Single Supply PWM Fully Implantable Cochlear Implant Interface Circuit with Active Charge Balancing

Yigit, H. Andac
Ulusan, Hasan
Koc, Mert
Yüksel, Muhammed Berat
Chamanian, Salar
Külah, Haluk
Low powered fully implantable cochlear implants (FICIs) untangle the aesthetic concerns and battery replacement problems of conventional cochlear implants. However, the reported FICIs lack proper charge balancing and require multiple external supplies to operate. In this work, a complete low power FICI interface circuit is designed that operates with a single supply and uses short-pulse-injection method for charge balancing. The system takes input from multi-channel piezoelectric transducers and stimulates the auditory neurons with pulse width modulated (PWM) output currents. By utilizing pulse width modulation technique with continuous interleaved sampling (CIS) sound processing strategy, a time gap is formed between two consecutive channels. Then, this gap is used for charge balancing operation. Overall power consumption of the low power FICI interface is decreased by clocked gated subthreshold amplifier and rectifier design. Furthermore, power efficient design of analog to digital converter (ADC) enhances the power reduction. The system is tested with an in-vitro test setup and it stimulates a single channel cochlear electrode with 50 dB input dynamic range while consuming $695~\mu \text{W}$ power from a single 1.8 V supply. The implemented FICI system can safely stimulate neurons for more than 18 days (with 16-hour daily operation) with an implantable 200 mWh battery without recharging. Furthermore, the short charge balance current pulses keep the electrode voltage difference after the stimulation within ±100 mV range, which ensures the residual charge is not hazardous for the auditory neurons.


Charge balanced neural stimulation interface circuit for fully implantable cochlear implants
Yiğit, Halil Andaç; Külah, Haluk; Department of Electrical and Electronics Engineering (2020)
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 circu...
MEMS thin film piezoelectric acoustic transducer for cochlear implant applications
İlik, Bedirhan; Külah, Haluk; Department of Electrical and Electronics Engineering (2018)
In this thesis, a multi-frequency thin film piezoelectric acoustic sensor concept to be placed on the eardrum has been proposed for the development of next generation and fully implantable cochlear implants (FICIs). The design consists of several thin film piezoelectric cantilever beams, each of which resonates at a specific frequency within the daily acoustic band. The device will exploit the functional parts of the natural hearing mechanism and mimic the function of the hair cells in the cochlea, where th...
Özbek, Abdurrahman Berkay; Külah, Haluk; Department of Electrical and Electronics Engineering (2021-12-17)
Cochlear implants are the most common treatment option for individuals with sensorineural hearing loss. However, despite the functional success, the patients have concerns about the aesthetics and practicality of the device. Fully implantable cochlear implants (FICI), on the other hand, have a promising future to overcome these drawbacks by replacing the external components with an acoustic sensor and interface electronics. To achieve a high quality of hearing, the interface electronics should effectively d...
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This paper presents an ultralow power interface circuit for a fully implantable cochlear implant (FICI) system that stimulates the auditory nerves inside cochlea. The input sound is detected with a multifrequency piezoelectric (PZT) sensor array, is signal-processed through a front-end circuit module, and is delivered to the nerves through current stimulation in proportion to the sound level. The front-end unit reduces the power dissipation by combining amplification and compression of the sensor output thr...
Citation Formats
H. A. Yigit, H. Ulusan, M. Koc, M. B. Yüksel, S. Chamanian, and H. Külah, “Single Supply PWM Fully Implantable Cochlear Implant Interface Circuit with Active Charge Balancing,” IEEE Access, pp. 52642–52653, 2021, Accessed: 00, 2021. [Online]. Available: