Janine K. Nunes

Most incoming college students have little awareness of materials science and engineering (MSE) as a discipline, resulting in barriers to entry for a field central to modern technology. To address this gap, we designed a short course curriculum that introduced high school students to MSE concepts through accessible, hands-on, and computationally driven activities framed in the context of chocolate science. The curriculum, rooted in the Context-Based Learning framework, aimed to build scientific literacy and present an engineering perspective by linking everyday observations to the underlying materials science tetrahedron of “structure, process, properties, and performance” relationships. Students engaged in low-cost activities that explicitly connected to advanced laboratory techniques, such as differential scanning calorimetry and polarized optical microscopy, introducing them to tools that produce research-quality data but rely on the same principles. Computational modules introducing Python for modeling, quantitative analysis, and data visualization showed how computational skills can aid broader research efforts and enabled students to produce publication-quality figures and investigate hypotheses. This integrated experimental–computational approach with the chocolate theme lowered barriers to MSE, increased awareness of the field, and empowered students to become citizen scientists.

Effective methods for cleaning surfaces are important for applications including dentistry, healthcare, micro-devices, and the manufacture of electronic components and semiconductors.

In fiber spinning of photopolymers, surface tension limits the diameter of the fiber that can be produced due to the Rayleigh–Plateau instability. Submerging a pre-fiber jet in a miscible environment liberates the system from capillary effects, thus allowing the jet to be stretched into thin threads without instability. In this work, we systematically investigated a spinning method using miscible liquids, called jet-assisted wet spinning (JAWS), where stretching is achieved by a nearby submerged liquid jet. The diameter of the pre-fiber jet is a function of its flow rate and position relative to the assisting submerged liquid jet. A particular case where the main jet is modeled as the Landau–Squire jet is used to demonstrate the tracer-like thinning behavior of the pre-fiber jet. Experiments show that buoyancy has a significant impact on the pre-fiber jet diameter because of its influence on the entrainment trajectory. Overall, our results demonstrate the potential for the parallelization of JAWS for high-throughput fiber production.

The long-time behavior of highly elastic fibers in a shear flow is investigated experimentally and numerically. Characteristic attractors of the dynamics are found. It is shown that for a small ratio of bending to hydrodynamic forces, most fibers form a spinning elongated double helix, performing an effective Jeffery orbit very close to the vorticity direction. Recognition of these oriented shapes, and how they form in time, may prove useful in the future for understanding the time history of complex microstructures in fluid flows and considering processing steps for their synthesis.

There are many fields where it is of interest to measure the elastic moduli of tiny fragile fibers, such as filamentous bacteria, actin filaments, DNA, carbon nanotubes, and functional microfibers. The elastic modulus is typically deduced from a sophisticated tensile test under a microscope, but the throughput is low and limited by the time-consuming and skill-intensive sample loading/unloading. Here, we demonstrate a simple microfluidic method enabling the high-throughput measurement of the elastic moduli of microfibers by rope coiling using a localized compression, where sample loading/unloading are not needed between consecutive measurements. The rope coiling phenomenon occurs spontaneously when a microfiber flows from a small channel into a wide channel. The elastic modulus is determined by measuring either the buckling length or the coiling radius. The throughput of this method, currently 3,300 fibers per hour, is a thousand times higher than that of a tensile tester. We demonstrate the feasibility of the method by testing a nonuniform fiber with axially varying elastic modulus. We also demonstrate its capability for in situ inline measurement in a microfluidic production line. We envisage that high-throughput measurements may facilitate potential applications such as screening or sorting by mechanical properties and real-time control during production of microfibers.

We present an experimental characterization of the gravity-driven Rayleigh-Taylor instability in viscoelastic solids. The instability creates periodic patterns on the free surface of the soft solids that are distinct from the previously studied elastic Rayleigh-Taylor instability. The experimental results are supported by the linear stability analysis reported here. We identify the dependence of the steady-state pattern of deformations on the gel's geometry, complex shear modulus, and surface tension. This study provides quantitative measures applicable to the design of tunable surface textures, soft machines, and 3D structures.

Flows of nonequilibrated aqueous two-phase systems may result in the formation of a 3-dimensional flow field, due to a gradient in tension across the boundary of the two phases.