Soft Memristor at a Microbubble Interface.

Memristors show promising features for neuromorphic computing. Here we report a soft memristor based on the liquid-vapor surface of a microbubble. The thickness of the liquid film was modulated by electrostatic and interfacial forces, enabling resistance switches. We found a pinched current hysteresis at scanning periods between 1.6 and 51.2 s, while representing a resistor below 1.6 s and a diode-like behavior above 51.2 s. We approximate the thickening/thinning dynamics of liquid film by pressure-driven flow at the interface and derived the impacts of salt concentration and voltage amplitude on the memory effects. Our work opens a new approach to building nanofluidic memristors by a soft interface, which may be useful for new types of neuromorphic computing in the future.

Colloid, interface, and foam properties of water-soluble polyglycerol esters solutions.

HYPOTHESIS: Polyglycerol esters of fatty acids are generated via the esterification of a polydisperse mixture of polyglycerol with naturally derived fatty acids. The polymerization process of polyglycerol results in the production of various oligomers, ranging from di-, tri-, and higher-order forms, which contribute to the complexity of final products. The combination of complementary experimental techniques and adequate theoretical interpretations can reveal the wide variety of their physicochemical properties. EXPERIMENTS: The colloid and interface properties of polyglyceryl mono-laurate, mono-stearate, mono-oleate, and a mixture of mono-caprylate and mono-caprate esters solutions were characterized by measurements of the electrolytic conductivity, static and dynamic surface tension, aggregate and micelle sizes and distributions, thin liquid film stability and stratification, and solubility in aqueous and in oil phases. The formation, stability, and bubble size distribution of foams generated from polyglycerol esters aqueous solutions were systematically investigated. FINDINGS: The low concentrations of double-tail molecules and fatty acids in polyglycerol esters affect considerably their micellar, aggregation, and vesicle formations in aqueous solutions. The theoretical data interpretation of polyglycerol esters isotherms and thin liquid films data provide information on the adsorption energies, excluded areas per molecule, interaction parameters of molecules at interfaces, surface electrostatic potential, and the size of micelles. Polyglyceryl mono-oleate exhibits spontaneous emulsification properties. Short chain length polyglycerol esters have excellent foaming ability but relatively low foam stability. The optimal weight fractions of the short-chain polyglyceryl esters and polyglyceryl mono-stearate mixtures with respect to good foaminess and foam stability upon Ostwald ripening are obtained. The reported physicochemical characterization of the water-soluble polyglycerol esters could be of interest to increase the range of their applicability in practice.