【公開日：2025.06.10】【最終更新日：2025.05.29】
課題データ / Project Data
課題番号 / Project Issue Number
24UT1171
利用課題名 / Title
Elucidation of drying patterns of polymer droplets
利用した実施機関 / Support Institute
東京大学 / Tokyo Univ.
機関外・機関内の利用 / External or Internal Use
内部利用（ARIM事業参画者以外）/Internal Use (by non ARIM members)
技術領域 / Technology Area
【横断技術領域 / Cross-Technology Area】（主 / Main）計測・分析/Advanced Characterization（副 / Sub）-
【重要技術領域 / Important Technology Area】（主 / Main）その他/Others（副 / Sub）-
キーワード / Keywords
形状・膜厚・電気特性評価装置群, 共焦点顕微鏡、高分子材料,光学顕微鏡/ Optical microscope
利用者と利用形態 / User and Support Type
利用者名（課題申請者）/ User Name (Project Applicant)
Yanagisawa Miho
所属名 / Affiliation
東京大学東京大学大学院総合文化研究科広域科学専攻
共同利用者氏名 / Names of Collaborators in Other Institutes Than Hub and Spoke Institutes
Pal Anusura
ARIM実施機関支援担当者 / Names of Collaborators in The Hub and Spoke Institutes
利用形態 / Support Type
（主 / Main）機器利用/Equipment Utilization（副 / Sub）,機器利用/Equipment Utilization
利用した主な設備 / Equipment Used in This Project
報告書データ / Report
概要（目的・用途・実施内容）/ Abstract (Aim, Use Applications and Contents)
Our goal is to quantify the thickness of dried polymer films by obtaining height profile images for different film samples. These height profiles allow us to:Assess Film Uniformity – Whether the thickness is consistent across the surface.Compare Different Polymer Films – Evaluate how different polymer compositions, drying conditions, or deposition techniques affect the final thickness.
実験 / Experimental
Samples of healthy serum and those with abnormalities are used. There are three types of samples-- healthy, low diabetes, and high diabetes
A 2 mm diameter drop of the serum solution is deposited on a clean glass substrate. The drop is allowed to dry overnight to ensure complete solvent evaporation .Once dried, the film is placed under a height profilometer. The profilometer scans the surface to create a 3D height profile, capturing variations in thickness across the dried polymer region. as shown in Figure 1 and 2.
結果と考察 / Results and Discussion
The 3D height profilometry scans of two dried polymer films reveal distinct surface morphologies, with notable differences in the distribution of height across the film. The corresponding height profile provides a cross-sectional view of height variations along a normalized distance.Observations from 3D Height Mapshealthy serum dried films: This dried polymer film exhibits a pronounced coffee-ring effect, with significant height accumulation at the periphery (～58.9 µm) and a central region that appears much thinner. The rough, uneven surface suggests possible cracking, phase separation, or non-uniform solvent evaporation during drying. The presence of multiple peaks and valleys indicates material redistribution, likely due to capillary flows or Marangoni convection. Serum-dried films with abnormalities: The film shows a more uniformly spread deposition with a central bulge, where the highest thickness is ～48.7 µm. Unlike the first case, this film does not exhibit significant cracking or edge accumulation, suggesting a more controlled drying process. The film’s height profile suggests gradual thinning towards the edges, characteristic of sessile drop evaporation with pinned contact lines.3. Cross-sectional Height Profile Analysis: Two prominent peaks (～50 µm) at the edges indicate height accumulation, with a central region of lower thickness (～10 µm) for healthy, whereas, for the serum with abnormalities, ～50 µm at the edges indicate height accumulation, with a central region of lower thickness (～20 µm). The presence of minor oscillations in the height curve could be due to surface roughness or polymer aggregation during solvent evaporation.
Discussion: Drying Mechanism and Film Morphology: Evaporation-driven flows within the polymer droplet strongly influence the observed height variations and ring-like structures. The film with cracked peripheral structures suggests higher polymer concentration, rapid evaporation, or phase separation, leading to stress accumulation and eventual rupture. The second, more uniform film likely results from slower drying rates or higher molecular weight polymers, which more effectively resist capillary-driven motion. The height profile confirms edge-thickening, which is characteristic of coffee-ring effects in drying polymer solutions. Therefore, the height profilometry analysis successfully characterizes the thickness distribution of dried polymer films, which helps us to understand the mechanical stress distribution during the drying process. Differences in film morphology arise due to drying dynamics, affecting uniformity, roughness, and structural integrity. Optimizing deposition and drying conditions could improve film homogeneity for various applications in biomedical diagnostics and material coatings.
図・表・数式 / Figures, Tables and Equations
Figure 1: Height Profilometry Analysis of a "Healthy" Polymer Film.
Figure 2: Height Profilometry Analysis of a "diseased" Polymer Film.
その他・特記事項（参考文献・謝辞等） / Remarks(References and Acknowledgements)
We want to thank Mitsuhiro Yoda for his valuable time and support. Without him, we could not have done these experiments and gained the insights that have a bigger impact on our research.
成果発表・成果利用 / Publication and Patents
論文・プロシーディング（DOIのあるもの） / DOI (Publication and Proceedings)
口頭発表、ポスター発表および、その他の論文 / Oral Presentations etc.
特許 / Patents
特許出願件数 / Number of Patent Applications：0件
特許登録件数 / Number of Registered Patents：0件