| dc.description.abstract | Abstract
Functional Neuromuscular Stimulation plays an important role in the treatment of nervous diseases and rehabilitation of nerve injury. With the rapid development of microelectronic technology, bio-technology and Neuroscience, Functional Neuromuscular Stimulation has been transformed from a traditional electrical stimulation to implantable electrical stimulation, and got great progress in Parkinson, Epilepsy, Chronic Pain and others visual diseases.
This thesis aims to design an electrical stimulator controller for implanted visual prosthesis. The designed electrical stimulator stimulates nerves or muscles using electrodes as the interface. Generally the impedance of electrode-tissue interface may change in the rage of 10KΩ – 100KΩ due to electrode itself such as poor contact, the electrode size, material differences, and stimulus current and environmental factors. It is necessary to adjust the stimulus period to get correct electrical charge, otherwise, will induce the difference between theoretical electrical charge and real electrical charge, and sometimes will damage the cell permanently.
This thesis proposes a new impedance measurement circuit called PWM-based auto-tuning electrical charge timing controller, ahead of the stimulation circuit, to prevent inaccurate electrical charge and protect histiocyte. The width of the digital pulse width modulator can be varied automatically, based on different interface impedances. That means the stimulus period can be auto-adjusted with dynamic impedance to get required electrical charge and best effect.
Besides, the electrical stimulator is designed by a high voltage output driver which can generate three times supply voltage output. The whole design is implemented in TSMC 0.18-μm standard CMOS technology to demonstrate the feasibility of the proposed electrical stimulator. An advantage is that it can be fully integrated with other circuits without extra processing costs.
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