Angela Hodge Miller

Electrical and Computer Engineering

One Maryland graduate student's research could save lives by saving time. Angela Hodge Miller, who is pursuing her Ph.D. in electrical engineering, is working to develop chemical sensors capable of performing selective determination of compounds in fluids such as blood, urine and saliva. In addition to being useful in the clinical analysis process, the array of biosensors being developed by the young scientist "will be capable of performing on-chip, real-time self diagnostics," she says.

Hodge Miller's fluid analyzer will enable the diagnostic process to move more quickly and more efficiently. Currently, medical analysis for toxins involves going to a specialist, clinic or hospital, providing a sample and waiting up to two weeks for the results--a time-consuming and often costly process. "This technology will allow individuals to determine and general practitioners to perform analyses in their homes or offices," she says. "The early detection method will aid in preventing the dissemination of false information to the patient and could potentially save lives."

One instance in which the analyzer could have saved lives was during the anthrax attacks of 2001, which resulted in five deaths nationwide--including two U.S. Postal Service workers from the Washington, D.C., area--and numerous cases of severe illness among people exposed to anthrax-tainted letters. "The victims of anthrax exposure at the Brentwood postal facility could have known days ahead of time that they had been exposed," Hodge Miller says. "The hospital wouldn't have misdiagnosed them as having the flu, and they would still be alive today."

Not surprisingly, such a device is in high demand. "Many government agencies such as the National Institutes of Health and the Department of Defense, as well as private firms, believe that there is an urgent need for rapid, highly sensitive, specific, easy-to-use and cost-effective diagnostics for public health laboratories," Hodge Miller says.

In fact, there has been a strong effort by researchers in recent years to use engineering principles to solve problems related to the determination of impurities in biological fluids. However, many chemical sensors lack the capability of being applied to a broad spectrum of fluids. "Moreover," Hodge Miller says, "the majority of these sensors are incapable of performing on-chip, self-diagnostics or built-in self-tests."

Drawing upon her research in integrated-circuit technology, Hodge Miller is developing a device that functions as a capacitive-type bridge, "such that a balance can be set for a normal dielectric constant," she says. The current flowing through the transistors is unique to the fluid being tested. The dielectric constant is easily determined from the transistors' drain current, and this value can be used to distinguish between fluids being tested.

According to Hodge Miller, the transistors on which the fluid rests have openings in their gates to allow fluid to flow between a silicon substrate and a polysilicon gate where the oxide has been removed. "This allows the fluid to behave as the gate dielectric for the transistor," she says.

The biggest challenge, however, will involve determining whether the dielectric constant will be sufficient in distinguishing the properties of the fluid being studied. But so far so good. "In testing, we have seen positive results," she says.

One of Hodge Miller's long-term goals is to use the fluid analyzer to determine the levels of creatinine, a protein found in blood and urine, and blood-urine-nitrogen in those suffering from kidney disease. "Ideally," she says, "this would benefit physicians in rapidly diagnosing renal failure and in determining whether or not patients need dialysis treatment."

Additional long-term applications could be much more far reaching. Through linker chemistry or "fine-tuning," the fluid analyzer could be adjusted to detect other toxins such as anthrax or smallpox. "By applying a specific attachment chemistry to the surface of the sensor, you can isolate and identify a target protein or DNA," says Hodge Miller. "For example, with the right chemistry you can detect a specific strain of anthrax or smallpox." Hodge Miller, who became interested in biomedical engineering while still in high school, was recently chosen as the first recipient of the Fischell Fellowship, awarded to a graduate student who goes beyond scholarly achievement to produce new medical systems and devices to treat disease. The fellowship was established through a $1.25 million gift from inventor, engineer and physicist Robert Fischell.

Following in the footsteps of her father, an electrical engineer and "the most intelligent person I know," Hodge Miller received her bachelor's degree in electrical engineering from the Clark School in 1996 and her master's degree in electrical engineering from Stanford in 1998. She has interned at various government and private institutions, including the National Institute of Standards and Technology and Allied Signal Aerospace.

Looking to the future, she hopes to someday establish her own biomedical engineering consulting firm. "For me," she says, "the interest is in working in areas in which I can be creative while meeting the needs of the community at large." Her latest research is certainly a right step in that direction. --Lisa Gregory