48

nanotimes News in Brief

11-05 :: May/June 2011

Lab-on-Chip // New LOC Advance Uses Low-cost, Disposable Paper Strips

©Text: Emil Venere / Purdue University R

esearchers have invented a technique that uses inexpensive paper to make “microfluidic”

devices for rapid medical diagnostics and chemical analysis.

The innovation represents a way to enhance com- mercially available diagnostic devices that use pa- per-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 applica- tions.”

Findings are detailed in a research paper published in the journal Lab on a Chip.

Current lab-on-a-chip technology is relatively ex- pensive 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 being used for various applications in medicine and research, measuring specific types of cells and molecules in a patient‘s blood, monitoring microorganisms in the environment and in foods, and separating biological molecules for laboratory analyses. But the chips, which are roughly palm-size or smaller, are difficult to design and manufacture.

The new technique is simpler because the testing platform will be contained on a disposable paper strip containing patterns created by a laser. The re- searchers start with paper having a hydrophobic – or water-repellant – coating, such as parchment paper or wax paper used for cooking.

“We can buy this paper at any large discount retail store,” Ziaie said. “These patterns can be churned out in the millions at very low cost.”

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.