title: A Fully-Implantable Cochlear Implant SoC with Piezoelectric Middle-Ear Sensor and Arbitrary Waveform Neural Stimulation.
abstract: A system-on-chip for an invisible, fully-implantable cochlear implant is presented. Implantable acoustic sensing is achieved by interfacing the SoC to a piezoelectric sensor that detects the sound-induced motion of the middle ear. Measurements from human cadaveric ears demonstrate that the sensor can detect sounds between 40 and 90 dB SPL over the speech bandwidth. A highly-reconfigurable digital sound processor enables system power scalability by reconfiguring the number of channels, and provides programmable features to enable a patient-specific fit. A mixed-signal arbitrary waveform neural stimulator enables energy-optimal stimulation pulses to be delivered to the auditory nerve. The energy-optimal waveform is validated within-vivomeasurements from four human subjects which show a 15% to 35% energy saving over the conventional rectangular waveform. Prototyped in a 0.18μm high-voltage CMOS technology, the SoC in 8-channel mode consumes 572μW of power including stimulation. The SoC integrates implantable acoustic sensing, sound processing, and neural stimulation on one chip to minimize the implant size, and proof-of-concept is demonstrated with measurements from a human cadaver ear.
authors.affiliation: Microsystems Technology Laboratories, Massachusetts Institute of Technology, Cambridge, MA 02139 USA.
authors.forename: Marcus
authors.initials: M
authors.lastname: Yip
authors.affiliation: Microsystems Technology Laboratories, Massachusetts Institute of Technology, Cambridge, MA 02139 USA.
authors.forename: Rui
authors.initials: R
authors.lastname: Jin
authors.affiliation: Harvard Medical School, Boston, MA 02115 USA, and Massachusetts Eye and Ear Infimary, Boston, MA 02114 USA.
authors.forename: Hideko Heidi
authors.initials: HH
authors.lastname: Nakajima
authors.affiliation: Harvard Medical School, Boston, MA 02115 USA, and Massachusetts Eye and Ear Infimary, Boston, MA 02114 USA.
authors.forename: Konstantina M
authors.initials: KM
authors.lastname: Stankovic
authors.affiliation: Microsystems Technology Laboratories, Massachusetts Institute of Technology, Cambridge, MA 02139 USA.
authors.forename: Anantha P
authors.initials: AP
authors.lastname: Chandrakasan
keywords: Arbitrary waveform; SoC; cochlear implant; energy-efficient; hearing loss; implantable; low-voltage; microphone; middle ear; piezoelectric; reconfigurable; stimulation; ultra-low-power