THE FRUGAL LAB

We are a curiosity-driven lab which research focuses on the mechanics of complex fluids and solids.

Often inspired by Nature and biology, we explore the physics of how droplets spread and move super fast on rough and superhydrophilic surfaces, how cut and folded surfaces can morph in an unexpected 3D shapes,...

Our general strategy is to strive for fundamental understanding of unexpected natural, biological and physical phenomenon and to exploit our research findings to develop ingenious and frugal solutions to societal problems.

In our lab, we explore and develop basic principles behind unconventional water collection system using fog nets.

OUR APPROACH

  • Bio-inspiration - Our research process often starts with a biological inspiration as Nature is a world of fascinating strategies and ideas.
  • Digital Fabrication - We use advanced digital fabrication tools that can be found in Fablabs such as 3D printers, laser cutters, CNC milling,... to fabricate our experimental setups and scientific tools.
  • Rapid Prototyping - We rapid prototype and build well-controlled experiments in very precise and affordable ways that are often reproducible in any fablab environment.
  • Model Experiments - To tackle these physics issues, we design and explore model experiments i.e. “synthetic analogs” that we characterize using Soft Matter tools and that allows us to easily interact with experiments and to enhance our physics insight.
  • The Frugal Way - simplifying a problem to its simplest essence (but not simpler) increases clarity and makes is more fit to be shared broadly and empowers people.

OUR WORK AND ACTIVITIES

Academic Research

[Research] Optimization of Fog Nets

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Our goal is to improve the recovery of aerial freshwater using fiber networks, and following physical processes inspired by the plant kingdom.

[Research] Wetting of fibres

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In this work, we deposit different liquids on different fiber arrays. Depending on the nature of the liquid and the fibers as well as the geometry, we explore the criterion for penetration of the drops through the fibers. Indeed according to this criterion, a drop deposited on the surface of the fiber arrangement can remain on its surface or pass through.

[Research] Shape and movement of evaporating bi-composed droplet

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When two-components drops of Propylene Glycol and water are deposited on a surface of high energy, these drops take the surprising form of a sessile drop. In this work, using an experimental and theoretical interferometric study we highlight the importance of the shape of the droplet foot on the shape and movement of these drops due to Marangoni effects.

[Research & Teaching] Mechanical Meta Materials

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Mechanical metamaterials are materials that have unusual mechanical properties thanks to their structure rather than their microscopic composition. Digital fabrication has recently given the tools to physicists, mathematicians, engineers and designers to explore these kinds of new materials. These smart materials open the path to materials in which we can pre-program the way they deform or they behave.
  • [Workshop activity] Digital Mechanical Material by Design, a physicist approach,
    Fab14 Conference, Toulouse, Frances 2018 (website)

[Research] Morphing surfaces leading to aerodynamic drag control

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Smart Morphable Surfaces enable switchable and tunable aerodynamic drag reduction of bluff bodies. Their topography, resembling the morphology of golf balls, can be custom-generated through a wrinkling instability on a curved surface. Pneumatic actuation of these patterns results in the control of the drag coefficient of spherical samples by up to a factor of two, over a range of flow conditions.

[Research] Wrinkling crystallography on spherical surfaces

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Curved crystals cannot comprise hexagons alone; additional defects are required by both topology and energetics that depend on the system size. Treating dimples, generated through curved wrinkling, as point-like packing units, we show that our system can be mapped into and described within the framework of curved crystallography, albeit with some important differences attributed to the far-from-equilibrium nature of our patterns.
  • [Research Paper] M. Brojan, D. Terwagne, R. Lagrange and P. M. Reis, “Wrinkling crystallography on spherical surfaces”, Proc. Natl. Acad. Sci. U.S.A., 112, 14, 2015. [html, pdf]

[Research] Curvature-induced symmetry breaking determines the wrinkling pattern

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The wrinkling morphologies of our curved elastic bilayer materials are further analyzed in collaboration with a team from the Math department of MIT. The pattern formation is described here by deriving a generalized Swift-Hohenberg theory. This theory, universally applicable to macroscopic and microscopic systems, can be extend to arbitrarily shaped surfaces, thereby solving a longstanding problem in elasticity theory.

