Practical And Reliable Wireless Power Supply Design For Low Power Implantable Medical Devices
Implantable wireless devices are used to treat a variety of diseases that are not able to be treated with pharmaceuticals or traditional surgery, These implantable devices have use in the treatment of neurological disorders like epilepsy, optical disorders such as glaucoma, or injury related issues such as targeted muscle reinnervation. These devices can rely upon harvesting power from an inductive wireless power source and batteries. Improvements to how well the devices utilize this power directly increase the efficacy of the device operation as well as the device's lifetime, reducing the need for future surgeries or implantations.
I have designed an improvement to cavity resonator based wireless power by designing a dynamic impedance matching implantable power supply, capable of tracking with device motion throughout a changing magnetic field and tracking with changing powering frequencies. This cavity resonator based system presents further challenges practically in the turn-on cycle of the improved device.
I further design a coil-to-coil based wireless power system, capable of dynamically impedance matching a high quality factor coil to optimize power transfer during steady state, while also reducing turn-on transient power required in dynamic systems by utilizing a second low quality factor coil. This second coil has a broadband response and is capable of turning on at lower powers than that of the high quality factor coil. The low quality factor coil powers the circuitry that dynamically matches the impedance of the high quality factor coil, allowing for low power turn on while maintaining high power transfer at all operating frequencies to the implantable device.
Finally, an integrated circuit is designed, fabricated, and tested that is capable of smoothly providing regulated DC power to the implantable device by stepping up from wireless power to a reasonable voltage level or stepping down from a battery to a reasonable voltage level for the device. The chip is fabricated in 0.18um CMOS process and is capable of providing power to the "Bionode" implantable device.