About

Thomas Cubaud is an Associate Professor in the Department of Mechanical Engineering at Stony Brook University. He holds a Ph.D. from Paris-Sud University/ESPCI obtained in 2001. His research focuses on microfluidics, multiphase flows, interfacial fluid dynamics, nanotechnologies, and related areas. His work involves exploring the behavior of fluids at small scales, interfacial phenomena, and the development of nanotechnologies, contributing to advancements in these fields through experimental and theoretical approaches.

Research topics

• Materials science
• Nanotechnology
• Optics
• Physics
• Classical mechanics
• Optoelectronics
• Mechanics
• Composite material

Selected publications

• Droplet microfluidic method for measurement of ultralow interfacial tension in ternary fluid systems

  Lab on a Chip · 2025-01-01 · 1 citations

  articleSenior authorCorresponding

  , when solvent diffusion into the continuous phase has a negligible effect on flow morphologies. We examine a wide range of flow rates and delineate vast flow maps of droplet regimes, including dripping and jetting flows, to clarify the hydrodynamic behavior of conjugate fluid mixtures in square microcapillaries. A method based on analysis of droplet size and spacing is implemented to predict the role of the miscible fluid additive concentration in microfluidic multiphase flows of water-isopropanol and ethanol-isopropanol blends in viscous silicone oil. This approach enables measurement of extremely small values of interfacial tension at large solvent concentrations. This work shows a technique for exploring and characterizing numerous ternary flow systems of interest with a variety of organic solvents and oils.

  PublisherDOI

• Dynamic wetting transitions of droplets in coaxial liquid-liquid microflows

  SSRN Electronic Journal · 2025-01-01

  preprintOpen access1st authorCorresponding
  PublisherDOI

• Formation of microfluidic droplets and jets in a solvent-rich oil phase

  Flow · 2025-01-01

  articleOpen accessSenior authorCorresponding

  Abstract We develop original flow-based methods to interrogate and manipulate out-of-equilibrium behaviour of ternary fluids systems at the small scale. In particular, we examine droplet and jet formation of ternary fluid systems in coaxial microchannels when an aqueous phase is injected into a solvent-rich oil phase using common fluids, such as ethanol for the aqueous phase, silicone oil for the oil phase and isopropanol for the solvent. Alcohols are often employed to impart oil and water properties with a myriad of practical uses as extractants, antiseptics, wetting agents, emulsifiers or biofuels. Here, we systematically examine the role of alcohol solvents on the hydrodynamic stability of aqueous–oil multiphase flows in square microchannels. Broad variations of flow rates and solvent concentration reveal a variety of intriguing droplet and jet flow regimes in the presence of spontaneous emulsification phenomena and significant mass transfer across the fluid interface. Typical flow patterns include dripping and jetting droplets, phase inversion and dynamic wetting and conjugate jets. Functional relationships are developed to model the evolution of multiphase flow characteristics with solvent concentration. This work provides insights into complex natural phenomena relevant to the application of microfluidic droplet systems to chemical assays as well as fluid measurement and characterisation technologies.

  PublisherOA PDFDOI

• Poster: Permeable Droplets and Jets in Microchannels

  2024-11-21

  articleOpen access1st authorCorresponding
  PublisherDOI

• Microfluidic dissolution of nanoemulsions in solvents

  Soft Matter · 2024-01-01 · 1 citations

  articleSenior authorCorresponding

  We experimentally investigate the behavior of nanoemulsion and microscale emulsion jets flowing in solvents using coaxial microfluidic devices. The stability of colloidal dispersions made of oil droplets dispersed in water is significantly altered by the presence of a miscible solvent, which induces complex solutal and droplet coalescence instabilities over various timescales. We reveal intriguing microflow patterns of oil-in-water micro- and nanoemulsion threads in a continuous phase of isopropanol, including the dissolving, diffusive, gravitational, and stable thread regimes. We discuss the evolution of core-annular flow characteristics and develop scaling relationships to model thread dynamics through measurements of effective diameter as well as persistence and gravitational lengths. A microflow method based on dynamic similitude is developed to estimate the diffusion coefficients of nanoemulsions and microscale emulsions in miscible solvents. This work shows the possibility to process soft colloidal dispersions and control degradation mechanisms using microfluidic techniques.

