Charging demo. Large coil on the right is connected to wall AC power. It is transmitted to the receiving coil. The small coil to the left is connected to a heart pump submerged in water. Via University of Washington
Wireless power transfer is being pushed harder than ever. From magnetic harmonics to ultrasound, many different options are being explored. Once an efficient option surfaces, the world of electrical devices will change dramatically. For example, Toyota wants to setup wireless charging stations for their hybrids. Partner company Witricity is planning wide distribution for ever device in the home. Now researchers at two universities want to get a jump on the fledgling technology and bring wireless power to medical implants.
There are many medical implants that require a battery pack. In some cases, the battery is inside and lasts for years. In other cases, wires protrude from the skin for either direct power or charging that often contract infection. At the moment, internal body energy harvesting is still in the experimental stage. The team from the University of Pittsburgh Medical Center and University of Washington (UW) are looking to current wireless technology to fill the demand.
UW professor of computer science and electrical engineering Joshua Smith is testing wireless induction power transfer. The challenge is to send the power to a device that is not fixed, and possibly move inside the transmitters radius. With most currently available inductive charging systems, devices must remain fixed to a extremely close position for maximum power transfer. The PowerMat and HP Touchstone are perfect examples. The cellphones/tablets bring the coupling coils within millimeters of each other.
Smith's system uses something akin to Nikola Tesla's frequency matching experiments. By matching frequencies between the transmitting and receiving coils, Smith is able to maintain a near lossless power transfer over a distance equal to the diameter of the coils. 1 meter with a 1 meter diameter coil, for example. As distance or orientation changes between coils, Smith's system will adjust frequency to keep the efficient power transfer going. Smith said, "Most people's intuition about wireless power is that as the receiver gets further away, you get less power. But with this technique there's a regime where the efficiency actually doesn't change with distance."
Smith and his colleagues showed off the technology at the American Society for Artificial Internal Organs meeting in Washington D.C. Their model powered an artificial heart pump with a 1.7" (4.3 cm) coil. Although 1.7" is not far, it is far enough to penetrate through the skin. The device demonstrated 80% power efficiency.
Paired with an internal storage battery, patients could be cord and charger free for lengths of time depending on charge density. This is sure to take the implant power industry by storm.