The authors have proposed electrical circuits accumulated by injecting electroconductive materials into patterns imprinted on the surface of fibers and weaving the fibers like a mesh. For these circuits, a built-in guide structures, which determine the positions where the fibers are to make contact with each other and exchange pertinent information, must be fabricated on fibers. In the experiments, a concave 21-mu m-deep structure to serve as weaving guide was processed on the surface of 90-mu m-diameter nylon fibers by thermal imprinting with a plane mold. The guides were made with two types of cross sections: rectangular and arc shaped. The rectangular structure was fabricated by a combination of microelectromechanical systems processing and Ni-electroforming technologies, whereas the arc-shaped structure involved dicing and fine machining operations. These structures on molds were designed to imprint weaving-guide structures on fibers with arrays of poles (20 mu m in diameter and 10 mu m in height) at their bottom to serve as fixation points for fibers and to make electric contacts after metallization. Both types of molds were made with a two-step structure that could be transferred on fibers in one single stamping operation. In thermal imprint experiments, to speed things up, the contact time was set for 1 s only. In order to compensate for the short contact time, the heating temperature was set at 100 degrees C, which is 50 degrees C higher than the glass transition temperature of nylon. Regardless of the type of mold, weaving guides and contact supports were successfully formed on the surface of nylon fibers. Thus, the capability to process complex microstructures by thermal nanoimprinting on the surface of fine fibers was experimentally proven. Moreover, the authors report on the results of the trial run for weaving imprinted nylon fibers to form fabrics. (C) 2010 American Vacuum Society. [DOT: 10.1116/1.3386586]