A microfluidic electrochemical reactor includes an electrode and one or more microfluidic channels on the electrode, where the microfluidic channels are covered with a membrane containing a gas permeable polymer. The distance between the electrode and the membrane is less than 500 micrometers. The microfluidic electrochemical reactor can provide for increased reaction rates in electrochemical reactions using a gaseous reactant, as compared to conventional electrochemical cells. Microfluidic electrochemical reactors can be incorporated into devices for applications such as fuel cells, electrochemical analysis, microfluidic actuation, pH gradient formation.
Methods and apparatus for storing information or energy. An array of nano vacuum tubes is evacuated to a pressure below 10.sup.-6 Torr, where each nano vacuum tube has an anodic electrode, a cathodic electrode spaced apart from the anodic electrode, and an intervening evacuated region. An excess of electrons is stored on the cathodic electrode.