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Charge balanced neural stimulation interface circuit for fully implantable cochlear implants

2020
Yiğit, Halil Andaç
Cochlear implants (CI) are the most successful prosthesis, which helps people suffering from profound deafness; however, aesthetic concerns and daily battery replacement are the main problems. These problems can be solved by a low power fully implantable cochlear implant (FICI). The FICI system should operate with ultra-low power consumption while covering high input dynamic range. Moreover. the system should ensure safe stimulation with single battery usage. In this thesis, a low power FICI interface circuit is designed while focusing on the charge balanced stimulation and single supply implantation. The interface circuit takes input from multi-channel piezoelectric transducers and stimulates the electrodes with pulse width modulated output currents. By pulse width modulation, a time gap is formed between two consecutive channels, and this gap is used for charge balancing operation. The system is tested with an in-vitro test setup and it safely stimulates the single channel cochlear electrode with 50 dB input dynamic range while consuming lower than 800 μW power from a single 1.8 V supply