Design of a Bone-Guided Cochlear Implant Microsystem With Monopolar Biphasic Multiple Stimulations and Evoked Compound Action Potential Acquisition and Its <italic>In Vivo</italic> Verification

A CMOS bone-guided cochlear implant (BGCI) microsystem is proposed and verified. In the implanted System on Chip (SoC) of the proposed BGCI, the evoked compound action potential (ECAP) acquisition and electrode–tissue impedance measurement (EAEIM) circuit is integrated to measure both ECAP and electrode–tissue impedance for clinical diagnoses. Both positive-/negative-voltage charge pumps and monopolar biphasic constant-current stimulation (CCS) stimulator are designed on-chip to realize monopolar biphasic CCS or double-electrode multiple stimulations with a maximum stimulation current of 1.2 mA and a step of 10 μA. With the double-electrode multiple stimulations, the electric field can be shifted and localized under the stimulating electrode to stimulate the auditory nerves. The wireless bilateral data telemetry circuits with a full-wave active rectifier and the pulsed load-shift keying (PLSK) modulators/demodulators are designed for power and Manuscript received January 11, 2021; revised April 21, 2021; accepted June 1, 2021. Date of publication June 21, 2021; date of current version September 24, 2021. This article was approved by Associate Editor Jun Deguchi. This work was supported in part by the Center for Neuromodulation Medical Electronics Systems from The Featured Areas Research Center Program within the framework of the Higher Education Sprout Project by the Ministry of Education (MOE) in Taiwan and in part by the Ministry of Science and Technology (MOST), Taiwan, under Project MOST-108-2321-B009-007-MY2. (Corresponding authors: Chung-Yu Wu; Chia-Fone Lee.) This work involved human subjects or animals in its research. Approval of all ethical and experimental procedures and protocols was granted by the National Taiwan University College of Medicine and College of Public Health Institutional Animal Care and Use Committee (IACUC) under Application No. 20180318. Sung-Hao Wang, Yu-Kai Huang, Ching-Yuan Chen, Li-Yang Tang, Chung-Chih Hung, Ming-Dou Ker, and Chung-Yu Wu are with the Department of Electronics Engineering, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan, and also with the Institute of Electronics, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan (e-mail: peterwu@mail.nctu.edu.tw). Yen-Fu Tu and Chia-Hsiang Yang are with the Graduate Institute of Electronics Engineering, National Taiwan University, Taipei 10617, Taiwan. Po-Chih Chang and Chien-Hao Liu are with the Mechanical Engineering Department, National Taiwan University, Taipei 10617, Taiwan. Chia-Fone Lee is with the Department of Otolaryngology, Hualian Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Hualien 970, Taiwan, and also with the Department of Otolaryngology Head and Neck Surgery, School of Medicine, Tzu Chi University, Hualien 970, Taiwan (e-mail: e430013@yahoo.com.tw). Color versions of one or more figures in this article are available at https://doi.org/10.1109/JSSC.2021. 3087629. Digital Object Identifier 10.1109/JSSC.2021. 3087629 data transmission. In vivo animal tests on guinea pigs have shown that the Wave III of electrically evoked auditory brainstem responses (EABRs) can be evoked successfully by electrical stimulation. Moreover, the decreasing latency gradient of evoked Wave III has been measured under the double-electrode multiple stimulations where the location of peak electric field can be shifted to the stimulating electrode in the apical site to stimulate the auditory nerves. Thus, the desired frequency resolution and spatial specificity of stimulation can be achieved. Both electrical measurement and in vivo animal tests have verified that the proposed BGCI microsystem is a feasible solution to eliminate the symptoms for patients with high-frequency hearing loss.