Mid-April stood the Annual European Rheology Conference (AERC) in Lyon, France, and we were proud to attend and represent microfluidics in the wide world of rheology.
Hosted at the Lyon Conference Center, the event lasted for three days and gathered experts from across the globe. After a warm welcome from Prof. Khalid Lamnawar, Chair of AERC 2025, the conference officially opened with an extensive program featuring 581 contributions, nine parallel sessions, and a record-breaking of 140 poster presentations!
Rheology is a vast and dynamic field, and as expected, new trends are emerging across a variety of applications. These include the miniaturization of experiments through microrheology powered by microfluidics, the integration of AI and machine learning for predictive modeling, high-throughput techniques for greater accuracy and efficiency, and promising intersections with biology to study the rheological behavior of biological materials.
For those less familiar with the field, you might be wondering — what exactly is rheology?Rheology is the study of the flow and deformation of matter. It explores how materials respond to force, deformation, and time. Derived from the Greek words rheo (to flow) and logia (study), rheology is not only about how liquids flow, it also examines how solid-like materials deform. In particular, it focuses on non-Newtonian fluids like viscoplastic for example, which exhibit both solid and liquid behavior depending on the applied stress or strain over time.
If you want to learn more about it, we’ve created a handy toolbox to help you better understand the key terms and concepts discussed:
Tuesday morning’s opening talk was launched with an insightful talk by Prof. Philippe Coussot titled “Fifty Shades of Yield Stress Fluids: Rheological Challenges and Engineering Perspectives.”
Representing the Laboratoire Navier at Université Gustave Eiffel in Champs-sur-Marne, he introduced the growing study of yield stress fluids—materials like toothpaste, cement, mortar, foam, mud, and even mayonnaise. Once debated, these complex materials are now fully recognized by physicists as a distinct state of matter, studied for their unique mechanical behavior. Yield stress fluids are attracting growing interest thanks to their expanding use in real-world applications, from additive manufacturing and 3D printing in bioengineering to civil engineering and food processing.
In the afternoon, we attended a presentation titled “Viscoelastic Properties of Associating Polymers: When Several Dynamics Are Coming into Play” by Evelyne van Ruymbeke, from the Bio and Soft Matter group at the Institute of Condensed Matter and Nanosciences in Louvain-la-Neuve. She shared her work about the complex viscoelastic behavior of entangled polymer architectures, particularly reversible polymer networks with supramolecular junctions or dynamic covalent bonds. The elasticity of these materials is deeply tied to their intrinsic structure, such as the density of reversible junctions and the size of their molecular building blocks. Meanwhile, relaxation times are mostly influenced by the network’s architecture, including features like dangling ends and entanglements. As expected, the observed behaviors and model predictions are highly sensitive to experimental conditions like temperature and deformation amplitude. If you’re working with associating polymers and want to better grasp their dynamic properties, her work is definitely worth a closer look.
While rheological measurements can be performed with a rheometer under static conditions (bulk measurement), studying complex fluids under microscope, using microfluidics reveals much deeper insights, especially when it comes to biological systems. Flow-induced deformation, stress relaxation, and time-dependent responses offer a more complete understanding of how soft and living materials behave in real-world or physiological environments.
We learned about a promising concept with Matteo Milani from PMMH at ESPCI Paris, that introduced Rheofluidics. This novel technique merges the precision of traditional rheometers with the high throughput of microfluidics. Designed to measure the viscoelastic properties of microscopic objects, such as droplets, vesicles, and hydrogel beads, this method applies well-defined, time-dependent hydrodynamic stresses as droplets flow through specially shaped microfluidic channels. Unlike traditional single-object techniques (e.g. AFM or micropipette aspiration), Rheofluidics enables quantitative rheological measurements at a throughput over 1,000 times greater. The team validated this approach by analyzing both linear and nonlinear rheology of various soft materials, offering a powerful new tool for studying mechanical properties in highly heterogeneous samples.
