Thin-Film PZT-Based Multi-Channel Acoustic MEMS Transducer for Cochlear Implant Applications

Abstract

This paper presents a multi-channel acoustic transducer that works within the audible frequency range (250-5500 Hz) and mimics the operation of the cochlea by filtering incoming sound. The transducer is composed of eight thin film piezoelectric cantilever beams with different resonance frequencies. The transducer is well suited to be implanted in middle ear cavity with an active volume of 5 mm × 5 mm × 0.62 mm and mass of 4.8 mg. Resonance frequencies and piezoelectric outputs of the beams are modeled with Finite Element Method (FEM). Vibration experiments showed that the transducer is capable of generating up to 139.36 mVpp under 0.1 g excitation. Test results are consistent with the FEM model on frequency (97%) and output voltage (89%) values. Device was further tested with acoustic excitation on an artificial tympanic membrane and flexible substrate. Under acoustic excitation, 50.7 mVpp output voltage generated under 100 dB Sound Pressure Level (SPL). Output voltages observed in acoustical and mechanical characterizations are the highest values reported to the best of our knowledge. Finally, to assess the feasibility of the transducer in daily sound levels, it was excited with a speech sample and output signal was recovered. Time-domain waveforms of the recorded and recovered signals showed close patterns.

Piezoelectric Multi‐Channel Bilayer Transducer for Sensing and Filtering Ossicular Vibration

“…Correlations between the input and output waveforms of the speech test also demonstrated that this approach could overcome the bottlenecks of the middle ear implantable sound detectors. [ 18 ] The sound detector presented in this study comprises the previous studies` outcomes and accommodates surgical operation methods. Available space in the middle ear could not be entirely utilized due to tissues, passing nerves, and long‐term patient health.…”

“…Our group has proposed a challenging approach to the self‐powered fully implantable cochlear implant concept. This concept, FLAMENCO: A Fully‐Implantable MEMS‐Based Autonomous Cochlear Implant, includes a multi‐channel acoustic transducer, [ 18 , 19 , 20 ] a piezoelectric energy harvester, [ 21 , 22 ] an interface circuit, [ 23 ] and a commercial cochlear electrode. [ 24 , 25 ] To comply with the FICI standards, the entire system can be implanted inside the middle ear cavity, collect the ambient sound by using the natural hearing mechanism, and filter the signal into frequency bands to stimulate the auditory nerves ( Figure 1 ).…”

Sensing Devices for Detecting and Processing Acoustic Signals in Healthcare

“…More recently, Yüksel et al presented a similar device that worked in a bandwidth between 0.2 and 5.5 kHz, with dimensions of 5 × 5 × 0.62 mm 3 ( Figure 7 ). Tests were only carried out on a testbench in the laboratory [ 65 ].…”

Electric-Force Conversion Performance of Si-Based LiNbO3 Devices Based on Four Cantilever Beams

“…The piezoelectric cantilever beams are critical in designing intelligent systems [1][2][3] as the primary structure of sensors. The cantilever beam structures [4], characterized by wide operating bandwidth, lightweight, powerful driving force, and high electromechanical conversion efficiency, have been used in the fields of micrometer/nanomechanical systems [5][6][7], server hard disk failure detection [8,9] and controller model validation [10,11].…”