Their invention, which is forthcoming in the paper version of the journal Lab on a Chip, works much the way a coin sorter does, only on a microscopic scale, screening for particles purely by size. This renders sample sizes and concentration levels almost irrelevant, because particles are trapped by size, not number, thereby allowing for much earlier detections of viruses.
"Most of the tests that you're given are fairly inaccurate unless you have a really high concentration of the virus," Aaron Hawkins, professor of electrical and computer engineering at BYU and supervisor of the chip design, said in a statement. "One of the goals in the 'lab on a chip' community is to try to measure down to single particles flowing through a tube or a channel."
And now, in just the past few weeks, Hawkins tells me the team has managed to overcome one of their biggest challenges--interfacing the large fluid amounts of the macro world with the tiny fluid amounts of the micro world. He says they've come up with a way to use macro volumes of fluid on their micro chip by gluing plastic reservoirs onto the chip and "precision-aligning them."
The chip works much in the way coin sorters do; volumes of liquids can flow over the chip until they hit a wall, at the bottom of which is a thin slot whose size is precisely a tiny amount smaller than the particle being measured. The specifically sized particles that are trapped against the wall form a line visible with a special camera.
The researchers say that capturing single particles can also be useful beyond the detection of a virus or protein. David Belnap, an assistant professor of chemistry and co-author of the paper, says that a chip like theirs could also advance the pace of research, allowing scientists to consistently obtain pure samples essential for close inspection of viruses and virus behavior.
Typically, the cost to make small and precise enough chips with nanosize parts is in the millions. The group at BYU got around this barrier using a more simple machine to form two dimensions in micrometers (micro being 1,000 times larger than nano). They then added a 50-nanometer-thick (or is it thin?) layer of metal to the chip, which they topped with glass deposited by gasses, and used an acid to wash away the thin metal, which left the narrow gap in the glass to trip the virus.
Hawkins says his team is now gearing up to make chips with multiple, progressively smaller slots, so that a single sample can be used to screen for particles of varying sizes. One could fairly simply determine which proteins or viruses are present based on which walls have particles stacked against them.
After this is developed, Hawkins says, "If we decided to make these things in high volume, I think within a year it could be ready."