ARLINGTON, Va., Nov. 11, 2002 - Bioengineers at Pennsylvania State University have developed an ultrasound insulin delivery system that can be worn as a patch on the body.

Currently, diabetics must either inject insulin via hypodermic needles or use a mini-pump with a needle or a soft tube inserted just under the skin. The new ultrasound patch offers a less painful and noninvasive alternative because it doesn't break the skin.

Similar drug delivery devices on the market use a probe about 8 inches long and weigh more than 2 pounds. The new ultrasound patch operates in the same frequency range as the large commercially available devices, but the entire system is about the size and weight of a matchbook and would allow patients greater mobility while receiving insulin.

The key to the new ultrasound patch is a "cymbal" transducer. A prototype patch uses four cymbal transducers, which consist of a thin disk of piezoelectric ceramic material sandwiched between titanium end caps shaped like cymbals.

The transducers produce ultrasonic waves that open microscopic channels in the skin. A thin reservoir of insulin is placed in front of the cymbal transducers, and when a current is applied, the ultrasonic waves, which are just above the level of human hearing, push the medication through the channels in the skin and into the blood stream.

Live rat experiments, the results of which were presented last month at the IEEE 2002 Ultrasonics Symposium in Munich, Germany, have shown that the ultrasound patch delivers therapeutically effective doses of insulin.

Preliminary results also showed that the patch may be far more efficient than first thought, said Nadine Smith, Ph.D., a project leader and assistant professor of bioengineering at Penn State. Researchers have been able to reduce the exposure time--already down from 60 minutes to only 20 minutes--while still delivering the same amount of insulin.

"We are hopeful that, eventually, we may be able to tune the system so that one to five minutes of exposure may be enough" to deliver an effective dose of insulin, Smith said.

Besides insulin, some pain relievers, asthma drugs, hormones, medications used to treat AIDS and other drugs that cannot be taken by mouth might be delivered via the new ultrasound patch, Smith said. The insulin patch could be used to treat both Type I and Type II diabetes. Eventually the device could be paired with similar ultrasound glucose monitoring devices currently under development.

Research describing the new prototype in detail was published in the October issue of the IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control. A paper has been accepted for publication in an upcoming issue of Ultrasound in Medicine and Biology. One of the co-authors, bioengineering professor K. Kirk Shung, recently completed a 3-year, Special Opportunity grant from the foundation to develop research and education in medical ultrasonic transducer engineering at Penn State.

The Whitaker Foundation is also supporting Smith in a research project using ultrasound to treat prostate cancer and disease.

Nadine Smith, Penn State University
Mark Bowman, Whitaker Foundation