Share & Connect
Last week, at the International Solid-State Circuits Conference (ISSCC), electrical engineer Ada Poon reported that she has developed a wireless device that swims through the blood-stream and delivers medicine throughout the body.
“Such devices could revolutionize medical technology,” Poon states in the Stanford University news release. Poon works as an assistant professor at the Stanford School of Engineering. She states, “Applications include everything from diagnostics to minimally invasive surgeries.”
Prior, implanted medical devices (such as pacemakers and cochlear implants) were usually powered by battery, and were heavy and stationary. Poon’s device, on the other hand, is wireless and self-propelled; it does not require batteries or cables to keep itself energized, and is instead powered by electromagnetic radio waves that come from a radio transmitter outside the body. According to Stanford University,
“The transmitter and the antennae [from the device] are magnetically coupled such that any change in current flow in the transmitter produces a voltage in the other wire – or, more accurately, it induces a voltage.”
Wireless implantable devices are not a new concept. Scientists have been working on this sort of device for half a century, using Maxwell’s equations– which consist of a set of equations that explain the fundamentals and relationship between electricity and magnetism– to perform calculations. However, scientists have stopped due to the equations results, which expressed that radio waves would exponentially decrease as it traveled through the body.
Poon identified several mistakes in their calculations. The scientists had assumed the body acted as a good conductor of electricity. It turns out that it is not so. Poon, instead, viewed the body as dielectric – a good electric insulator. Collaborating with graduate students David Pivonka and Anatoly Yakovlev, she used a different set of equations, from which she realized radio waves can still move through tissue and not decrease in energy. She further discovered that they can travel much farther than she or anyone previously expected.
Poon then developed two types of the self-propelled device. One powers itself by driving an electric current directly in the blood, propelling itself five centimeters per second. The other produces a current goes that back and forth through a loop of wire. It produces whooshing motion as maneuvers as if it were a kayak.
“There is considerable room for improvement and much work remains before such devices are ready for medical applications,” says Poon. “But for the first time in decades the possibility seems closer than ever.”