A tri-coil bellows-type round window transducer with improved frequency characteristics for middle-ear implants.
A number of methods to drive the round window (RW) using a floating mass transducer (FMT) have been reported. This method has attracted attention because the FMT is relatively easy to implant in the RW niche. However, the use of an FMT to drive the RW has been proven to produce low outputs at frequencies below approximately 1 kHz. In this study, a new tri-coil bellows-type transducer (TCBT), which has excellent low frequency output and is easy to implant, is proposed. To design the frequency characteristics of the TCBT, mechanical and electrical simulations were performed, and then a comparative analysis was conducted between a floating mass type transducer (like the FMT) and a fixed type transducer (like the TCBT). The features of the proposed TCBT are as follows. First, the TCBT's housing is fixed to the RW niche so that it does not vibrate. Second, the internal end of a tiny bellows is connected to a vibrating three-pole permanent magnet located within three field coils. Finally, the rim of the bellows bottom is attached to the end of the housing that hermetically encloses the three field coils. In this design, the only vibrating element is the bellows itself, which efficiently drives the RW membrane. To evaluate the characteristics of this newly developed TCBT, the transducer was installed in the RW niche of temporal bones and the velocity of the stapes was measured using a laser Doppler vibrometer. The experimental results indicate that the TCBT can produce 100, 111, and 129 dB SPL equivalent pressure outputs at below 1 kHz, 1-3 kHz, and above 3 kHz, respectively. Thus, the TCBT with one side coupled to the RW via a bellows will be easy to implant and offer better performance than an FMT.
School of Electronics Engineering, College of IT Engineering, Kyungpook National University, 80 Daehak-ro, Buk-gu, Daegu, Republic of Korea. Electronic address: swap9552@naver.com.
Dong Ho
DH
Shin
Department of Biomedical Engineering, Kyungpook National University Hospital, 130 Dongdeok-ro, Jung-gu, Daegu, Republic of Korea. Electronic address: seongkw@ee.knu.ac.kr.
Ki Woong
KW
Seong
Department of Mechanical Engineering, Stanford University, 496 Lomita Mall, CA, 94305, USA. Electronic address: puria@stanford.edu.
Sunil
S
Puria
Department of Otorhinolaryngology-Head and Neck Surgery, School of Medicine, Kyungpook National University, 680 Gukchaebosang-ro, Jung-gu, Daegu, Republic of Korea. Electronic address: kylee@knu.ac.kr.
Kyu-Yup
KY
Lee
School of Electronics Engineering, College of IT Engineering, Kyungpook National University, 80 Daehak-ro, Buk-gu, Daegu, Republic of Korea. Electronic address: jhcho@ee.knu.ac.kr.
Jin-Ho
JH
Cho
D000161:Acoustic Stimulation; D000328:Adult; D000368:Aged; D002102:Cadaver; D002138:Calibration; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009998:Ossicular Prosthesis; D012405:Round Window, Ear / Q000601:surgery*; D013199:Stapes / Q000502:physiology; D013701:Temporal Bone / Q000502:physiology* / Q000601:surgery; D014159:Transducers; D014732:Vibration
Middle-ear implants; Round window (RW); Tri-coil bellows-type transducer (TCBT)