Droplet最新文献

{"title":"Dynamic manipulation of multiphase fluid in microgravity using photoresponsive surfactant","authors":"Xichen Liang,&nbsp;Kseniia M. Karnaukh,&nbsp;Qixuan Cao,&nbsp;Marielle Cooper,&nbsp;Hao Xu,&nbsp;Ian Maskiewicz,&nbsp;Olivia Wander,&nbsp;Javier Read de Alaniz,&nbsp;Yangying Zhu,&nbsp;Paolo Luzzatto-Fegiz","doi":"10.1002/dro2.70081","DOIUrl":"https://doi.org/10.1002/dro2.70081","url":null,"abstract":"<p>Control of bubble motion is essential for improving efficiency and creating new functionalities in electrochemistry, heat transfer, and biomedical systems. Photoresponsive surfactants enable bubble manipulation by creating surface-tension gradients, inducing a “photo-Marangoni” flow under illumination, without the need for engineered substrates, by leveraging a reversible switch in molecular conformation. Although previous studies have demonstrated bubble manipulation using photo-responsive surfactants, a comprehensive understanding of how fluid behavior is affected by critical parameters, such as bubble size, illumination, photo-switching kinetics, concentration, and adsorption/desorption kinetics, remains elusive. Advances have been limited by the complex multiphysics processes involved, and by the fact that earth-bound experiments couple bubble photo-Marangoni dynamics with interference from buoyancy and photo-thermal convection. We elucidate the factors enabling fast photo-Marangoni-driven bubble motion, by performing microgravity experiments, enabled by a bespoke photo-surfactant, complemented by a detailed modeling framework. We identify an optimal bubble size for migration (radius <span></span><math>\u0000 <semantics>\u0000 <mo>∼</mo>\u0000 <annotation>$sim$</annotation>\u0000 </semantics></math>1 mm), since smaller and larger bubbles incur weaker photo-Marangoni stresses and larger drag, respectively. Surfactants that switch rapidly under illumination drive fast migration, provided their reverse switch (in darkness) is 10–<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mn>100</mn>\u0000 <mo>×</mo>\u0000 </mrow>\u0000 <annotation>$100times$</annotation>\u0000 </semantics></math> slower. These foundational results enable the synthesis of next-generation photo-surfactants and photo-Marangoni manipulation across multiphase fluid 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/dro2.70081","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148616305","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}

{"title":"Hand-powered and programmable electrowetting-on-dielectric droplet actuation enabled by triboelectric nanogenerator and mechanically encoded punch-card switch array","authors":"Jing Ding,&nbsp;Kuan-Lun Ho,&nbsp;Jesus Becerra,&nbsp;Paul Kessinger,&nbsp;Wen-Quan Tao,&nbsp;Shih-Kang Fan","doi":"10.1002/dro2.70082","DOIUrl":"https://doi.org/10.1002/dro2.70082","url":null,"abstract":"<p>Electrowetting-on-dielectric (EWOD) enables electrical modulation of liquid contact angle and is widely used for droplet actuation; however, its reliance on bulky high-voltage power supplies limits portability. Triboelectric nanogenerators (TENGs) provide a lightweight, mechanically driven alternative, yet existing EWOD–TENG systems still rely on electronic controllers or rapid manual actions. Here, we present a hand-powered and mechanically programmable EWOD platform that integrates a contact-separation TENG (CS-TENG) with a mechanically encoded punch-card switch array, both driven by a single hand-crank mechanism. Hand cranking simultaneously generates high voltage for EWOD actuation and advances a punch-card tape to sequentially trigger electrode switching according to predefined punch-hole patterns. Unlike conventional voltage sources, the CS-TENG delivers a constant-charge output per cycle, leading to distinct EWOD behavior. An EWOD–TENG model with trapped charge elucidates key phenomena, including bias-dependent asymmetric EWOD arising from dielectric charge trapping and stepwise voltage attenuation caused by capacitive EWOD loading during sequential switching. The punch-card switch array converts physical hole patterns into time-synchronized electrode activation, enabling programmable droplet manipulation without electronic controllers. The resulting platform executes predefined droplet operations using only a hand crank as the sole energy and control input, achieving autonomous, portable, and robust droplet control for field-deployable microfluidic 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/dro2.70082","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148615250","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}

