Development of Flexible Pressure Sensing Assembly of Biodegradable Polymers and Nanocomposite

Abstract

The wearable and flexible pressure sensors have gained significant attention due to their capability of transducing the physical phenomena like pressure and temperature into electrical signals. This study assessed the feasibility of poly(L-lactide) (PLA) nanocomposite films prepared by the solvent evaporation method and integrated it with knitted cotton fabric for pressure sensing application. Multiwalled carbon nanotubes (MWCNT), graphene oxide (GO), and carbon black (CB) individually and in a tri-mixture were used as nanofillers to improve the electrical conductivity of 2 wt.% PLA film. The increasing loadings of nanomaterials (0.1–8 wt.% for individual and 1–5 wt.% for tri-mixture) improved the electrical conductivity of PLA nanocomposite films. For PLA nanocomposite films prepared with individual nanomaterials, electrical conductivity followed the order, MWCNT>GO>CB. The electrical resistivity of PLA-nanocomposite films, that is, MWCNT-1 wt.%, GO-6 wt.%, and CB-8 wt.%, was 0.733 ± 0.02 kΩ cm, 200 ± 0.53 kΩ cm, and 276.25 ± 1.26 kΩ cm, respectively, whereas that of the 2 wt.% neat PLA film was 1760 ± 40 kΩ cm. PLA nanocomposite film (PLA-5) comprising 5 wt.% nanomaterials in a tri-mixture demonstrated the lowest electrical resistivity of 160.727 ± 3.94 Ω cm. Further, the PLA-5 nanocomposite film integrated into cotton knitted fabric, when assembled in an electrical circuit, acted as electrically conducting material. Moreover, the resistivity of the prepared assembly varied with changing pressure levels, thus proving its suitability for pressure sensing application. The value of change in resistance (R/R ₀) decreased from 11 to 3.5 on a successive increase in applied pressure from 50 to 150 kPa. Certainly, the developed flexible pressure sensing assembly based on PLA nanocomposite film and cotton knitted fabric is potentially suitable for high pressure sensing areas such as sports and posture correction.