  PublisherDOI

• Microflow of nanoemulsion threads in surfactant solutions

  Physical review. E · 2023-01-06 · 3 citations

  articleSenior author

  We experimentally investigate the microfluidic flow of oil-in-water nanoemulsions in aqueous sodium dodecyl sulfate (SDS) solutions having different concentrations and injection flow rates. A coaxial microfluidic device is employed to explore the behavior of nanoemulsion threads in these sheathing SDS solutions. Using two high-speed cameras, which simultaneously capture both top and side views, we reveal a variety of flow phenomena, ranging from simple core-annular flow to complex flows, such as gravitational, inertial, and buckling thread flows. By analyzing these complex flows, we develop a methodology that elucidates the relationship of core-annular and gravitational flows at low flow rates. Further, we examine the off-axis displacements and bending of core threads at large flow rates, and we study the buckling dynamics of nanoemulsion threads subjected to osmotic stresses caused by large SDS concentrations in the sheathing fluid.

  PublisherDOI

• Microfluidic elongation of viscous droplets at vanishing interfacial tension

  Physical Review Fluids · 2023-10-25 · 3 citations

  article1st authorCorresponding

  The dynamic response of viscous droplets to a sudden change of interfacial tension with the external phase is systematically examined in microchannels. A two-step hydrodynamic focusing section is employed to continuously generate high-viscosity oil droplets in immiscible alcohols at the first junction and inject droplets into miscible alcohol phases at the second junction. Upon entering stratifications, droplets are seen to strongly elongate depending on fluid properties and flow conditions. Functional relationships are developed to characterize droplet dynamics in a variety of solvents and examine out-of-equilibrium behavior of ternary systems at short-time scales.

  PublisherDOI

• Glass surface micromachining with simultaneous nanomaterial deposition by picosecond laser for wettability control

  Applied Surface Science · 2021 · 24 citations

  • Materials science
  • Nanotechnology
  • Optics
  PublisherOA PDFDOI

• Role of Interfacial Tension on Viscous Multiphase Flows in Coaxial Microfluidic Channels

  Langmuir · 2021-06-11 · 17 citations

  articleSenior authorCorresponding

  We experimentally investigate the influence of interfacial tension on liquid/liquid microflows for fluids having large viscosity contrasts. A coaxial microdevice is employed to examine the situation where a less-viscous fluid is injected in a sheath of a more-viscous fluid using both immiscible and miscible fluid pairs. Data obtained from high-speed imaging reveal a variety of regular flow regimes, including dripping, jetting, wavy, core-annular, diffusive jet, mist, and inverted thread flow patterns. Flow maps are delineated over a wide range of injection flow rates, and an original methodology based on periodic pattern analysis is developed to clarify relationships between interfacial dynamics and fluid properties of multiphase materials. Specifically, we show the smooth evolution of droplet size and spacing at the transition between dripping and jetting flows and develop scaling relationships based on capillary numbers to predict droplet flow morphologies. For similar flow conditions, reducing interfacial tension leads to a significant decrease in droplet size. For miscible fluid pairs, diffusive jets are observed at low Péclet numbers, whereas wavy core-annular flows are obtained at moderate Reynolds numbers for both immiscible and miscible fluids. This work provides a unifying description of the influence of interfacial properties on viscous microflow phenomena.

  PublisherDOI

• Diffusive and capillary instabilities of viscous fluid threads in microchannels

  Physical Review Fluids · 2021-09-07 · 12 citations

  article1st authorCorresponding

  We experimentally investigate the flow behavior of viscous oil threads in a a variety of miscible and immiscible low-molecular weight alcohols in microchannels. A comparative study is conducted between diffusive and capillary regimes using simple functional relationships for the thread characteristics, including diameter and detachment length. We develop a comprehensive classification of immiscible and miscible fluid dynamics in square microfluidic channels and provide a quantitative analysis of the evolution of multiphase flow properties across flow patterns.

  PublisherDOI

Recent grants

• CAREER: Microflow of highly viscous fluids: mixing and dissolution processes

  NSF · $442k · 2012–2018

• Dynamics of capillary threads and high-viscosity droplets in microfluidic systems

  NSF · $241k · 2009–2012

• Dynamics of Spontaneous Emulsification in Microchannels

  NSF · $360k · 2022–2026

Frequent coauthors

• Thomas G. Mason

  22 shared

• Xiaoyi Hu

  Zhejiang A & F University

  19 shared

• Bibin Jose

  16 shared

• Carlos E. Colosqui

  Stony Brook University

  14 shared

• David J. Hwang

  State University of New York

  11 shared

• Samira Darvishi

  Tabriz University of Medical Sciences

  11 shared

• Chih‐Ming Ho

  Samueli Institute

  10 shared

• Dhiraj Nandyala

  Stony Brook University

  10 shared

Education

• Ph.D., Mechanical Engineering

  University of California, Berkeley

  2004

• M.S., Mechanical Engineering

  University of California, Berkeley

  2000

• B.S., Mechanical Engineering

  University of California, Berkeley

  1999