No pain, big gain

Tests would be painless and results nearly instantaneous, say developers at Sandia National Laboratories.

The first device, called ElectroNeedles, contains micron-sized electrodes capable of measuring molecules such as glucose. The other is Posts, basically consisting of micron-sized posts for measuring proteins and other macromolecules, including protein markers released during a heart attack.

In practice, tips of the ElectroNeedles and Posts would be coated with a biologically active layer capable of measuring concentrations of specific lipids, proteins, antibodies, toxins, viruses, and carbohydrates such as glucose. A measurement takes a few seconds using the ElectroNeedles and rapid electrochemical methods for analysis. Likewise, coated Posts can capture proteins and other nonredox molecules for optical measurement in less than a half hour.

Both devices can be tailored to sample different portions of the skin. For example, devices with shorter "prickly parts" could measure lowmolecularweight compounds such as glucose in the upper skin layer. Devices with longer stickers could assay larger molecules in the blood, such as Troponin I, a key protein released during a heart attack.

"Today when someone goes to an emergency room with chest pains the doctor assesses the patient's condition based on their symptoms. An accurate diagnosis requires a blood sample, which typically goes to an off-site laboratory for analysis, a process that takes about 6 hr," says Project Lead Jeb Flemming. A Post test, in contrast, would let ER doctors know within minutes whether a patient has elevated Troponin I levels, because most of the diagnostics can take place during the ambulance ride. Best of all, "There would be little to no pain associated with the tests," Flemming says. "The only thing the patient would feel is a slight itching."

Both devices now exist as prototypes made of Foturan, a glasslike material. The intent is to mass produce them from an inexpensive plastic.