| 研究実績の概要 |
In the previous year, we constructed a new experimental setup for hydrophone sensing of bubble dynamics inside solid state nanopores. The effect of pore diameters, bias voltages and dissolved gas on the resulting bubble dynamics were captured. Three types of bubble nucleations were observed: homogeneous bubbles forming at the pore center and patch heterogenous bubbles nucleating on the pore walls. For pore diameters smaller than 500 nm, the patch heterogeneous bubbles sometimes coalesced to form a annular or film bubble which due to the cylindrical shape of the pore resembled the shape of a torus. Under continuous Joule heating, the torus bubble oscillated volumetrically in the megahertz range. Using theoretical modelling and computer simulations, the equilibrium size, temperature and stability of the bubble was established. Finally, a boiling curve showing the distinct boiling zones and transition points was constructed based on the current signals. The results of homogenous bubble growth and collapse dynamics and nucleate to film boiling transition within nanopores are being summarized for two separate journal papers. In another research topic, we performed statistical analysis of current signals for sequential bubble generation inside nanopore. Using histogram segregation and machine learning, signal features for homogeneous and patch heterogeneous bubbles were segregated. This research was presented at the IEEE-NEMS 2022 conference.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
1: 当初の計画以上に進展している
理由
Our goal for 2021 was to establish an experimental setup for acoustic sensing of nanopore nanobubbles. We were able to meet this target and also gather sufficient results for two journal papers. Moreover, we now have a comprehensive understanding of the different boiling regimes inside nanopore. Additionally, theoretical models explaining the results have also been developed within the short time frame of one year. We have also performed for the first time, machine learning analysis of bubble nucleation classification, which we have termed as 'bubble informatics'.
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| 今後の研究の推進方策 |
For this fiscal year I plan to implement these targets:
(i) Experimental study and theoretical modelling of nucleate and film boiling transition mechanism and its hysteresis within cylindrical nanopores. A journal paper on boiling transition and boiling curve inside nanopore would be summarized.
(ii) Using a two hydrophone setup, a new experimental setup would be used to quantify bubble translation within nanopores due to
electric field force.
(iii) Using both resistive pulse sensing and acoustic signals, machine learning model would be updated for big data analysis of sequential nanopore bubble generation.
(v) These results would be presented at American Physical Society (Division of Fluid Dynamics) 2022.
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