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Title: Novel telemetry system for closed loop vestibular prosthesis
Author: Cirmirakis, D.
Awarding Body: University College London (University of London)
Current Institution: University College London (University of London)
Date of Award: 2013
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Disorders of the vestibular system result in loss of body balance and a steady vision in humans and animals. The most common consequences include vertigo, oscillopsia, postural instability and blurred vision. Currently, conventional medicine cannot cure the damage or restore the function of the vestibular system. Vestibular prosthesis may assist in restoring its function using electrical stimulation, which involves delivering current pulses into the nerves innervating the semi-circular canals in the inner ear. A vestibular prosthesis contains external electronics and an implantable medical device . The system delivers modulated electrical pulses and stimulates vestibular nerves with these pulses to inform the brain about the motion. Power transfer to, and communication with the implanted device, is provided by telemetry. In biomedical implanted devices the telemetry is usually implemented by radio-frequency induction using weakly coupled coils. Using a single set of coils for simultaneous power transfer and communication creates the challenge of contradicting requirements. For high data rates the inductive link must have a wide bandwidth but power transfer requires a low bandwidth. Moreover by modulating a carrier the power transfer is degraded. This thesis describes the design, implementation and experimental evaluation of a novel telemetry system for a three-dimensional vestibular prosthesis with neural recording. The developed telemetry system uses a single pair of inductively-coupled coils to power-up the implant and maintain bi-directional communication to control its operation. It also relays raw electroneurogram (ENG) data out of the body at high speed. For inductive power control two methods are combined: a geometrical approach and a feedback loop to maintain a constant level of delivered power. The communication to the implant (downlink) is obtained by amplitude modulation while the communication from the implant to the external transmitter (uplink) uses passive phase shift modulation. On-chip humidity sensing capabilities are facilitated in the implant microelectronics to monitor hermeticity of the package. The uplink achieves the highest data speed demonstrated in the literature of available methods using a single set of coils with combined power and communication links. The developed technique can be applied to other applications including RFID.
Supervisor: Demosthenous, A. ; Donaldson, N. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available