Wireless power and data telemetry for retinal prosthesis

Retinitis Pigmentosa (RP) and Age-related Macular Degeneration (AMD) are incurable retinal diseases that result in profound vision loss due to degeneration of the light sensing photoreceptor cells. The discovery that electrical stimulation of retinal neurons creates visual perception in patients, however, has inspired research on an electronic prosthetic device capable of bypassing the damaged photoreceptors. In such a device, three telemetry links are needed: forward power telemetry, forward data telemetry and reverse data telemetry.; This thesis proposes a dual band wireless power and bi-directional data telemetry system to implement the above three telemetry links for retinal prosthesis.; To achieve high power efficiency, the major components for inductive power transmission, including power amplifier, coils, and power recovery circuits, are analyzed and optimized in the thesis. A prototype system is implemented, which can transmit up to 250 mW with efficiency up to 75%. The coil pair used for power transmission is reused for reverse data telemetry, with the LSK modulation techniques. It can achieve a data rate of 3.3 kbps with a packet error rate of 10-6. For an inductive link, one of the major challenges is the coupling and loading variations, which can result in either overheating due to excessive power or malfunctioning due to insufficient power in the implant. An adaptive power telemetry system is proposed, analyzed and implemented. It uses the reverse data telemetry to transmit the power level information from the implant to the external unit and the external power controller can transmit 'just-needed' power to the implant regardless of the coupling and loading variations.; It is challenging for an inductive link to achieve both high forward data rate and high power transmission efficiency. To address this challenge, the data carrier uses a frequency higher than the power carrier, creating a dual band system where the data rate is not limited by the low carrier frequency requirement for power transmission. The interaction between the power transfer and data transfer is analyzed with a design methodology proposed for maximizing the data signal magnitude. A prototype of such a dual band system is built for retinal prosthesis and the feasibility is verified. For data modulation, a novel phase shift keying (PSK) modulator is proposed. The modulator can modulate phase within two carrier cycles regardless of the Q of the transmitter. A prototype is implemented and a data rate of 2 Mbps or even higher can be achieved over a carrier frequency of 20 MHz. (Abstract shortened by UMI.)...