Formation, encapsulation, and validation of membrane-based artificial hair cell sensors

Abstract

Hair cell structures are one of the most common forms of sensing elements found in nature. In nearly all vertebrates hair cells are used for auditory and vestibular sensing. In humans, approximately 16,000 auditory hair cells can be found in the cochlea of the ear. Each hair cell contains a stereocilia, which is the primary structure for sound transduction. This study looks to develop and characterize an artificial hair cell that resembles the stereocilia of the human ear. Recently our research group has shown that a single artificial hair cell can be formed in an open substrate using a single aqueous droplet and a hydrogel. In this study, air was blown across the hair and analyzed using spectral analysis. The results of this study provided the foundation for our current work toward an artificial hair cell that uses two aqueous droplets. In the current study a test fixture was created in order to consistently measure various properties of the encapsulated hair cell. The response of the hair cell was measured with an impulse input at various locations on the test fixture. A frequency response function was then created using the impulse input and the output of the sensor. It was found that the vibration of the hair was only detectable if the test fixture was struck at the correct location. By changing the physical parameters of the hair sensor, such as hair length, we were able to alter the response of the sensor. It was also found that the sensitivity of the sensor was reliant on the size of the lipid bilayer.

Biomolecular hydrogel-based lipid bilayer array system

“…This technique is successfully used to produce relatively durable and packaged biomolecular material assemblies capable of being transported, handled, and shaken. 9,10 In parallel, the use of hydrogels as a solid aqueous phase has been considered as an alternative to the liquid phase. Lipid bilayer interfaces, successfully formed in a solidified aqueous environment, exhibited high electrical resistances which enabled single-channel recordings of channels made from alamethicin peptides.…”

Airflow Sensing With Arrays of Hydrogel Supported Artificial Hair Cells

“…A hydrogel "follicle" served as both a rigid support for the hair and as a hydrophilic scaffold on which to form the lipid bilayer. Subsequent designs have subjected the sensor to various types of excitation: continuous air and water flow [61,79], impact hammer [80], mechanical perturbation [81,82] and oscillating fluid flow [83]. These studies validated the functionality of membrane-based AHCs in various conditions, yet a detailed understanding of their dynamic behavior has proved challenging largely due to high variability in bilayer, hair and hydrogel properties.…”