Sandia Lab News
January 16, 1998

'Lab-on-a-chip' efforts show progress

14-month technical review is favorable

Neal Singer

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LAB ON A CHIP DESIGN - Top level view shows pushbutton controls and viewing screen; mid-level encasements perform (l to r) computation and power management; and bottom (l to r) are pumps, gas and liquid analysis channels, and batteries.
The effort by Sandia researchers to build a self-contained chemistry laboratory in a handheld device received high marks as well as guidance in the project's second review by an independent panel at Sandia/California in December.

The intent is to create a user-friendly analyzer that quickly will characterize chemical agents in both gasses and liquids.

"We saw considerable technical progress and were pleased by it," said panel chair Richard Zare, a Stanford University chemistry professor who also is chair of the National Science Board, a 24-member multidisciplinary group appointed by the President and confirmed by the US Senate to advise them of the views of scientific and engineering leaders in all areas of the nation. The Board also serves as the governing body of the National Science Foundation.

The fourteen-month-old "µChemLab" project, led by John Vitko (8102), Al Sylwester (1845), Terry Michalske (1114), and Phil Bennett (9651), is funded for three years by Sandia's Laboratory Directed Research and Development program. ("µ" is a Greek letter used by researchers as a symbol for "micro.")

A near-term demonstration device is conceived to be little bigger than a pocket calculator, battery-powered, with a single readout, and operated by five pushbutton controls.

To increase its sensitivity, the µChemLab preconcentrates airborne materials as it sucks them in. The materials then are analyzed chemically, using a chromatograph and an array of selectively coated acoustic sensors whose frequencies shift as mass deposits on them.

The array of coatings allows sensors to respond to a wide variety of chemical compounds. "The resulting frequency shifts serve as fingerprints for the different chemicals," says John.

Liquid samples are introduced through an external port, passed through a separations column slightly wider than a human hair, and then analyzed by microfabricated laser diodes and lenses.

Depending on the view of the research scientists or the review panel, the device will use either gas and liquid phase channels to analyze different classes of samples, or use both the gas and liquid phase analyses to interrogate the same sample, using evidence from one to help analyze the other.

The panel strongly favored the joint analysis approach.

Panel members evaluating the work of Sandia staff were chair Zare, Eric Koglin (Environmental Protection Agency), Major Paul Schaudies (ret., Science Applications International Corporation), Sal Bosco (Office of the Secretary of Defense), Lloyd Burgess (University of Washington), Peter Hesketh (University of Illinois Chicago), Chris Aldridge (5861, formerly National Institute of Justice), and James Horton (Office of the Secretary of Defense).

Other discussions described progress in making tiny containers, channels, and valves that must maneuver such small quantities of fluids that ordinary understandings of flow do not apply.

Critical issues of the gas analysis phase were discussed by Greg Frye (1315) and Steve Casalnuovo (1313), and of the liquid phase by Dave Rakestraw and Don Arnold (both 8358).

The implementation strategy and scheduling discussion was led by Scott Carichner (8120).

The next panel review is scheduled for May 1998.

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