Multimaterial fiber electronics

Abstract

As the number of materials that are thermally-drawable into fibers is rapidly expending, numerous new multimaterial fiber architectures can be envisioned and fabricated. High-melting temperature metals, compound materials, composite, conductive or ferroelectric polymers: the broad diversity of these materials' nature and properties, combined with various post-fabrication treatments recently developed (poling, annealing, injection, coating, capillary breakup), enable the making of novel in-fiber, stand-alone-fiber and fiber-array devices. In this thesis, we demonstrate a wide variety of novel multimaterial fiber capabilities at all these levels, focusing specifically on new electronic functions. First, the implementation of conductive polymer as in-fiber current buses is shown to enable distributed light sensing and modulation along a single fiber, by inducing transmission-line effects in d.c. and a.c. operation. Next, the design and operation of a photosensing fiber specially treated to detect explosives is presented, and the sensitivity of this fiber device is shown to meet state-of-the-art industry standards. A novel large-interface-area design for dielectric fibers is then presented, which enables both energy storage in flexible fiber capacitors as well as enhanced acoustic transduction in piezoelectric fibers. The flexibility as well as the assembly into arrays of the latter are shown to enable the shaping of a pressure field in all three dimensions of space. Finally, a novel thermal-gradient capillary breakup process for silica-based fibers is shown, enabling the fabrication of silicon-in-silica micro spheres and rectifying devices. Taken as a whole, these new capabilities greatly expand the breadth of functionality of multimaterial fibers, further paving the way towards highly multifunctional, wholly integrated electronic fiber devices and fabrics that can collect, store and transduce energy in all of its forms.