This month’s Medical Device and Diagnostic Industry (MD+DI) magazine carried an interesting article by David Schatz – WiTricity’s VP Sales – on their efforts to develop highly resonant wireless power transfer technology for use in AIMDs. The article is available online at http://www.mddionline.com/article/wireless-power-medical-devices.
The article mentions the work that WiTricity has been doing with Thoratec to wirelessly power a HeartMate II® LVAD, and which was announced back in May 2011. David told me that for this project, WiTricity has been able to transfer 20 Watts over 20 cm, with SAR and temperature-rise compliance, and without the use of resonant repeaters.
If these levels scale well to small receiver units, I believe that this technology would enable not only the development of deep-implant AIMDs that are currently outside the range of classical resonant-inductive TET, but would also allow the development of more patient-friendly rechargeable AIMDs that don’t require dedicated recharge sessions, but rather receive their charge from a WiTricity transmitter under the patient’s bed while the patient sleeps. From the MD+DI article:
“A circulatory assist device like an LVAD is just one example of a medical device that can harness the benefits of highly resonant wireless power transfer. There is also promise for other implanted devices, including neurostimulators, implantable defibrillators and pacemakers, implantable drug-delivery pumps, electronic ophthalmic and cochlear implants, and rechargeable hearing aids.
In this broad range of implanted medical devices, high-resonance wireless power transfer can enable higher charge rates than would be possible with traditional magnetic induction. Higher charge rates allow for device implantation deeper within the body and enable more flexible charger configurations outside of the body.
For example, the wireless charger for ophthalmic or cochlear implants could be deployed in a pair of eyeglasses or a pillow. The wireless charger for a neurostimulator implanted in the lower back could be deployed in a chair or bed. Hearing aids could be recharged by simply placing them in a charging box on one’s nightstand, without requiring precise fixturing or galvanic contacts as do today’s rechargeable hearing aids.”