Measurement of inhomogeneous ion flow fields using glass micro-electrodes and development of micro-ion chromatography

2020 Fiscal Year Final Research Report

• Project/Area Number: 18H01372
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 19010:Fluid engineering-related
• Research Institution: Toyohashi University of Technology (2020); Osaka University (2018-2019)
• Principal Investigator: Doi Kentaro 豊橋技術科学大学, 工学(系)研究科(研究院), 教授 (20378798)
• Co-Investigator(Kenkyū-buntansha): 川野 聡恭 大阪大学, 基礎工学研究科, 教授 (00250837)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 分子流体力学 / マイクロ・ナノ工学 / イオン電流 / イオンクロマトグラフィ

Outline of Final Research Achievements

In this study, focusing on the transport phenomena of nanoparticles and ions in micro- and nanometer spaces, we developed a novel technique for measuring local concentration fields and electric fields. Electric potential distributions in the liquid were clarified by scanning a glass micro-electrode with a tip diameter of about 500 nm using a fluidic channel with an orifice, and the conductivity was derived from the current-voltage characteristics to determine the electrolyte concentrations. As a result of quantitative evaluations, we confirmed that the concentration could be measured with an accuracy of 10% or less, and established an absolute concentration measurement method that did not require calibration using standard solutions. Furthermore, it was shown that pH could be measured by using a double-barreled microelectrode, and that the proton concentration could be measured in a wide range of acid and alkaline solutions.

Free Research Field

分子流体力学

Academic Significance and Societal Importance of the Research Achievements

マイクロ・ナノメートルスケールの微小空間におけるナノ粒子やイオン輸送現象について，力学的観点から現象を解明し，さらには局所的な電場や濃度場の測定技術を確立した．従来の導電率や濃度測定法では，標準液を用いた校正が必要であるが，ここで開発した手法は，液中の局所的な電場を直接的に測定することから，校正を必要とすることなく濃度を評価することが可能である．液中の電場と濃度場が明らかにされたことから，電気流体力学現象等に関する場の定量評価へと発展することが期待される．