Trapping/Pinning of colloidal microspheres over glass substrate using surface features

TL;DR

This paper introduces a microstructure-based method to trap and pin colloidal microspheres with high spatial accuracy, facilitating studies of collective phenomena and biosensor applications beyond traditional optical trapping limitations.

Contribution

The authors develop a novel technique using microstructured surfaces to trap colloidal microspheres, overcoming the throughput limitations of optical tweezers.

Findings

Effective trapping of microspheres over microstructures.

High spatial accuracy in particle positioning.

Potential applications in biosensing and collective behavior studies.

Abstract

Suspensions of micro and nano particles made of Polystyrene, Poly(methyl methacrylate), Silicon dioxide etc. have been a standard model system to understand colloidal physics. . These systems have proved useful insights into phenomena such as self-assembly. Colloidal model systems are also extensively used to simulate many condensed matter phenomena such as dynamics in a quenched disordered system and glass transition. A precise control of particles using optical or holographic tweezers is essential for such studies. However, studies of collective phenomena such as jamming and flocking behaviour in a disordered space are limited due to the low throughput of the optical trapping techniques.In this article, we present a technique where we trap and pin polystyrene microspheres ~ 10 {\mu}m over triangular-crest shaped microstructures in a microfluidic environment. Trapping/Pinning occurs due to the combined effect of hydrodynamic interaction and non-specific adhesion forces. This method allows trapping and pinning of microspheres in any arbitrary pattern with a high degree of spatial accuracy which can be useful in studying fundamentals of various collective phenomena as well as in applications such as bead detachment assay based biosensors.