Dripping faucets inspire new way of creating structured particles

Researchers at MIT and the University of Central Florida (UCF) have developed a versatile new fabrication technique for making large quantities of uniform spheres from a wide variety of materials - a technique that enables unprecedented control over the design of individual, microscopic particles.

The particles, including complex, patterned spheres, could find uses in everything from biomedical research and drug delivery to electronics and materials processing.

The method is an outgrowth of a technique for making long, thin fibres out of multiple materials, developed over the last several years at MIT by members of the same team.

The new work, reported this week in the journal Nature, begins by making thin fibers using this earlier method, but then adds an extra step of heating the fibres to create a line of tiny spheres - like a string of pearls - within these fibres.

Conventional fabrication of microscopic spherical particles uses a ''bottom-up'' approach, growing the spheres from even tinier ''seeds'' - an approach that is only capable of producing very tiny particles.

This new ''top-down'' method, however, can produce spheres as small as 20 nanometers (about the size of the smallest known viruses) or as large as two millimeters (about the size of a pinhead), meaning the biggest particles are 100,000 times larger than the smallest ones. But for a given batch, the size of the spheres produced can be extremely uniform - much more so than is possible with the bottom-up approach.