org/0000-0003-4122-2219

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