Spiral-Shaped Piezoelectric MEMS Cantilever Array for Fully Implantable Hearing Systems

Abstract

Fully implantable, self-powered hearing aids with no external unit could significantly increase the life quality of patients suffering severe hearing loss. This highly demanding concept, however, requires a strongly miniaturized device which is fully implantable in the middle/inner ear and includes the following components: frequency selective microphone or accelerometer, energy harvesting device, speech processor, and cochlear multielectrode. Here we demonstrate a low volume, piezoelectric micro-electromechanical system (MEMS) cantilever array which is sensitive, even in the lower part of the voice frequency range (300–700 Hz). The test array consisting of 16 cantilevers has been fabricated by standard bulk micromachining using a Si-on-Insulator (SOI) wafer and aluminum nitride (AlN) as a complementary metal-oxide-semiconductor (CMOS) and biocompatible piezoelectric material. The low frequency and low device footprint are ensured by Archimedean spiral geometry and Si seismic mass. Experimentally detected resonance frequencies were validated by an analytical model. The generated open circuit voltage (3–10 mV) is sufficient for the direct analog conversion of the signals for cochlear multielectrode implants.

Low-Frequency Piezoelectric Accelerometer Array for Fully Implantable Cochlear Implants

“…The demonstrated test device (Figure 1) was fabricated by standard bulk micromachining techniques [3]. Archimedean spiral geometry ensures the reduced device footprint formed by deepreactive ion etching (DRIE).…”

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

“…Piezoelectric methods have been studied as middle ear and intracochlear implantations [21]. Multi-channel spiral-shaped AlN piezoelectric cantilever array was studied by Udvardi et al [22]. Lower frequency band (300-700 Hz) of the hearing spectrum is covered with 16 channels and they generate 3.0 -9.6 mV under 1 g acceleration.…”

Ultrasound‐Powered Implants: A Critical Review of Piezoelectric Material Selection and Applications

“…With the advances in material science, microfabrication, and low‐power electronics, the use‐cases, and capabilities for next‐generation IMDs are steadily rising and progressing in the direction of miniaturized, smart, and highly specific technologies. Recent technological upgrades to IMDs include pressure sensors in knee implants, [ 2 ] cardiac monitoring in pacemakers, [ 3 ] postsurgery infection monitoring in implants of a variety of types, [ 4,5 ] real‐time adjustments for electrical stimulation devices (closed‐loop), [ 6,7 ] fully implantable cochlear implants, [ 8 ] retinal implants, [ 9 ] and drug delivery systems. [ 10 ] Traditionally, electrically powered implants have been powered by batteries containing toxic materials, and occupy a large volume of the global implant volume, present environmental challenges, as well as limits the lifetime of the IMD.…”