The electromembrane process, which has advantages such as scalability, sustainability, and eco-friendliness, is used in renewable energy fields such as fuel cells and reverse electrodialysis power generation. Most of the research to visualize the internal flow in the electromembrane process has mainly been conducted on heterogeneous ion exchange membranes, because of the non-uniform swelling characteristics of the homogeneous membrane. In this study, we successfully visualize the electroconvective vortices near the Nafion homogeneous membrane in PDMS-based microfluidic devices. To reinforce the mechanical rigidity and minimize the non-uniform swelling characteristics of the homogeneous membrane, a newly developed swelling supporter was additionally adapted to the Nafion membrane. Thus, a clear image of electroconvective vortices near the Nafion membrane could be obtained and visualized. As a result, we observed that the heterogeneous membrane has relatively stronger electroconvective vortices compared to the Nafion homogeneous membranes. Regarding electrical response, the Nafion membrane has a higher limiting current and less overlimiting current compared to the heterogeneous membrane. Based on our visualization, it is assumed that the heterogeneous membrane has more activated electroconvective vortices, which lower electrical resistance in the overlimiting current regime. We anticipate that this work can contribute to the fundamental understanding of the ion transport characteristics depending on the homogeneity of ion exchange membranes.

Abstract
1. 서 론
2. 이론 및 실험방법
    2.1. 이론적 배경
    2.2. 실험장치 제작
    2.3. 실험 방법
3. 결과 및 고찰
    3.1. 표면 형상 관찰
    3.2. 유동 가시화
    3.3. 전류-전압 특성 곡선
4. 결 론
Acknowledgement
References

• 조명현(공주대학교 미래융합공학과) | Myeonghyeon Cho (Department of Future Convergence Engineering, Kongju National University, Cheonan 31080, Republic of Korea)
• 최진웅(공주대학교 미래융합공학과) | Jinwoong Choi (Department of Future Convergence Engineering, Kongju National University, Cheonan 31080, Republic of Korea)
• 김범주(공주대학교 미래융합공학과, 공주대학교 기계자동차공학부) | Bumjoo Kim (Department of Future Convergence Engineering, Kongju National University, Department of Mechanical & Automotive Engineering, Kongju National University) Corresponding author