{"title":"Inside Front Cover, Volume 5, Number 3, July 2026","authors":"Sanghyeon Chang,&nbsp;Srikar Arani,&nbsp;Nishant Sai Nuthalapati,&nbsp;Youngjoon Suh,&nbsp;Nicholas Choi,&nbsp;Siavash Khodakarami,&nbsp;Md Rakibul Hasan Roni,&nbsp;Nenad Miljkovic,&nbsp;Aparna Chandramowlishwaran,&nbsp;Yoonjin Won","doi":"10.1002/dro2.70095","DOIUrl":"https://doi.org/10.1002/dro2.70095","url":null,"abstract":"<p><b>Inside Front Cover</b>: The cover image is based on the Research Article <i>EventFlow: Real-time neuromorphic event-driven classification of two-phase boiling flow regimes</i> by Chang et al.</p><p><b>Cover description</b>: The cover illustrates a neuromorphic event sensor capturing the rapid evolution of bubbles and vapor structures in a flow boiling channel. By converting interfacial motion into sparse asynchronous events, the EventFlow framework enables fast, real-time classification of boiling regimes. The artwork highlights the transition from discrete bubbles to slug and wavy vapor patterns across operating conditions. (DOI: 10.1002/dro2.70066)\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/dro2.70095","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148616295","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}

{"title":"Front Cover, Volume 5, Number 3, July 2026","authors":"Jing Ding,&nbsp;Kuan-Lun Ho,&nbsp;Jesus Becerra,&nbsp;Paul Kessinger,&nbsp;Wen-Quan Tao,&nbsp;Shih-Kang Fan","doi":"10.1002/dro2.70093","DOIUrl":"https://doi.org/10.1002/dro2.70093","url":null,"abstract":"<p><b>Front Cover</b>: The cover image is based on the Research Article <i>Hand-powered and programmable electrowetting-on-dielectric droplet actuation enabled by triboelectric nanogenerator and mechanically encoded punch-card switch array</i> by Ding et al.</p><p><b>Cover description</b>: A hand-powered, programmable droplet actuation platform integrates a triboelectric nanogenerator (TENG), a punch-card switch array repurposed from a music box, and an electrowetting chip. Hand cranking drives the TENG to generate the voltage for electrowetting, while advancing a punch-card tape that sequentially activates switches, allowing the droplets to “dance” in harmony with the “music” encoded on the punch card. (DOI: 10.1002/dro2.70082)\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/dro2.70093","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148616297","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}

{"title":"Silicone oil–based ferrofluid microrobots for versatile magnetic digital microfluidics","authors":"Pu Liu,&nbsp;Leilei Chen,&nbsp;Yulei Fu,&nbsp;Wendong Wang","doi":"10.1002/dro2.70074","DOIUrl":"10.1002/dro2.70074","url":null,"abstract":"<p>Magnetic digital microfluidics offers a promising alternative to the dominant electrowetting-based digital microfluidics but faces significant challenges regarding system portability, sample contamination, and limited functionality. Here, we report a magneto-silicobotic system utilizing silicone oil–based ferrofluid droplets as inert microrobots for versatile manipulation of droplets and solid particles. The system combines a cost-effective and portable microcoil array with a millimeter-scale permanent magnet to generate localized magnetic fields for precise actuation. It achieves precise droplet manipulation with an average tracking error of 0.15 mm, stable operation over 360 cycles, and speeds up to 52 mm/s. It can transport droplets 50 times its volume, achieve maximum transport speeds of 35 mm/s, maintain long-term residual-free transport, and handle diverse liquids, including organic solvents and biological samples. We further design a ferrofluid-based pipette to perform droplet splitting and dispensing, thus completing all basic operations of digital microfluidics. Additionally, we extend the robot's capability to include the transport and automated assembly of solid particles using integrated visual feedback. We envision that this portable, additive-free platform will have a significant impact on point-of-care testing, miniaturized biochemical assays, and automated lab-on-a-chip 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/dro2.70074","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148305596","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}

