EAPSI: Development of novel silicon microchamber to investigate mechanical and electrical properties of cochlear structures

Marnell Daniel J, Rochester NY

Investigators

Abstract

The primary function of the mammalian cochlea is to provide the brain with information about the acoustic environment - specifically, it decodes with a high degree of precision information about the frequency and intensity of incoming sounds. As a result, how the cochlea is able to achieve such remarkable frequency selectivity and high sensitivity has been a hot topic in hearing research. In order to better study how the cochlea functions, a novel microfluidic device will be developed and fabricated under the expertise of Dr. Yong-Jin Yoon at Nanyang Technological University in Singapore. The creation of a device that imitates several features of the cochlea will allow us to better identify the operating principles of the mammalian cochlea, and make contributions not only to the field of hearing research, but also the field of mechano-transduction in general. According to the prevalent theory, the cochlea achieves frequency selectivity through mechanical resonance of a central partition that holds the sensory epithelium. However, experimental ground supporting this theory is weak, and existing measurements of the mechanical properties of the cochlear partition still do not provide clear evidence for this theory. For example, previous measurements of cochlear partition stiffness are measured using point force, rather than the more physiologically relevant form of fluid pressure. In an effort to overcome this problem, a microfluidic chamber that imitates the cochlear compartments will be developed. This microchamber will allow to place excised sections of the cochlear partition from an animal model in an environment that is physiologically, mechanically, and electrically similar to its in vivo state. The excised section of the cochlear partition is then stimulated with fluid pressure, and nanoscale measurements of the tissue displacement in all three dimensions are recorded. A previous design of the microchamber was fabricated using stereolithography, but calibration of electromechanical stimuli has proven to be difficult. To overcome the limitations of the current design, a new silicon-chip version of the microchamber will be designed and fabricated using standard microfabrication techniques. This technology will allow to add features such as an embedded pressure transducer for the calibration of fluid pressure applied to tissue specimens. This NSF EAPSI award is funded in collaboration with the National Research Foundation of Singapore.