Reel-to-reel imprint system to form weaving guides on fibers

Abstract

Graphical abstractDisplay Omitted Highlights? We developed a reel-to-reel imprint system to process a fiber using a cylindrical mold. ? A press force correction mechanism that suppressed the installation error was built. ? Continuous pressing with a constant force was enabled at a sending speed of 5m/min. ? We succeeded in thermal-imprinting of weaving guides on the surface of a plastic optical fiber. We developed a reel-to-reel imprint system using a cylindrical mold that could continuously process a uniform-depth microstructure on the surface of a fibrous substrate. A fiber coming out from a sending reel was placed between two rotating heated cylindrical molds under a moderate press-force, and was then fed into a receiving reel. The two cylindrical molds rotated in opposite directions to each other while synchronized with the rotations of the two reels that moved the fiber from the sending reel to the receiving reel. The cylindrical molds comprised 100-mm-diameter metal cylinders covered with a Ni electroless-plated layer on which convex mold patterns were fabricated using a high-precision machining tool. The system was equipped with a press-force control mechanism capable of adjusting the gap between the two cylindrical molds in rapid response to any variation in the press-force as detected by a load cell. This mechanism suppresses any fluctuation in the press-force that may occur due to any error made during the assembling of the cylindrical mold. This setup can also make continuous imprinting possible under a constant force. By adjusting the cylindrical mold's position within a 74-µm-wide range, the fluctuation of the press-force can be reduced from 33 to 3N. Furthermore, as a demonstration, a plastic optical fiber (POF) in a diameter of 250µm was sent at speeds of 1m/min and 5m/min; and by a continuous imprinting process, 260-µm-wide rectangle-shape, and 145-µm-radius arc-shape concave microstructures were formed on the surface of the POFs. When the sending speeds were 1 and 5m/min, the maximum standard deviations of the imprinted depths were estimated to be 0.52 and 0.14µm, respectively. These values fell within 17% of the POF's diameter variations of 3µm. The imprinted fibrous substrate will be used as fibers that constitute e-textiles; and the imprinted concave microstructures will be used as weaving guides to fix the contact positions between warps and wefts.