Researchers have invented a technique that uses inexpensive paper to make "microfluidic" devices for rapid medical diagnostics and chemical analysis.
The innovation enhances commercially available diagnostic devices that use paper-strip assays like those that test for diabetes and pregnancy.
"With current systems that use paper test strips you can measure things like pH or blood sugar, but you can't perform more complex chemical assays," said Babak Ziaie, a Purdue University professor of electrical and computer engineering and biomedical engineering. "This new approach offers the potential to extend the inexpensive paper-based systems so that they are able to do more complicated multiple analyses on the same piece of paper. It's a generic platform that can be used for a variety of applications."
Current lab-on-a-chip technology is relatively expensive because chips must be specifically designed to perform certain types of chemical analyses, with channels created in glass or plastic and tiny pumps and valves directing the flow of fluids for testing.
The chips are used for various applications in medicine and research. But the chips, which are roughly palm-size or smaller, are difficult to design and manufacture.
The new technique's testing platform will be contained on a disposable paper strip containing patterns created by a laser. The researchers start with paper having a hydrophobic - or water-repellant - coating, such as parchment paper or wax paper used for cooking. A laser is used to burn off the hydrophobic coatings in lines, dots and patterns, exposing the underlying water-absorbing paper only where the patterns are formed. The new approach is within a research area called paper microfluidics.
"Other techniques in paper microfluidics are more complicated," Ziaie said. "Our process is much easier because we just use a laser to create patterns on paper you can purchase commercially and it is already impregnated with hydrophobic material. It's a one-step process that could be used to manufacture an inexpensive diagnostic tool for the developing world where people can't afford more expensive analytical technologies."