2020 Fiscal Year Research-status Report
Metallo-Dielectric Janus Particles as Building Blocks for Designer Active Materials
| Project/Area Number |
20K03786
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| Research Institution | Kyoto University |
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Principal Investigator |
MOLINA JOHN 京都大学, 工学研究科, 助教 (20727581)
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| Project Period (FY) |
2020-04-01 – 2023-03-31
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| Keywords | Active janus particles / Induced charge / Electrophoresis |
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| Outline of Annual Research Achievements |
First, we have participated in the publication of an extensive review article, recently published in Soft Matter, on the direct numerical simulation of hydrodynamically interacting particles. This paper is the culmination of close to two decades of work in our lab, of which I have been an active participant since 2011. Besides detailing our work on active-matter, and swimming particles in particular, it has also introduced recent developments, such phase-separating and non-Newtonian fluids, which we will be able to use within our study of Janus particles.
We have performed extensive simulations to investigate the velocity reversal of Induced Charge Electrophoretic (ICEP) Janus particles reported experimentally (for high enough frequencies of the external electric field). This work was carried out as part of a Master thesis, under my supervision. We have found good agreement with theory and experiments. In particular, we reproduced the velocity reversal at high frequencies, even in the absence of a conducting wall. Preliminary simulations for two-particle systems show a frequency regime in which inter-particle interactions are attractive, which could lead to the formation of active chains that has been reported experimentally.
Finally, in collaboration with a post-doc in our group, we have investigated the dynamics of chiral swimmers near boundaries, which could eventually be of use for our study on the ICEP Janus particles.
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| Current Status of Research Progress |
Current Status of Research Progress
3: Progress in research has been slightly delayed.
Reason
We have reproduced the velocity reversal observed experimentally, but we have not yet developed a satisfactory explanation for this behavior (though there seems to be a clear correlation with the asymmetric charge distribution and electric field around the particle). Furthermore, we need to include a more realistic model for the frequency dependent material properties, i.e., the permittivity and conductivity (so far we have considered them as constant).
We have extended our prototype Python code to 3D, but incorporating the Janus functionality into the KAPSEL code base is taking more time than initially planned.
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| Strategy for Future Research Activity |
We will continue our investigation of the velocity reversal, in order to elucidate the physical mechanism that is responsible for this behavior. We will finish implementing the Janus functionality into the Kapsel code base, in order to investigate the dynamics of many-particle active systems.
In parallel, and as a contingency, we will also work on optimizing our Python code, in order to reduce the cost of 3D systems. Previous experience with such simulations has shown that it is possible to have Python within a factor of 2 of C/C++ code. At this level, it would be possible to perform most of the simulations that we have planned using the Python code, which is much easier to maintain and modify than its C/C++ counterpart.
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| Causes of Carryover |
The ongoing COVID-19 outbreak has dramatically altered our original plans, particularly with regards to travel and conference participation. We plan to use these funds in the next fiscal year for open access article publication fees and, if possible, domestic travel fees.
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Research Products
(6 results)
