New devices offer therapy on the go

Microcircuits are making some powerful medical devices small and portable enough for extended use to treat everything from joint pain to tumors.

Several of the innovations use sound waves to carry out therapy.

One is a portable ultrasound device to treat joint pain. Of course, ultrasound gear has been used to help people with arthritis or other chronic joint pain for years.

But the gear designed by George Lewis, a biomedical engineering graduate student at Cornell University, is a far cry from the bulky, costly machines used in doctor's offices and rehab clinics.

"We've got it down to about the size of a pager or iPod, plus a quarter-sized ceramic transducer that actually delivers the sound waves," Lewis said. "What we're really hoping is that this kind of portable pain relief will enhance mobility - people will put it on and have less pain and feel like moving around again."

The device, which is about to go into human clinical trials, succeeds by its efficiency. Lewis has found a way to convert 95 percent of battery power into sound waves; most ultrasound devices are only 50 percent efficient.

"Depending on how high the dose is set, we think we can get four to eight hours of therapy out of a single battery charge, and it only takes 20 or 30 minutes to recharge the batteries," Lewis said.

He has tested people using the device while running, rowing and biking. "We're delivering a smaller dose of ultrasound than most devices on the market, but by being able to wear it right next to the knee or elbow or back, it can do more," he said.

Cornell will license the device - developed with support from the National Science Foundation - to a company that can bring it to market. Lewis said he has been building the prototypes for about $100 each.

Besides relieving pain, Lewis and his physician collaborators at Weill Cornell School of Medicine think the miniature sound-wave generator might be used to help deliver medicine through the skin or to activate implanted treatments, like breaking up wafers of cancer-killing drugs left behind after surgery.

At MIT, mechanical engineers are well on their way to doing an end run around the problem of white-coat hypertension - the tendency among certain patients to see their blood pressure spike whenever they go see their doctor.

The alternative is a blood-pressure sensor that loops around the wrist and index finger and measures the speed of blood moving along an artery between the two points.

The device is just as accurate as the traditional blood pressure cuff, researchers say, but since it's less cumbersome, it can be worn for hours or even days. "The cuff only gives snapshot data; this gives you signals over an extended period so you can see trends and capture the physical condition quite well," said Harry Asada, a mechanical engineer who led the development team. Signals with results from the device can be transmitted by radio or wireless Internet.

Finally, there is the tattletale pill, designed by engineers at the University of Florida.

It consists of a standard gel capsule that includes a tiny microchip and digestible antenna. Once a patient takes the pill, it sets off a weak electrical signal that can be picked up by a small receiver carried or worn by the patient, which in turn sends a phone or Web message to doctors or family members that the medicine has been taken.

The designers say such smart pills are needed both to help ensure consistency in dosing for drug tests and to ensure compliance among patients who may forget or even resist taking medicines at the required time.

Researchers have so far tested the pills only in lab models and with cadavers, but a University of Florida spinoff company is working on commercial development and human clinical trials needed for approval of the devices from the Food and Drug Administration.