A three-dimensional object comprises stacked substrate layers infiltrated by a hardened material. Each substrate layer is a sheet-like structure that comprises fibers held together by a sodium silicate binder. The substrate layer material may be non-woven or woven. The substrate layer may be a non-woven fiber veil bound by a sodium silicate binder. The fibers may optionally include carbon fibers, ceramic fibers, polymer fibers, glass fibers, metal fibers, or a combination thereof.

A method for preparing a fully soft self-powered vibration sensor mainly uses a laser carbonization technology to prepare a two-dimensional porous carbon electrode with an origami structure, and then transfers the two-dimensional porous carbon electrode to a three-dimensional polydimethylsiloxane (PDMS) cavity through mold transfer; finally, a laser engraving technology is used to create microstructures on surfaces of the porous carbon electrode and a PDMS film. The sensor includes the PDMS film, a liquid metal droplet oscillator, a porous out-of-plane carbon electrode, and a 3D PDMS cavity assembled tightly from top to bottom. The sensor works based on the triboelectric nanogenerator principle, when the sensor is excited by vibrations, contact and triboelectrification at an interface of the liquid metal droplet oscillator and PDMS film charge both objects, making contact surfaces carry stable charges, which allows the movement of the liquid metal droplet oscillator to output current through electrostatic induction.

A three-dimensional object comprises stacked substrate layers infiltrated by a hardened material comprising engineered powder that is transformed into a substance that flows and subsequently hardens into the hardened material in a spatial pattern that infiltrates positive regions, and does not infiltrate negative regions, in the substrate layers. The powder may be emulsion aggregation powder, chemically-produced toner powder, or a combination. It may be a thermoplastic or thermosettable polymer and may include nylon, elastomers, polyolefins, polyethylene, polyether ether ketone, polyimide, polyetherimide, polyphenylene sulfide, polystyrene, polypropylene, polymethyl methacrylate, and polyaryletherketone, or a combination. The powder particles may have a pre-specified controlled shape and/or a non-homogenous composition. Surface treatments and/or additives may be used to control powder flow and charge distribution. Each substrate layer may be a sheet-like structure comprising fibers held together by binder. The binder may include sodium silicate.

A process for producing a stable fabric comprising: 1) providing a first fabric formed from reinforcing fibers, 2) providing an elastic nonwoven web produced from elastic fibers, having softening temperature lower than said reinforcing fibers, on at least 1 one side of said first fabric to form a structure, 3) heating said structure to a temperature between the softening temperature and melting temperature of said nonwoven web, and 4) cooling said structure to thereby provide a stable two-dimensional fabric. In the preferred embodiment, the structure of step 2) is put into a mold prior to heating step 3), heating said structure in the mold according to step 3), cooling said structure in the mold according to step 4) and thereby providing a three-dimensional shaped article. A product is also provided produced by these processes.