High-throughput rheology in a microfluidic device


High-throughput rheological measurements in a microfluidic device are demonstrated. A series of microrheology samples are generated as droplets in an immiscible spacer fluid using a microfluidic T-junction. The compositions of the sample droplets are continuously varied over a wide range. Rheology measurements are made in each droplet using multiple particle tracking microrheology. We review critical design and operating parameters, including the droplet size, flow rates and rapid fabrication methods. Validation experiments are performed by measuring the solution viscosity of glycerine and the biopolymer heparin as a function of concentration. Overall, the combination of microrheology with microfluidics maximizes the number of rheological measurements while simultaneously minimizing the sample preparation time and amount of material, and should be particularly suited to the characterization of scarce or expensive materials.

For Lucas

Nanowired three-dimensional cardiac patches

Engineered cardiac patches for treating damaged heart tissues after a heart attack are normally produced by seeding heart cells within three-dimensional porous biomaterial scaffolds^{1, 2, 3}. These biomaterials, which are usually made of either biological polymers such as alginate⁴ or synthetic polymers such as poly(lactic acid) (PLA)⁵, help cells organize into functioning tissues, but poor conductivity of these materials limits the ability of the patch to contract strongly as a unit⁶. Here, we show that incorporating gold nanowires within alginate scaffolds can bridge the electrically resistant pore walls of alginate and improve electrical communication between adjacent cardiac cells. Tissues grown on these composite matrices were thicker and better aligned than those grown on pristine alginate and when electrically stimulated, the cells in these tissues contracted synchronously. Furthermore, higher levels of the proteins involved in muscle contraction and electrical coupling are detected in the composite matrices. It is expected that the integration of conducting nanowires within three-dimensional scaffolds may improve the therapeutic value of current cardiac patches.

The washable wearable antenna

ESA has provided research and development guidance to Finnish company Patria, with the help of Tampere University of Technology, in designing a search and rescue radio antenna that can be sewn into a life vest.

Wireless Solar Water Splitting Using Silicon-Based Semiconductors and Earth-Abundant Catalysts

We describe the development of solar water-splitting cells comprising earth-abundant elements that operate in near-neutral pH conditions, both with and without connecting wires. The cells consist of a triple junction, amorphous silicon photovoltaic interfaced to hydrogen and oxygen evolving catalysts made from an alloy of earth-abundant metals and a cobalt|borate catalyst, respectively. The devices described herein carry out the solar-driven water-splitting reaction at efficiencies of 4.7% for a wired configuration and 2.5% for a wireless configuration when illuminated with 1 sun of AM 1.5 simulated sunlight. Fuel-forming catalysts interfaced with light-harvesting semiconductors afford a pathway to direct solar-to-fuels conversion that captures many of the basic functional elements of a leaf.