Vincenzo Ianniello, from ETH Zurich, presented an innovative approach to understanding the mechanical behavior of biofilms. Indeed, they are complex and adaptive materials made of microorganisms embedded in a self-produced extracellular polymeric substance (EPS) matrix. Given the lack of standardized testing methods and the high variability of biofilm properties (influenced by factors like nutrient availability, evaporation, and aging), the team developed a custom experimental setup for more reliable measurements. The biofilm is grown directly on the rheometer to capture its mechanical evolution in real time. A 3D-printed tool, integrated with a syringe pump, ensures continuous nutrient flow and compensates for evaporation, enhancing reproducibility. This setup enables precise measurement of the biofilm’s linear viscoelastic response through interfacial rheology, offering a robust framework for characterizing these highly dynamic biological systems.
Flow control plays a crucial role in additive manufacturing, as we demonstrated in our Application Note on Direct Ink Writing, particularly when working with the extrusion of non-Newtonian fluids. Indeed, simply controlling the flow is not always sufficient for deformable fluids; incorporating pressure feedback can help prevent printing irregularities. At the conference, several studies highlighted the intersection of rheology and additive manufacturing. Notable examples include the work of Mathilde Maillard (Université de Lille) on the printability of ceramics for 3D printing, Guy Della Valle (BIA, INRAE) on plant protein blends for extruded meat analogs, and Nezia de Rosso (CERNN, Brazil) who studied the rheological behavior of sodium alginate for 3D printing applications.
Fabiana Gallo from DICMaPI at the University of Naples Federico II presented an innovative microfluidic approach to assess the deformability of white blood cells (WBCs). Indeed, it is a key parameter that influences their ability to navigate through capillaries or tissues and perform immune functions. Traditional methods like micropipette aspiration or AFM, while accurate, are often slow, costly, and technically demanding. In her work, she uses a flow-focusing microfluidic device with a cross-junction geometry that enables the encapsulation and controlled deformation of individual leukocytes in droplets, allowing real-time observation of their deformation and relaxation under defined stress conditions. Combined with fluorescence imaging and automated analysis, this method provides a fast, scalable, and high-throughput tool for diagnosing immune-related disorders through mechanical cell profiling.
If you’re interested in constriction assays, we recently published a Research Summary using Elveflow instruments to evaluate the stiffness of cardiac spheroids for ischemic tissue models!
As another example of non-Newtonian fluid study, Thomas Podgorski and his collaborators from the Laboratoire Rhéologie et Procédés (Université Grenoble Alpes) presented a microfluidic study exploring how red blood cell (RBC) aggregates break apart under extensional flow using OB1 Flow controller. A condition more representative of what happens in capillaries and bifurcations than traditional shear flow, usually used for hemodynamics analysis. Using hyperbolic microfluidic constrictions and convolutional neural network (CNN) image analysis, the team statistically analyzed aggregate size distributions and dissociation dynamics. Their results showed that beyond a critical extension rate, dissociation rates rise sharply, aligning with microcirculatory stress levels. This work also demonstrated that older RBCs, used as an approximation for aging, form more stable aggregates. Very interesting insights that give more information on the mechanical behavior of RBCs in vivo and highlight the importance of extensional stress in shaping blood flow characteristics in the microvasculature.
At the Annual European Rheology Conference, we observed the widespread use of Micro Particle Image Velocimetry (µPIV) as a powerful tool for analyzing complex fluid flows. Micro PIV is an optical measurement technique used to visualize and quantify fluid flow at the microscale. It works by tracking the motion of small tracer particles suspended in the fluid, using high-speed imaging and laser illumination, to calculate velocity vectors across a microfluidic channel or confined space. Several talks highlighted this technique in a variety of applications:
If you’d like to learn more about this technique for visualizing fluid velocity vectors—and how to integrate it with a microfluidic setup—we invite you to check out our latest research summary on two-phase flow dynamics in a T-junction microchannel!
The addition of particles to a fluid or bulk material inevitably alters its mechanical properties. In some cases, this effect is worth studying to better characterize the material itself; in others, particles are intentionally added to introduce specific functionalities. Below are a few examples of research projects that illustrate these approaches.
