Piezoelectric Cupular Micro Transducer Implant

Vestibular Hair Cells

Vestibular Hair Cell Damage

Hair Cell Damage

Damage can cause hair cells to no longer stand up & reduce/diminish signal

sent to brain

Vestibular Ototoxicity

Balance Disorders

Our Solution: Device that replaces damaged hair cells & sense fluid flow in the vestibular

area to send signals to the brain to adjust balance

Healthy Hair Cells

Microtransducer location

The Cupula

Proposed Solution

● Thin film piezoelectric MEMS device implanted on cupula

● Fills role of damaged hair cells● Cantilever beams extend, transducing stress

into electrical signal to vestibular nerve

Large-scale model of proposed cantilever device lodged on cupula and exposed in endolymph.

● Converting mechanical stress to an electrical signal

● Direct piezoelectric effect○ Voltage generated across

material from tensile or compressive stress

○ Proportional via piezoelectric constant

Cantilever Mechanotransduction

Fabrication1. Construct “hair cell” cantilever beams as per Ilik et al.

a. Thin Film Piezoelectric Transducer (6 mask)

b. Patterned using RIE and cantilever formed with DRIE

2. Connect to single-supply micro-sized voltage-to-current

OpAmp

● Parylene C coating○ Flexible○ Biocompatible○ Protects electrical connections

● Cautions○ Silicon foreign body response shown in

cochlear implants○ Calcium Carbonate crystal interference

■ Symptom of Benign Paroxysmal Positional Vertigo (BPPV)

Biocompatibility

Pre-clinical:

● Animal testing: chinchillas○ Evaluate animals with vestibular hair cell

loss, control group and group with implanted device on balance pre- and post-implantation

TestingBenchtop:

● Affirm voltage sensitivity and accuracy as a function of cantilever displacement

● Biomimetic semicircular canal model: affirm correct signal transduction with additive effects of 3 semicircular canals

● Difficult to replace or remove a broken device ● Voltage-to-current transduction requires

uninterrupted battery supply● Sensitivity vs. size trade-off--higher number of

smaller cantilevers is more sensitive, but more difficult to manufacture

Limitations

Haybach, P., RN, MS. (2015, December 29). Ototoxicity. Retrieved from https://vestibular.org/ototoxicity

Anatomy and Physiology Chapter 8: The Nervous System - Hearing and Equilibrium. Lumen Learning. Retrieved from https://courses.lumenlearning.com/nemcc-ap/chapter/special-senses-hearing-audition-and-balance/

Angelaki, D. & Dickman, J. D.. “The vestibular system.” In R. Biswas-Diener & E. Diener (Eds), Noba textbook series: Psychology. 2019. Champaign, IL nobaproject.com

Ilik, B., Koyuncuoglu, A., Sardon-Sukas, O., Kulah, H. “Thin film piezoelectric acoustic transducer for fully implantable cochlear implants” Sensors and Actuators A: Physical. Sep. 2018. Vol. 280, pp. 38-46.

Della Santina, C., Migliaccio, A., Patel, A. “Electrical Stimulation to Restore Vestibular Function--Development of a 3D Vestibular Prosthesis.” Conf. Proc. IEEE Eng Med Biol Soc. Oct. 2009. Vol 7, pp. 7380-7385.

O'Malley, Jennifer T, et al. “Foreign Body Response to Silicone in Cochlear Implant Electrodes in the Human.” Otology & Neurotology : Official Publication of the American Otological Society, American Neurotology

Society [and] European Academy of Otology and Neurotology, U.S. National Library of Medicine, Aug. 2017

References