Previous electrochemically-powered yarn muscles cannot be usefully operated between extreme negative and extreme positive potentials, since strokes during electron injection and during hole injection partially cancel because they are in the same direction. Unipolar-stroke carbon nanotube yarn muscles are described in which muscle strokes are additive between extreme negative and extreme positive potentials, and stroke increases with potential scan rate. These electrochemical artificial muscles include an electrically conducting twisted or coiled yarn and a material that dramatically shifts the potential of zero charge of the electrochemically actuated yarn.

An ion-immobilized metal oxide particle includes a metal oxide particle and an anion that itself includes a) a reactive group that consists of an alkoxysilyl group and b) an anionic group consisting of a carboxylate (COO.sup.) group or a sulfonate (SO.sub.3.sup.) group, the anion being immobilized to the metal oxide particle via a silanol group derived from the reactive group. An elastomer includes the ion-immobilized metal oxide particle, and a transducer includes the elastomer.

Provided are devices and methods that combine material anisotropy with nonlinear structural design to produce structures that precisely and sequentially actuate in response to multiple stimuli, such as water or non-polar solvents. These devices and methods can include bistable anisotropic elements that convert to monostable element upon exposure to a particular stimulus, and anisotropic distortions can be harnessed to change the geometric properties of the element to cross phase boundaries and trigger shape changes at precise times. One can incorporate complex logic into these devices and methods.

Apparatuses for utilizing transient pressures inherent in water mains to generate electrical power and methods of using the same. A solid-state energy harvester device comprises a cylindrical body configured to be installed inline with a fluid-carrying pipe system and defining a fluid path, a flexible sleeve disposed inside the cylindrical body and encompassing the fluid path, and a plurality of piezoelectric elements integrated into the flexible sleeve. The cylindrical body, flexible sleeve, and plurality of piezoelectric elements are configured such that transient pressures in the fluid flowing through the fluid path cause the flexible sleeve to flex and bend, exciting the plurality of piezoelectric elements to produce an electric current.