Plasma Enhanced Attachment of Graphene Dispersed Conductive Polymer to 1D Nanofibers for Sensing and Nanogeneration

Nanogeneration, an emerging area where nanotechnology meets energy harvesting, has the potential to transform how we provide power to our increasingly miniaturized and portable electronic devices. the concept of nanogeneration, which involves the utilization of nanoscale materials and processes to generate electricity from surrounding sources. Nanogeneration encompasses various technologies like piezoelectric nanomaterials, thermoelectric generators, and triboelectric nanogenerators, which make it possible to transform mechanical movements, temperature variations, and even environmental vibrations into electrical power. Polyvinylidene fluoride (PVDF) is a semi-crystalline thermoplastic fluoropolymer known for its remarkable piezoelectric properties. PVDF is a commonly employed material for piezoelectric sensors, serving to measure pressure, force, acceleration, and vibration in various devices. These sensors are applied in industrial monitoring, medical equipment, and consumer electronics. In this study, the Forcespinning® (FS) method was utilized to fabricate PVDF nanofiber mats, which then were cut into small strips for nanogeneration and sensing tests. A conductive polymer ink, composed of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) and graphene nanoflakes, was created and diluted in a 1:1 ratio with deionized water, which was later applied using a dip-coating process on the nanofibers. These nanofibers were initially subjected to a 3-minute plasma etching process to eliminate excessive beading. The specific time was decided after several trials at different times under the plasma treatment, the samples were characterized by Scanning Electron Microscopy (SEM) and it was observed that as the treatment time increased, the finer the fibers became, decreasing the fiber diameter by approximately 500 nm from the pristine nanofibers. The plasma process was done to enhance the adhesion of 2D material particles to the nanofibers, confirmed by SEM. The microscopic images of untreated PVDF nanofibers following the 3-minute plasma treatment displayed a noticeable decrease in the number and dimensions of bead-like structures, along with a substantial reduction of 500 nm in nanofiber diameter. Additionally, the images revealed a strong adhesion between the conductive polymer ink and the nanofibers. Moreover, the coated nanofibers presented an approximate electrical conductivity of 250 kΩ, as well as an average output voltage of 50 mV for single finger pressing, comparable to the work performed by Rahman et al., where a voltage of 75mV was obtained from graphene-coated nanofibers [1]. Further tests for sensing and conductivity of these samples are to be performed, showing a promising advancement for low-powered sensors and energy harvesting.<br/><br/>References:<br/>[1] Rahman, M. A., Rubaiya, F., Islam, N., Lozano, K., & Ashraf, A. (2022). Graphene-coated PVDF/pani fiber mats and their applications in sensing and nanogeneration. <i>ACS Applied Materials & Interfaces</i>, <i>14</i>(33), 38162–38171. https://doi.org/10.1021/acsami.2c09045