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

哺乳动物耳蜗的主要功能是为大脑提供有关声学环境的信息-具体而言，它以高精度解码有关传入声音的频率和强度的信息。因此，耳蜗如何能够获得如此显著的频率选择性和高灵敏度一直是听觉研究的热点。为了更好地研究耳蜗的功能，新加坡南洋理工大学的Yong-Jin Yoon博士将开发和制造一种新型的微流体装置。创建一个设备，模仿耳蜗的几个功能，将使我们能够更好地识别哺乳动物耳蜗的工作原理，并作出贡献，不仅在听力研究领域，而且在一般的机械转导领域。根据流行的理论，耳蜗通过保持感觉上皮的中央分区的机械共振来实现频率选择性。然而，支持这一理论的实验基础是薄弱的，现有的耳蜗分区的机械性能的测量仍然没有提供明确的证据，这一理论。例如，耳蜗分区刚度的先前测量是使用点力来测量的，而不是生理上更相关的流体压力形式。为了克服这个问题，将开发一种模仿耳蜗隔室的微流体室。该微室将允许将来自动物模型的耳蜗分区的切除部分放置在生理学、机械学和电学上与其体内状态相似的环境中。然后用流体压力刺激耳蜗分区的切除部分，并记录所有三个维度的组织位移的纳米级测量值。以前的设计的微室制造使用立体光刻，但机电刺激的校准已被证明是困难的。为了克服目前设计的局限性，将使用标准的微加工技术设计和制造一种新的硅芯片版本的微室。该技术将允许添加诸如嵌入式压力传感器的功能，用于校准施加到组织样本的流体压力。这个NSF EAPSI奖是与新加坡国家研究基金会合作资助的。

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.