In situ scanning electron microscopy observations of filler material transport in branched carbon microtubes by Joule heating
| Autor: | Hideo Kohno, Daiya Sasaki, Masaki Okada |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Materials science
Vapor pressure Scanning electron microscope chemistry.chemical_element 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Electromigration 0104 chemical sciences Temperature gradient chemistry Structural Biology Radiology Nuclear Medicine and imaging Electric current Composite material 0210 nano-technology Joule heating Instrumentation Carbon Voltage |
| Zdroj: | Microscopy. 69:291-297 |
| ISSN: | 2050-5701 |
| DOI: | 10.1093/jmicro/dfaa023 |
| Popis: | Y-branched or side-by-side-branched carbon microtubes with metal filler material were fabricated, and material transport in the branched microtubes with Joule heating was investigated using in situ scanning electron microscopy with micro-electrode probes. When a voltage and electric current were applied, the material enclosed in the microtubes moved from its original position. The movement was not related to the direction of the electric current; therefore, it is concluded that the movement was not due to electromigration, but rather a temperature gradient, volume expansion and increased vapor pressure by Joule heating. In Y-branched microtubes, a part of the metal filler material moved from one branch to another branch, which would be useful for microfluidic flow switching. A cylindrical filler material was also observed to be expelled from a branch while its shape was maintained, and this phenomenon is presumably caused by vaporization-induced high pressure and could find application in micro-mechanical manipulators such as punching needles. In side-by-side-branched carbon microtubes, Joule heating caused thermal volume expansion to fill the spaces in the branches that were initially empty. The microtubes then reverted to a state almost identical to the initial state with empty spaces when the electric current was turned off. These results suggest that thermal volume expansion could be employed for flow switching. |
| Databáze: | OpenAIRE |
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