New Optical Particle Trap Can Easily Handle Microorganisms

In recent times, integrated optofluidic platforms have proven their worth in analyzing bacteria, viruses and other particles on a chip, but their performances are about to increase considerably. Experts at the University of California in Santa Cruz (UCSC) have created a new type of optical particle trap, which can more effectively manipulate the particles that it holds, so that scientists can take a better look at them. The find, which could bring about a new era of development in the field of biomedical analysis, has been made by scientists working at the UCSC Jack Baskin School of Engineering.

“Ultimately, it could have applications for rapid detection of bacteria and viruses in hospitals, for cell sorting in research labs, and for process monitoring in chemical engineering,” W. M. Keck Center for Nanoscale Optofluidics Director and UCSC Professor of Electrical Engineering Holger Schmidt explains. He also adds that performing fluorescence-activated cell sorting (FACS) could soon become affordable even to smaller labs, as the new technology will have the ability to create smaller and cheaper versions of the systems currently used in sophisticated machines at large labs.

“The capabilities of our optofluidic platform are continuing to grow. We have gone from the detection of single molecules and single viruses to now being able to control the movement of particles,” Schmidt says. Generally, optical traps and “optical tweezers” use the speed and momentum that photons (light particles) have, in order to influence the behavior of whatever particles or microorganisms they have in their sample. On this basic principle, UCSC researchers have previously done some modifications, which further increased their ability to manipulate particles.

The team explain that the new mechanism is fairly simple, if you know what you're doing. Essentially, the new trap is nothing more than a hollow-core optical waveguide, which has the ability to make light flow through liquid-filled channels on chips. Any particles inserted in the waveguide are then illuminated with lasers from both ends of the channels, and basically remain in equilibrium where the laser intensities are equal. By changing the power of the two lasers, the particles can be moved up and down, without having the possibility to escape.

“We can also use this like an optical leaf blower to push all the particles in a sample to the same spot and increase the concentration. The goal is to control the position and movement of particles through channels on a chip so they can be studied using fluorescence analysis and other optical methods,” Schmidt concludes.