Optically transparent and high dielectric constant reduced graphene oxide (RGO)-PDMS based flexible composite for wearable and flexible sensors

摘要

Optically transparent flexible materials possessing high dielectric constant have tremendous applications in wide range applications such as flexible electronics devices, micro-electro-mechanical systems(MEMS),wearable sensors and biomedical devices. Out of all the polymers, PDMS(Polydimethylsiloxane) is very well known for its excellent properties and being utilized for biomedical devices and microfluidic applications. However, due to the poor electrical properties both electrical conductivity and dielectric constant, this material is not utilized as a sensing material for fabrication of wearable sensors or electronic devices. Though, some progress has been achieved to improve the conductivity of this material, for this purpose higher vol.% filler material is employed, that generate cracks and defects. Therefore, utilizing this material for the resistive based sensor fabrication is not that promising and also several applications such as touch screens, wearable electronics, touch sensors for keyboards, flexible switches and human-machine interfacing applications require capacitive-based sensors. In this work, we have developed a transparent flexible composite dielectric material by employing a very low vol.% chemically treated RGO as a filler in the PDMS matrix. The impacts of the uniform distribution of the RGO in the PDMS based composite's flexibility, optical transparency and dielectric constant are investigated. The uniform distribution of the RGO in the PDMS matrix is obtained by the chemical treatment process prior to the fabrication of the composite, that helps to improve the flexibility of the composite material by improving the cross-linking bond between the RGO and PDMS matrix. Moreover, by controlling the uniform distribution of the RGO, it is possible to obtain 82% transparency with high dielectric constant(38) flexible composite material. We believe that this optical transparent and flexible composite can possibly be utilized for capacitive based weara