{"title":"Manipulating drying-induced carbon nanotube assemblies through substrate surface engineering","authors":"Ke Shui,&nbsp;Deng Pan,&nbsp;Tongtong Qin,&nbsp;Wenxin Xiao,&nbsp;Xin Li,&nbsp;Hao Yang,&nbsp;Jian Lin,&nbsp;Qingguang Xie,&nbsp;Jens Harting,&nbsp;Song Qiu,&nbsp;Chang-Qi Ma","doi":"10.1002/dro2.70072","DOIUrl":"https://doi.org/10.1002/dro2.70072","url":null,"abstract":"<p>The unique one-dimensional structure and outstanding optoelectronic properties of carbon nanotubes (CNTs) have motivated extensive research into their directed assembly. Although the droplet evaporation method offers a straightforward strategy for aligning CNTs, controlling the final deposited structure remains challenging due to the inherently high aspect ratio of CNTs. In this study, we prepared four substrates with distinct wettability and friction properties through surface modification. Time-resolved contact angle analysis was employed to monitor the evolution of the three-phase contact line and the evaporation kinetics of CNT droplets on these substrates. Combined with detailed microstructural characterization, we found that on hydrophobic, highly friction surfaces (NBE-modified silica), strong friction stabilizes the contact line during droplet drying. At the same time, rapid solvent evaporation induces droplet shrinkage, leading to a pronounced circumferential flow along the droplet periphery. This flow promotes the formation of long-range aligned CNT orientation bands with a width of ∼150 <span></span><math>\u0000 <semantics>\u0000 <mi>μ</mi>\u0000 <annotation>$umu$</annotation>\u0000 </semantics></math>m (orientation degree of 9.2°) after drying. These findings provide insights for the design and modification of substrates used in evaporation-driven oriented assembly of CNTs.</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/dro2.70072","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148615261","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}

{"title":"Back Cover, Volume 5, Number 3, July 2026","authors":"Pu Liu,&nbsp;Leilei Chen,&nbsp;Yulei Fu,&nbsp;Wendong Wang","doi":"10.1002/dro2.70094","DOIUrl":"https://doi.org/10.1002/dro2.70094","url":null,"abstract":"<p><b>Back Cover</b>: The cover image is based on the Research Article <i>Silicone oil-based ferrofluid microrobots for versatile magnetic digital microfluidics</i> by Liu et al.</p><p><b>Cover description</b>: This cover illustrates a silicone oil-based ferrofluid microrobot manipulating a nonmagnetic aqueous droplet through a wrapping layer and wetting ridge on a slippery liquid-infused porous surface. The microrobot can transport droplets up to 50 times its own volume, while a portable printed circuit board (PCB) microcoil array drives a millimeter-scale permanent magnet for localized magnetic actuation. (DOI: 10.1002/dro2.70074)\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/dro2.70094","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148616294","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}

