基于石墨烯谐振器的纳米孔气体输运研究

小尺度下气体输运蕴含着丰富的信息，对气体阻尼、散热、气体通量和选择性等都有着重要影响。随着微纳系统尺寸缩小到纳米级，纳维-斯托克斯连续性方程逐渐被分子流理论取代，气体输运从连续介质区到过渡流区最终到分子流区。由于材料和实验条件的限制，分子流区的研究主要以理论模拟为主。石墨烯单原子层薄且机械化学性能稳定，是研究分子流区的理想材料。理论研究表明石墨烯纳米孔分子流区包括两种路径：直接扩散路径和表面扩散路径。但至今没有相关实验系统地研究石墨烯纳米孔上分子流机理。本项目将从实验上对石墨烯机械谐振器中的纳米孔气体分子输运进行详细的研究。研究内容包括：1）纳米孔石墨烯鼓膜谐振器的设计与加工；2）利用温度、电及官能团修饰等调控手段探索气体分子通过纳米孔时不同的输运机理；3）实现可控分子筛分。本研究将为高灵敏度和多气体检测的气体微纳流体器件和高选择性高通量的高效分离膜打下基础。

In microscale, the transport of gas molecules are closely related to gas damping, heat dissipation, gas permeance and selectivity. Once MEMS/NEMS reach nanoscale (~1 nanometer), the continuum Navier-Stokes equations are substituted by molecular transport theories, where the gas transport changes from convective flow regime to intermediate regime to Knudsen flow regime. Limited by the materials and experimental conditions, the studies of gas molecule transport have been mainly done by theories and simulations. Graphene is an ideal material for studying the transport mechanisms of gas molecules due to its atomic thickness, robustness and excellent chemical resistance. And yet, there is no systematically experimental study of gas transport through nanoporous graphene. Here, we take advantage of graphene mechanical resonators to study the gas molecule transport mechanisms thorough nanopores. The study includes: 1) The design and fabrication of the nanoporous-graphene-membrane resonators; 2) Studying the transport mechanisms of gas molecules through nanopores via tuning temperatures, voltages and functionalization groups; 3) Achieving controllable molecular sieving. This study will shed light on the multi-gas sensing with ultrahigh sensitivity and efficient gas separations with both high selectivity and high permeance.