Forming Three-Dimensional Colloidal Structures Using Holographic Optical Tweezers

TL;DR

This paper presents a versatile method using holographic optical tweezers to create permanent three-dimensional colloidal structures by positioning particles and inducing aggregation with electrolyte solutions, enabling rapid and cost-effective fabrication.

Contribution

Introduces a novel technique combining holographic optical trapping and electrolyte-induced aggregation to form stable 3D colloidal structures without critical point drying.

Findings

Allows formation of 3D structures both on and off substrates

Enables removal of structures from solution without drying

Technique is inexpensive, fast, and broadly applicable

Abstract

A method for forming permanent three dimensional structures from colloidal particles using holographic optical trapping is described. Holographic optical tweezers (HOT) are used to selectively position charge stabilized colloidal particles within a flow cell. Once the particles are in the desired location an electrolyte solution is pumped into the cell which reduces the Debye length and induces aggregation caused by the van der Waals attraction. This technique allows for the formation of three dimensional structures both on and away from the substrate that can be removed from solution without the aid of critical point drying. This technique is inexpensive, fast, and versatile as it relies on forces acting on almost all colloidal suspensions.