| Stretchable electronics is a promising field for biomedical applications. Stretchable devices can be used for various purposes, including wearable electronics (or smart clothes), artificial skin, and more generally for any purpose requiring to have on-skin electronics that conform to the lifestyle of the patient, for example day-by-day biomonitoring. Many strategies have been used so far to produce stretchable electronics, however these can be split between two main categories. In the first one are the materials that stretch due to a specific geometry, while in the second category are the materials that are intrinsically stretchable. Specific shapes such as fibers can thus be used to improve the stretchability of an otherwise poorly-stretchable material, including conductive materials such as metals or conducting and semi-conducting polymers used in organic electronics. However, the practical application of fibers in stretchable electronics requires the use of a technique that can easily yield conductive fibers. For biological applications, organic electronic materials present the advantage over conventional electronic materials to possess a good compatibility with biological systems due to their ability to easily interface with the biological milieu and their mixed ionic / electronic conduction.;The objective of this research project is to demonstrate the fabrication of such films, made with conductive polymer nanofibers that can still conduct the current even when stretched.;Although many methods exist to produce such fibers, electrospinning is one of the easiest ways to directly make non-woven porous nanofiber mats that can conform to the surface of their substrate. By combining electrospinning with vapor phase polymerization, we fabricated conductive nanofibers of poly-(3,4-ethylenedioxythiophene) doped with paratolenesulfonate (tosylate, PEDOT:Tos) directly on polydimethylsiloxane (PDMS), an organosilicon elastomer. Non-woven fiber mats composed of conductive nanofibers with an average diameter of around 700 nm were obtained directly on PDMS. We characterized these fibers to study their electrical behavior when a strain was applied to them. These mats were then stretched while the current flowing inside them was measured, at fixed voltage. This allowed us to demonstrate a stretchability up to 140% of the initial length without major variation of the current flowing in the mats. |