In a creative approach to understanding how mechanical forces distribute within tissues, Laura Casanellas from Laboratoire Charles Colomb of University of Montpellier presented her work on biomimetic prototissues, which are simplified tissue models built from Giant Unilamellar Vesicles (GUVs). To detect stress at the microscale, the team incorporated mechano–fluorescent DNA probes, specially designed strands that remain dark under no load but emit fluorescence when stretched, as force separates their complementary bases. By applying localized pressure with nanoindentation tools and observing the system via confocal microscopy, they successfully mapped stress distribution across the tissue-like structures. This method provides a powerful tool for exploring how mechanical forces are transmitted and localized in soft, bioinspired materials.
The study of complex flow also includes the study in various geometries like the hopper. In his work, Jules Tampier, from PMMH in Paris, investigated how dense suspensions of non-Brownian particles flow through a microfluidic hopper, mimicking granular discharge in silos. Unlike liquid flow, granular materials typically exhibit a constant discharge rate independent of fill height—captured by the Beverloo law. In their 2D microfluidic setup, disk-shaped particles are fabricated in situ and driven through a narrow constriction by a pressure gradient, using a flow controller. Surprisingly, despite the fluid medium and pressure-driven flow, the system still exhibited a constant discharge rate, with the outflow well-described by Beverloo-like scaling. The team attributes this behavior to hydraulic resistance governed by the dense particle packing. Their work opens the door for future studies on particles of varying shapes and deformability.
The influence of the elasticity of edible microgel particles on the rheological behavior of dense suspensions was studied by Gabriele D’Oria from INRAE in Paris Saclay. These soft, tunable particles were created using a microfluidic T-junction chip and OB1 flow controller to form water-in-oil (W/O) droplets of whey protein isolate (WPI), which were then gelled by heat treatment. By adjusting the WPI concentration, the elasticity of the resulting microgels could be precisely controlled. Rheological measurements revealed how interparticle interactions and particle elasticity impact the flow behavior under shear. This study not only offers fresh insight into the rheology of soft particle suspensions but also introduces a versatile microfluidic platform for designing particles with tailored mechanical properties.
Microfluidics is an increasingly important technique, even in the world of rheology. Here’s a short list of other talks that featured its use, feel free to explore further if you’re interested in learning more about the research teams behind them.
Arezoo Khakpour (James Weir Fluids Laboratory, University of Strathclyde, Glasgow): “Single-molecule DNA dynamics in microfluidic flows”. Studied DNA stretching and coil-stretch transitions under different flow kinematics using custom microfluidic geometries.
Rheology also has its own universe at the microscale, where precise measurement of the mechanical properties of complex fluids is essential. At Elveflow, we provide highly precise, reliable, and robust instrumentation tailored for such challenges. From our flow controllers to a wide range of flow sensors, pressure sensors, and microfluidic valve systems, our solutions are designed to meet the exact needs of researchers working at small scales. Don’t hesitate to get in touch with our experts—we’ll help you define a setup perfectly adapted to your application.
Our week at the Annual European Rheology Conference (AERC) in Lyon was very fulfilling. From the very first plenary sessions to the poster presentations, we were happy to discover a community pushing the boundaries of what rheology can offer, both in theory and in application. It was a pleasure to see microfluidics take a central role in so many studies, from Rheofluidics enabling high-throughput droplet rheometry, to microfluidic constrictions used for understanding red blood cell aggregation, or the mechanical profiling of biofilms and leukocytes.
We’d like to warmly thank all the researchers, collaborators, and Elveflow users who took the time to visit us during the event, it was a real pleasure to exchange with you directly, hear about your experiments, and discuss how microfluidic tools are helping bring clarity to the complex mechanics of soft and living materials.
This conference confirmed what we believe strongly at Elveflow: rheology at the microscale is a growing frontier, and microfluidics is a key enabler for precise, reproducible, and innovative measurements. Whether you’re working on polymer suspensions, biomaterials, or active matter, we’re here to help you define the best setup—from pressure controllers to flow and pressure sensors, valves, and custom microfluidic chips.
We’re looking forward to supporting both new and long-time users in advancing their research with the power of microfluidics. See you at the next conference!
Written and reviewed by Louise Fournier, PhD in Chemistry and Biology Interface. For more content about Microfluidics, you can have a look here.
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