DropletPub Date : 2026-07-28Epub Date: 2026-03-25DOI: 10.1002/dro2.70065
Isaac Berk, Emilie Luong, H. Jeremy Cho
{"title":"Beyond goniometry: 3D digital twinning of droplets from a single image","authors":"Isaac Berk, Emilie Luong, H. Jeremy Cho","doi":"10.1002/dro2.70065","DOIUrl":"https://doi.org/10.1002/dro2.70065","url":null,"abstract":"<p>Wettability characterizations are crucial to many disciplines, including dropwise condensation heat transfer, microfluidics, and self-cleaning materials. Droplet goniometry is a standard technique for such characterizations due to its relatively simple setup and execution. However, goniometry is severely limited when analyzing irregular droplets and multi-droplet systems, and alternative methods often require additional equipment, exhaustive scans, or non-physics-based modeling, hindering their effectiveness. In response, we created the reverse catch light method, which constructs physics-informed, three-dimensional digital twins of droplets from a single overhead image. We locate droplet contact lines and point light reflections on a real droplet surface, then iteratively solve the Young‒Laplace equation to generate candidate droplet surfaces whose unique reflections match those observed in our image. We experimentally validated this method with goniometry across varied droplet contact angles, volumes, liquid types, and substrates. Furthermore, we highlight new capabilities that are impractical with classical goniometry, such as constructing digital twins of irregularly shaped droplets or sliding droplets for hysteresis characterization. Finally, we demonstrate the ability to obtain rich, spatiotemporal statistical data from multi-droplet systems that would be impossible with classical goniometry. Our findings suggest that this methodology could be easily deployed for enhanced in situ diagnostics of otherwise difficult-to-analyze, realistic systems.</p>","PeriodicalId":100381,"journal":{"name":"Droplet","volume":"5 3","pages":""},"PeriodicalIF":9.1,"publicationDate":"2026-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dro2.70065","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148615848","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
DropletPub Date : 2026-07-28DOI: 10.1002/dro2.70096
Jinzhao Liu, Tianyou Wang, Zhizhao Che
{"title":"Inside Back Cover, Volume 5, Number 3, July 2026","authors":"Jinzhao Liu, Tianyou Wang, Zhizhao Che","doi":"10.1002/dro2.70096","DOIUrl":"https://doi.org/10.1002/dro2.70096","url":null,"abstract":"<p><b>Inside Back Cover</b>: The cover image is based on the Research Article <i>Dynamics of cavitation bubbles in a liquid layer</i> by Liu et al.</p><p><b>Cover description</b>: Cover description: The cover visualizes the evolution of a cavitation bubble confined within a liquid layer, from growth and collapse to jetting, toroidal breakup, and free-surface splashing. This study reveals how the competing effects of a rigid wall and a free surface govern bubble migration, collapse morphology, and interfacial motion through confinement-dependent Kelvin impulse. (DOI: 10.1002/dro2.70079)\u0000\u0000 <figure>\u0000 <div><picture>\u0000 <source></source></picture><p></p>\u0000 </div>\u0000 </figure></p>","PeriodicalId":100381,"journal":{"name":"Droplet","volume":"5 3","pages":""},"PeriodicalIF":9.1,"publicationDate":"2026-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dro2.70096","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148616300","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
DropletPub Date : 2026-07-28Epub Date: 2026-06-12DOI: 10.1002/dro2.70079
Jinzhao Liu, Tianyou Wang, Zhizhao Che
{"title":"Dynamics of cavitation bubbles in a liquid layer","authors":"Jinzhao Liu, Tianyou Wang, Zhizhao Che","doi":"10.1002/dro2.70079","DOIUrl":"https://doi.org/10.1002/dro2.70079","url":null,"abstract":"<p>Cavitation phenomena are widespread in nature and industrial applications. Researchers have conducted in-depth studies on the interaction of cavitation bubbles with a single boundary. However, when cavitation bubbles interact simultaneously with multiple boundaries, for example, a rigid wall and free surface, the process and mechanisms are still unclear. Here, experiments are carried out to study the dynamics of cavitation bubbles within a liquid layer. The results show that due to the combined effect of a rigid wall and free surface, the bubbles exhibit a significant downward migration in the liquid layer. Based on Kelvin impulse theory, we calculate the impulse experienced by the bubble and find a good consistency between the downward migration of the bubble and the impulse it experiences. By varying the initial position of the bubble in the liquid layer, we find that the confinement effect of the rigid wall significantly affects the bubble's collapse morphology, leading to different post-collapse phenomena of free surface motion.</p>","PeriodicalId":100381,"journal":{"name":"Droplet","volume":"5 3","pages":""},"PeriodicalIF":9.1,"publicationDate":"2026-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dro2.70079","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148615235","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
DropletPub Date : 2026-07-28Epub Date: 2026-04-08DOI: 10.1002/dro2.70067
Tyler R. McCoy, Mohammad Alipanahrostami, Chase Wright, Saman Faraji Gargari, Mi Li, Shinyun Park, Tiezheng Tong, Wei Wang
{"title":"3D printing of fluorine-free omniphobic surfaces","authors":"Tyler R. McCoy, Mohammad Alipanahrostami, Chase Wright, Saman Faraji Gargari, Mi Li, Shinyun Park, Tiezheng Tong, Wei Wang","doi":"10.1002/dro2.70067","DOIUrl":"https://doi.org/10.1002/dro2.70067","url":null,"abstract":"<p>Omniphobic surfaces have attracted considerable interest in recent years due to their various applications. Such surfaces conventionally require a fluorine-based surface chemistry with a low surface energy, which is achieved through surface modification using per- and polyfluoroalkyl substances (PFAS). However, PFAS, as emerging contaminants, pose serious health risks to humans and wildlife. The discovery of doubly reentrant texture has paved the way for designing fluorine-free omniphobic surfaces, but current methods for fabricating this unique texture involve complex processes and expensive equipment. In this work, we demonstrate that the simple and inexpensive digital light processing three-dimensional printing can be used to fabricate not only doubly reentrant but also triply reentrant micropillars. Our printed micropillars with doubly reentrant features display repellency towards liquids with a wide range of surface tensions after surface modification using a hydrocarbon silane. Water and ethanol droplets remain in the Cassie–Baxter state during the entire evaporation process, indicating the robust omniphobicity of our surface. Moreover, the printed micropillars with triply reentrant features exhibit omniphobicity even when the micropillars are composed of hydrophilic resin. Our simple method for achieving fluorine-free omniphobicity has the potential of facilitating the development of sustainable liquid-repellent surfaces and the mitigation of PFAS contamination.</p>","PeriodicalId":100381,"journal":{"name":"Droplet","volume":"5 3","pages":""},"PeriodicalIF":9.1,"publicationDate":"2026-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dro2.70067","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148615399","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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