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Living materials combine a material scaffold, that is often porous, with engineered cells that perform sensing, computing, and biosynthetic tasks. Designing such systems is difficult because little is known regarding signaling transport parameters in the material. Here, the development of a porous microplate is presented. Hydrogel barriers between wells have a porosity of 60% and a tortuosity factor of 1.6, allowing molecular diffusion between wells. The permeability of dyes, antibiotics, inducers, and quorum signals between wells were characterized. A "sentinel" strain was constructed by introducing orthogonal sensors into the genome of Escherichia coli MG1655 for IPTG, anhydrotetracycline, L-arabinose, and four quorum signals. The strain's response to inducer diffusion through the wells was quantified up to 14 mm, and quorum and antibacterial signaling were measured over 16 h. Signaling distance is dictated by hydrogel adsorption, quantified using a linear finite element model that yields adsorption coefficients from 0 to 0.1 mol m-3 . Parameters derived herein will aid the design of living materials for pathogen remediation, computation, and self-organizing biofilms.

Viscous fingering is a widely observed phenomenon, in which finger-like instabilities occur at the interface of two fluids, whenever a less viscous phase displaces a more viscous phase. This instability is notoriously difficult to control, especially for given viscosity ratio and geometry. Here we demonstrate experimentally the active control of viscous fingering of two given liquids, for given geometry and flow rate in a Hele-Shaw cell. The control is realized by taking advantage of electro-osmotic flows along the surfaces confining the fluid, via applying an external electric field. Depending on the direction of electric field, the induced secondary electro-osmotic flows either assist or oppose the hydraulic flow, effectively reducing or increasing the flow resistance, leading to the control of interface stability. The mechanism of apparent “electrokinetic thinning/thickening” is proposed to explain the experimental observations. Theoretical predictions of linear stability are confirmed experimentally for a broad range of immiscible electrolyte displacements. ©2019, The Author(s).

We propose and demonstrate a novel flow battery architecture that replaces traditional ion-exchange membranes with less expensive heterogeneous flow-through porous media. Compared to previous membraneless systems, our prototype exhibits significantly improved power density (0.925 W cm[superscript -2]), maximum current density (3 A cm[suprescript -2]), and reactant crossover, shown by the proposed experimentally-validated crossover model.

Redox flow batteries (RFBs) are one of the most promising scalable electricity-storage systems to address the intermittency issues of renewable energy sources such as wind and solar. The prerequisite for RFBs to be economically viable and widely employed is their low cost. Here we present a new zinc–iron (Zn–Fe) RFB based on double-membrane triple-electrolyte design that is estimated to have under $100 per kW h system capital cost. Such a low cost is achieved by a combination of inexpensive redox materials (i.e., zinc and iron) and high cell performance (e.g., 676 mW cm[superscript −2] power density). Engineering of the cell structure is found to be critical to enable the high power density. Our cost model shows that a Zn–Fe RFB demonstrates the lowest cost among some notable RFBs and could reach the 2023 cost target set by the U.S. Department of Energy ($150 per kW h)., United States. Dept. of Energy (ARPA-E Award DE-AR0000346)