Micrometric and sub-micrometric contaminant particles—what most of us call “dust”—are everywhere.
Dust makes it tough to keep the house clean, but it also causes problems for art conservators, the electronics industry, and aerospace engineers. Now, scientists want to use static cling and the science behind gecko feet to develop a tool that could help fight dust.
T. Kyle Vanderlick, dean of the School of Engineering and Applied Science at Yale University, took on the dust problem shortly after the university established art conservation labs at its Institute for the Preservation of Cultural Heritage (IPCH).
Dust is a particular problem when it comes to modern paintings that feature acrylic paint, says Cindy Schwarz, assistant conservator of painting at the Yale University Art Gallery.
“Acrylic paints are incredibly porous, so anything you’re putting on the surface could get into the pores, and then work from the insides of the pores to soften the paints,” she says.
New technology, described in the journal ACS Applied Materials and Interfaces, has the potential to solve the long-standing problem.
If dust particles are bigger than 10 micrometers, you can remove them with minimal fuss, usually with an air jet or nitrogen jet. It’s a whole other world of trouble for particles less than 10 micrometers. There are plenty of removal methods, but each has its drawbacks. Wet cleaning is limited in its ability to remove particles, and can possibly damage the object being cleaned.
In recent years, the electronics industry and art conservators have turned to dry cleaning techniques, such as lasers, micro-abrasive particles, and carbon dioxide snow jets. They remove dust well, but can be just as damaging to artwork as wet cleaning methods.
The solution is deceptively simple. In the lab, Hadi Izadi, a postdoctoral associate and the paper’s lead author, says the secret is what looks like an ordinary plastic sheet, but is actually an elastic and non-sticky polymer called polydimethylsiloxane (PDMS).
Put it under a microscope, and you can see millions of tiny columns. Depending on the size of dust particles you’re removing, the pillars range from 2 to 50 micrometers in diameter—bigger particles require bigger pillars.
Izadi is familiar with fibrillar structures and micropillars. His previous research explored the mystery of how geckos effortlessly stick to walls. It turns out that a lot of it has to do with electrostatic charges and the microscopic pillars on the pads on their feet. Applying some of this science to cleaning microparticles makes sense, he says. “When you’re talking about dust, you’re talking about electrostatic charges.”
The micropillar structures used for dust cleaning, however, differ from those of geckos in that they’re designed specifically not to stick. The PDMS polymer has minimal interaction with the substrate—whether it’s an iPhone or a sculpture—but it produces enough electrostatic charge to detach the dust particles.
Once you match up a sheet with the appropriately sized pillars, cleaning is simply a matter of tapping the polymer on the surface. Particles absorbed by the polymer go around the pillars. Tests on various surfaces in the lab have shown total cleaning of silica dust particles and no damage to the surface.
“Dust is something at the nanometer level,” Vanderlick says. “And there’s a lot of interesting thin film, surface, and interfacial physics associated with the preservation of art.”
Source: Yale University