Fabrication and characterization of conducting polymer microwires

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2009.Cataloged from PDF version of thesis.Includes bibliographical references (p. 91-94).Flexible microwires fabricated from conducting polymers have a wide range of potential applications, including smart textiles that incorporate sensing, actuation, and data processing. The development of garments that integrate these functionalities over wide areas (i.e. the human body) requires the production of long, highly conductive, and mechanically robust fibers or microwires. This thesis describes the development of a microwire slicing instrument capable of producing conducting polymer wires with widths as small as a few micrometers and lengths ranging from tens of millimeters to meters. To ensure high conductivity and robustness, the wires are sliced from thin polypyrrole films electrodeposited onto a glassy carbon crucible. Extensive testing was conducted to determine the optimal cutting parameters for producing long, fine wires with cleanly cut edges. This versatile fabrication process has been used to produce free-standing microwires with cross-sections of 2 [micro]m x 3 [micro]m, 20 [micro]m x 20 [micro]m, and 100 [micro]m x 20 [micro]m with lengths of 15 mm, 460 mm, and 1,200 mm, respectively. An electrochemical dynamic mechanical analyzer was used to measure the static and dynamic tensile properties, the strain-resistance relationship, and the electrochemical actuation performance of the microwires. The measured gage factors ranged from 0.4 to 0.7 and are suitable for strain sensing applications. Strains and forces of up to 2.9% and 2.3 mN were recorded during electrochemical actuation in BMIMPF6 . These monofilament microwires may be spun into yarns or braided into 2- and 3- dimensional structures for use as actuators, sensors, micro antennas, and electrical interconnects in smart fabrics.by Miguel Angel Sáez.S.M