2022 Fiscal Year Annual Research Report
Development of Nanofluidic Thermoelectric Devices Using Two-Dimensional Materials
| Project/Area Number |
22H01410
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| Allocation Type | Single-year Grants |
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| Research Institution | The University of Tokyo |
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Principal Investigator |
徐 偉倫 東京大学, 大学院工学系研究科(工学部), 准教授 (50771549)
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| Co-Investigator(Kenkyū-buntansha) |
大宮司 啓文 東京大学, 大学院工学系研究科(工学部), 教授 (10302754)
江草 大佑 東京大学, 大学院工学系研究科(工学部), 助教 (80815944)
シャミン ジョバイル 東京大学, 大学院工学系研究科(工学部), 特任助教 (00933988)
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| Project Period (FY) |
2022-04-01 – 2026-03-31
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| Keywords | Nanopore / Two-dimensional material / Ion transport / Nnanofabrication |
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| Outline of Annual Research Achievements |
We have solidified the core technique for nanopore fabrication on suspended two-dimensional materials under transmission electron microscopy. Specifically, we demonstrated pore milling from sub-nanometer to 5 nanometers, showing the controllability of the pore dimension. A multiple drilling process is proposed and tested showing outstanding spacial resolution. For each drilling the pore size can be controlled within one nanometer. By repeating the process at slightly different locations, the desired pore shape can be precisely sculpted. Using this method, we have created sub-5 nanometer pores with high circularity. In the meanwhile, we have constructed the flow system for ionic current measurements through nanopore chips, temperature controllers for heat source and purchased current meters for thermoelectric evaluations. The temperature in the reservoirs separated by the nanopore membrane can be precisely controlled. On the other hand, a theoretical model based on the Poisson-Nernst-Planck and Navier-Stokes equations has been constructed to predict thermoelectric performance of our system. It is shown that the power density reaches the maximum as the characteristic electric double layer thickness becomes close to the pore radius. This will guide our experimental design by selecting suitable solution conditions.
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| Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
The project is accelerated via abundant collaboration. We obtained large area high-quality monolayer molybdenum disulfide from our collaborators at the University of Tokyo facilitating the development processes. In addition, we received tremendous support from our external collaborators at Osaka University in terms of nanopore fabrication and lithography methods. On top of these, the teamwork and outstanding graduate students in our lab greatly enhanced the research progress.
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| Strategy for Future Research Activity |
There are two main directions proceeding in parallel: (i) fabrication of nanopore array on two-dimensional materials and (ii) selection of the optimal two-dimensional material for thermoelectric application. The first point is considered as a critical process for scaling up, given that the single pore conductance can largely reduce as the pore number increases due to the pore-pore interaction. Therefore, the arrangement and optimum of the pores will be focused. Secondly, the surface charge and hydrophobicity properties, which are subject to the interaction and reactions between the two-dimensional material and water molecules, remarkably affect the ion transport in nanopores. The selection of two-dimensional materials with both high pore conductance and mechanical strength is crucial.
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