Embroidered Active Microwave Composite Preimpregnated Electronics-Pregtronics

The rapid development of the embroidery of conductive threads into textiles and associated biomedical sensors and on-body antennas has given rise to many healthcare and emergency response applications. In this paper, we investigate the embroidery of conductive threads directly into a grade of composites called "preimpregnated" (pre-preg) materials. These pre-preg materials differ from traditional textiles in that they contain a B-staged epoxy resin that must be baked in an autoclave at temperatures greater than 170 degrees C, and under pressures upward of 700 kPa to achieve their maximum strength. The experimental characterization of pre-preg-realized transmission line structures embroidered with different types of threads, stitches, and sewing techniques establishes the best fabrication approaches. Unlike embroidery of conductive threads into textiles, the high processing temperatures and pressures of composite materials result in conductivity and dispersion properties similar to those found in copper. We demonstrate how to incorporate passive and active electronic circuit elements directly into this structural material and its subsequent durability during the hardening process. An embroidered pre-preg electronic (pregtronic) ultrawideband amplifier is realized numerically and confirmed experimentally. Because pre-pregs have a relatively long shelf life when stored within a freezer, as well as the capability to be conformably molded to any surface, the study of pregtronics lends itself to the development of storable, conformal electronics for aerospace, automotive, and other structural applications.