Development of reel-to-reel process system for roller-imprint on plastic fibers

Abstract

We are developing a woven fabric of micro-electro-mechanical-systems (MEMS) where smart fibers are woven to make large-size flexible devices. MEMS structures and electric circuits are formed on the surface of individual fibers to serve as smart fibers where they can function as sensors and actuators. Moreover, when smart fibers are inter-woven it becomes necessary to process electric contact and physical positioning guides on the surfaces of warp and woof fibers. To transfer various patterns on the surface of a fiber at high speed, a batch process by thermal nanoimprinting is pursued. We then developed a new-type roller nanoimprint system to precisely transfer fine patterns from a plane mold onto the curved surface of a fibrous substrate. In this system, a fiber is sandwiched by two molds and rolls under the traction force of sliding molds traveling in opposite directions. At the end of their travel the molds are separated. The molds are moved in directions opposite to their previous directions of travel. This brings the molds back to their inital positions. Then, the fiber is moved by a preset distance using a reel-to-reel feeder. A new cycle starts again. With this method, 5-μm-width square and 5-μm-diameter circular dotted patterns with 10μm pitch were successfully transferred onto a 250-μm-diameter plastic optical fiber (POF) covering its full surface. Moreover, we succeeded in a continuous molding on the entire curved surface of 1.6m long POF using a reel-to-reel feeder as a batch processing operation with a pitch of 16mm by a repetition of roller-imprinting for 100 times. No significant difference was observed when the shapes and depths of the imprinted patterns obtained from the first imprinting were compared with those of obtained from the 100th imprinting.