The handling of chemicals in the laboratory presents a challenge in instructing large class sizes and when students are relatively new to the laboratory environment. In this work, we describe and demonstrate an augmented reality colorimetric titration tool that operates out of the smartphone or tablet of students. It allows multiple students to conduct the exercise at the same time, respond quickly to actions made, and correctly depict the colors associated with changes in pH values for the indicator used. The tool imbues unparalleled realism in the conduct of the experiment and offers to strongly help students acquire bench skills with minimal use of liquid chemicals, thereby reducing handing risks for them and resulting in lower negative impacts on the environment. The feedback received from undergraduate students that participated in an initial small test exercise with the tool corroborates this.

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Computational and theoretical models of millimeter-sized bubbles placed on upright hydrophobic and superhydrophobic surfaces are compared with experimental data here. Although the experimental data for a hydrophobic surface corroborated the computational and theoretical data, the case of a superhydrophobic surface showed the bubbles to be able to contain significantly larger volumes than predicted. This is attributed to the greater ability of the bubble contact line to advance compared with its tendency to detach from the surface because of buoyancy. We surmise that a static model therefore describes only an unstable equilibrium for these bubbles, which unless heavily isolated from external influences are more likely to assume a larger stable size.

Properly controlling the rheological properties of nanoparticle inks is crucial to their printability. Here, it is reported that colloidal gels containing a dynamic network of graphene oxide (GO) sheets can display unusual rheological properties after high‐rate shearing. When mixed with polyaniline nanofiber dispersions, the GO network not only facilitates the gelation process but also serves as an effective energy‐transmission network to allow fast structural recovery after the gel is deformed by high‐rate shearing. This extraordinary fast recovery phenomenon has made it possible to use the conventional air‐brush spray technique to print the gel with high‐throughput and high fidelity on nonplanar flexible surfaces. The as‐printed micro‐supercapacitors exhibit an areal capacitance 4–6 times higher than traditionally spray‐printed ones. This work highlights the hidden potential of 2D materials as functional yet highly efficient rheological enhancers to facilitate industrial processing of nanomaterial‐based devices.

In the laminar flow regime which characterizes the operation of most microfluidic systems, mixing is governed primarily by molecular diffusion. An increase in the interfacial surface between the fluids contained in the system facilitates the mixing process. This can be obtained by active external perturbation, requiring complex systems and complex operation, or passively by clever design over the geometrical constraints. Here, we describe an active micromixer technique based on the excitation of vortices in proximity to sharp corners of junctions, as a result of simple low frequency vibration of the device. Results showing the working principle in both static and fluid through conditions are presented.