Scientists develop new micropump for hand-held medical devices

In an advance toward analyzing blood and urine instantly at a patient's bedside instead of waiting for results from a central laboratory, scientists are reporting development of a new micropump capable of producing pressures almost 500 times higher than the pressure in a car tire. Described in ACS' journal Analytical Chemistry, the pumps are for futuristic "labs-on-a-chip," which reduce entire laboratories to the size of a postage stamp.

Shaorong Liu and colleagues explain that powerful pumps are critical for high performance liquid chromatography (HPLC), a mainstay laboratory testing technology used in medical diagnosis, drug screening and numerous other purposes. HPLC can analyze 80 percent of all known chemical compounds. Scientists are trying to miniaturize HPLC for handheld devices, which would eliminate the need to send samples to central labs and wait for the results. One stumbling block, however, is the lack of suitable small, powerful pumps to push samples through HPLC devices.

They describe invention of a device six times more powerful than the best existing pump of this kind. Linked together in series, their electroosmotic pumps can produce more than 17,000 pounds per square inch of pressure. The pumps use electroosmotic flow, in which an electrical current makes charged particles flow through a narrow channel. The new pumps could produce even higher pressures, the scientists report.