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nanotimes News in Brief Engineering //

Wireless, Self-Propelled Medical Device © Based on Material by Andrew Myers / Ada Poon / Stanford University

12-02 :: February/March 2012

engineering at Stanford University, demonstrated a tiny, wirelessly powered, self-propelled medical device capable of controlled motion through a fluid – blood. Powered without wires or batteries, it can propel itself though the bloodstream and is small enough to fit through blood vessels.

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“Such devices could revolutionize medical technolo- gy,” said Poon. “Applications include everything from diagnostics to minimally invasive surgeries.”

The idea of implantable medical devices is not new, but most of today‘s implements are challenged by the size of their batteries, which are large and hea- vy and must be replaced periodically. Fully half the volume of most of these devices is consumed by battery.

“While we have gotten very good at shrinking elec- tronic and mechanical components of implants, en- ergy storage has lagged in the move to miniaturize,” said co-author Teresa Meng, a professor of electrical engineering and computer science. “This hinders us in where we can place implants within the body and also creates the risk of corrosion or broken wires, not to mention replacing aging batteries.”

Stanford electrical engineers have created a tiny wireless chip, driven by magnetic currents, that‘s small enough to travel inside the human body. They hope it will be used for a wide range of biomedical applications, from delive- ring drugs to cleaning arteries. © Stanford

t International Solid-State Circuits Conference, Ada Poon, an assistant professor of electrical

Poon‘s devices are different. They consist of a radio transmitter outside the body sending signals inside the body to an independent device that picks up the signal with an antenna of coiled wire. The transmitter and the antennae are magnetically coupled such that any change in current flow in the transmitter produ- ces a voltage in the other wire – or, more accurately, it induces a voltage. The power is transferred wire-