Clevertex - Grado Zero Espace Srl

ergonomic comfort, and high piëzoresistive coefficients, a combination of polypyrrole (PPy) as
conducting polymer and Lycra® as fabric, are used.
Further, a research group at the Intelligent Polymer Research Institute at the University of
Wollongong, Australia, uses intrinsically conductive polymers to coat textile structures. With the use of
conventional textile dyeing equipment they coat textiles with PMAS (Poly(2-methoxyaniline-5-sulfonic
acid)), a water-soluble and commercially available polymer. However, the moderate resistivity restricts
the range of possible applications [33].
Another possibility to achieve in a conductive fabric is to attach a conductive structure to a ground
structure by using the embroidery technique. In 2000, the Massachusetts Institute of Technology
Media Laboratory proposed a way of stitching patterns that can define circuit traces, component
connection pads, or sensing surfaces designed with traditional CAD tools for circuit layout and
rendered on numerically controlled embroidery machines using conducting and insulating threads,
named e-broidery. That allows precisely specifying the circuit layout and stitching pattern in a
computer-aided design (CAD) environment, from which any number of articles can be sewn under
machine control. This process also allows control and integration of yarns with different electrical
properties, for instance, different resistances.
Embroidery offers advantages over knitting or weaving. Conductive thread and yarn embroidery can
be accomplished on single or multiple layers of fabric or can be applied on various types of textile and
apparel products in one step. An example for an embroidered fabric keypad used for a Musical jacket
is given in chapter 2.1.4.1 [11, 34].
Other existing techniques to embed electric circuitry in a fabric include soldering surface-mount
components directly onto metallic organza, bonding components to a substrate using conductive
adhesives, stapling components into a conductive stitched circuit (i.e., pressure-forming their leads to
grip circuit pads), joining a component's “threadframe” directly to a stitched fabric circuit (where
components are formed with a single conductive thread) [34].
Interactive electronic textiles can also be produced by using conductive inks. Conductive inks are
produced by adding metals such as copper, nickel and gold to traditional printing inks. These
specialised inks can be printed onto various materials, among them textiles, to creative electrically
active patterns. The conductive ink technology was originally developed for the production of smart
cards or printed circuit boards, used for example for computer applications, communication,
automotive and industrial electronics. Generally, a distinction can be made between rigid and flexible
printed circuit boards. We will only consider the latter case in this report. The demand for flexible
circuit technology is increasing as electronic and telecommunication devices are becoming more and
16