Guide structure with pole arrays imprinted on nylon fiber

Abstract

For the next generation of micro–electro-mechanical-systems (MEMS) with flexibility and large size, we are developing new kinds of MEMS that will be woven fabric of “on-fiber-devices”. An on-fiber-device is realized by thin-film-coating, patterning, and etching on the surface of a thin fiber that is then transformed into fiber-shaped device to make MEMS such as sensors and actuators. These on-fiber-devices that themselves are in shape of fibers are woven and criss-crossed resulting in new devices with novel functions. The contact points, interconnecting the woven fibers are designed to be fixed with respect to each other where they can make electrical contacts as necessary. We have developed a thermal nanoimprint technology to fabricate weaving guide structures supporting electric contact points on the surface of a thin fiber. The cross-sectional shape of the weaving guide structure was made to be rectangular, and arrays of cylinder poles of 5, 10 and 20 μm in diameters were arranged as supporting structures for making electrical contacts with the bottom of the weaving guide structure. A mold for this purpose required a two-step structure capable of imprinting weaving guide structure, and the contact points on the surface of a fiber in one stamping operation. Such a mold was fabricated by combining MEMS processing with Ni-electroforming technology. Four kinds of guide structures with depths of 20, 30, 40 and 50 μm were processed by adjusting the dry-etching during the making of a Si master. Using these electroformed-Ni molds, these different weaving guide structures, each with a set of 5-, 10- and 20-μm diameter cylinder poles were transferred onto a 90-μm diameter nylon fiber by thermal imprinting.