[Research] Curvature-induced symmetry breaking determines the wrinkling pattern

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Inspired by the morphology of growing plant roots and compressed microtubules in cells, our team from MIT devised a model experiment to study, in collaboration with a team of Harvard University, the multi-dimensional buckling of fibers in an elastic matrix. This latter research could open opportunities for functionality by generating complex 3D shapes, reversibly and on-demand.
  • [Research Paper] S. Tianxiang, J. Liu, D. Terwagne, P. M. Reis and K. Bertoldi, “Buckling of an elastic rod embedded on an elastomeric matrix: planar vs. non-planar configurations”, Soft Matter, 10, 6294, 2014. [html, pdf]

[Research] Bouncing droplets resonant modes

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To enhance the bouncing droplet deformation we consider a low viscosity droplet on a high viscosity bath. Depending of the excitation frequency, different deformation modes appear. Theoretically, these modes correspond to spherical harmonics Y(l,m).
  • [Research Paper] S. Dorbolo, D. Terwagne, N. Vandewalle and T. Gilet, “Resonant and rolling droplets”, New J. Phys. 10, 113021, 2008. [html, pdf]
  • [Research Paper] D. Terwagne, F. Ludewig, N. Vandewalle and S. Dorbolo, “The role of the droplet deformations in the bouncing droplet dynamics”, Phys. Fluids 25, 122101, 2013. [html, pdf]

[Research] The singing bowl

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The Tibetan singing bowl is a type of standing bell originating from Himalaya. A singing bowl is played by striking or rubbing its rim with a wooden or leather-wrapped mallet. The sides and rim of the bowl then vibrate to produce a rich sound. When the bowl is filled with water, this excitation can cause crispation of the water surface that can be followed by more complicated surface wave patterns and ultimately the creation of droplets. We present here an extensive investigation of the acoustics and the fluid dynamics of the bowl.

[Research] Microfluidic on a wire

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Using simple fiber networks, elementary microfluidic operations with droplets are performed, such as coalescence, division, encapsulation and chemical reactions by adjusting gravity and capillary forces.
  • [Research Poster] Summary on a poster presented at the American Physical Society, Division of Fluid Dynamics at Mineapolis in November 2009.
  • [Research Paper] T. Gilet, D. Terwagne and N. Vandewalle, “Digital microfluidics on a wire”, Appl. Phys. Lett. 95, 014106, 2009. [html, pdf]
  • [Research Paper] T. Gilet, D. Terwagne and N. Vandewalle, “Droplet sliding on fibres”, Eur. Phys. J. E 31, 253, 2010. [html, pdf]

[Research] Frozen splashes

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When a droplet impacts a dry granular bed, it creates all sorts of dry and stable structures after impact that looks like donuts, pancakes or complex blobs. These are frozen “splashes”. Depending on the impact speed, the droplets wet the sand and shape it before being sucked by the granular bed underneath.
  • [Research Paper] G. Delon, D. Terwagne, S. Dorbolo, N. Vandewalle and H. Caps, “Impact of liquid droplets on granular media”, Phys. Rev. E 84, 046320, 2011. [html, pdf]

Open-Source Lab

Teaching & Outreach

[Teaching] Fablab Studio

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Facing an uncertain and rapidly changing future, Fablabs are a great environment to teach social and technical skills that are relevant for the 21st century.

At Fablab ULB, Victor Lévy, professor of architecture and Denis Terwagne, professor of physics, are experiencing and developing an agile teaching method to make students work with digital tools in interdisciplinary teams and to make a real-world impact.

Starting with a "real world" problem, we guide the students to define their own assignment. To run the class, we use collective intelligence and tools from sociocracy. We help the students to use the digital tools within a Fablab and have a conversation with authentic audiences from all around the world.

[Teaching & Outreach] Fab Academy

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To share our culture, values and our work and being part of Fablab ULB, we are active in the Fablab network through the Fab Academy and Fabricademy. Fab Academy The Fab Academy , initiated by Prof. Neil Gershenfeld professor at the MIT CBA, is a 6 months, fast paced, hands-on learning experience where students learn rapid-prototyping by planning and executing a new project each week, resulting in a final project and a personal portfolio of technical accomplishments.

[Teaching] Soft Matter Physics - flipped classroom

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This class concerns the study of Soft Condensed Matter Physics for 3rd year physics students.

Soft Structures and Surfaces

OUR TEAM

Since 2019, FrugalLab team is part of an interdisciplinary research team embedded in our university FabLab ULB.

The Fablab ULB team is composed of scientists, engineers, architects, lawyers, ... which aims to act on the world and which recognize the necessity of addressing tomorrows challenge collectively and multidisciplinary.

"Immersed in the third digital revolution, we are exploring how digital fabrication is changing the way we make things, we come and work together in order to guide our society to stay on top of a fast changing world."

OUR WORKSPACE

The lab is located on the new and vibrant ULB-VUB Usquare Campus in Brussels within the FabLab ULB.

The lab is embedded in a making culture and an interdisciplinary environment that allows to deal with research questions beyond individual disciplines (Science, Architecture, Engineering, Law).