{"title":"Enhancing hydrogen evolution reaction by harnessing bubble dynamics regulation: Principles, methods, and outlook","authors":"Ziwei Guo,&nbsp;Chunhui Zhang,&nbsp;Yunxun Liu,&nbsp;Yi Han,&nbsp;Jinghang Pan,&nbsp;Lingyao Zhang,&nbsp;Chuanqi Nie,&nbsp;Yuejing Zhao,&nbsp;Kesong Liu,&nbsp;Cunming Yu,&nbsp;Lei Jiang","doi":"10.1002/dro2.70073","DOIUrl":"https://doi.org/10.1002/dro2.70073","url":null,"abstract":"<p>Electrocatalytic hydrogen evolution reaction (HER) is crucial for green hydrogen production and the transition toward low-carbon energy systems. However, the issues related to electrochemical gas bubbles, particularly at high current densities, have become a critical bottleneck for HER performance, resulting in active site isolation, increased ohmic resistance, and large concentration overpotential. Addressing these bubble-related limitations is therefore essential for advancing HER efficiency. This review aims to provide a comprehensive understanding of bubble manipulation strategies for enhancing HER by (1) exploring the fundamental principles governing bubble dynamics at electrode interfaces, (2) presenting the strategies to mitigate bubble-related issues at electrode interfaces, that is, passive strategies and active strategies, and (3) offering our insights into the challenges and opportunities for bubble dynamics in HER. By consolidating these projects, this review aims to advance the rational design of bubble management strategies and inspire innovative approaches for efficient hydrogen production.</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/dro2.70073","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148615234","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}

{"title":"Droplet microfluidics: Enabling the tailored fabrication of hydrogel particles","authors":"Zhongqiao Gan,&nbsp;Xu Hou","doi":"10.1002/dro2.70068","DOIUrl":"https://doi.org/10.1002/dro2.70068","url":null,"abstract":"<p>Hydrogel particles are attracting increasing interest as tunable microscale platforms that combine precise architectures with diverse chemical, biological, and physical functionalities. Among fabrication strategies, droplet microfluidics has emerged as a powerful technology for producing monodisperse hydrogel particles with controllable size, composition, and internal structure via precise regulation of microscale fluid dynamics. This review first outlines the fundamental principles of droplet microfluidics, including chip fabrication, channel design, droplet generation dynamics, energy input modes, and fluidic compositions, which collectively underpin reliable particle production. We then highlight compatible hydrogel precursor systems, gelation methods, and functionalization strategies for engineering tailored hydrogel particles. The versatility of such particles is further emphasized, supporting applications in cell culture, 3D bioprinting, drug delivery, and diagnostics. Finally, we provide an outlook on future directions, including system parallelization, process automation, and artificial intelligence integration, anticipated to expand the scalability, functionality, and multidisciplinary impact of droplet-microfluidic hydrogel platforms.</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/dro2.70068","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148615257","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}

{"title":"EventFlow: Real-time neuromorphic event-driven classification of two-phase boiling flow regimes","authors":"Sanghyeon Chang,&nbsp;Srikar Arani,&nbsp;Nishant Sai Nuthalapati,&nbsp;Youngjoon Suh,&nbsp;Nicholas Choi,&nbsp;Siavash Khodakarami,&nbsp;Md Rakibul Hasan Roni,&nbsp;Nenad Miljkovic,&nbsp;Aparna Chandramowlishwaran,&nbsp;Yoonjin Won","doi":"10.1002/dro2.70066","DOIUrl":"https://doi.org/10.1002/dro2.70066","url":null,"abstract":"<p>Flow boiling is an efficient heat transfer mechanism capable of dissipating high heat loads with minimal temperature variation, making it an ideal thermal management method. However, sudden shifts between flow regimes can disrupt thermal performance and system reliability, highlighting the need for accurate and low-latency real-time monitoring. Conventional optical imaging methods are limited by high computational demands and insufficient temporal resolution, making them inadequate for capturing transient flow behavior. To address this, we propose a real-time framework based on signals from neuromorphic sensors for flow regime classification. Neuromorphic sensors detect changes in brightness at individual pixels, which typically correspond to motion at edges, enabling fast and efficient detection without full-frame reconstruction and providing event-based information. We develop five classification models using both traditional image data and event-based data, demonstrating that models leveraging event data outperform frame-based approaches due to their sensitivity to dynamic flow features. Among these models, the event-based long short-term memory model provides the best balance between accuracy and speed, achieving 97.6% classification accuracy with a processing time of 0.28 ms. Our asynchronous processing pipeline supports continuous, low-latency predictions and delivers stable output through a majority voting mechanisms, enabling reliable real-time feedback for experimental control and intelligent thermal management.</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/dro2.70066","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148615278","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}