Encapsulation is integral to electronic devices to maintain long-term functionality and stability. While a variety of materials and solutions are available for conventional silicon-based electronics, not all of them are suitable for flexible optoelectronic devices. Typically, these devices require materials with low processing temperature, while maintaining both the optical and electrical functionalities.

In this work, we show that pure polydimethylsiloxane (PDMS), PDMS–zinc oxide (ZnO) and PDMS – titanium dioxide (TiO2) nanocomposites are suitable encapsulants for flexible electronics. These coatings are electrically and thermally insulating, optically transparent, hydrophobic, and offer good environmental protection under wearable conditions. The coatings can be prepared by a simple spin coating process and annealed at temperatures less than 150 ℃. The performance of pure PDMS and PDMS-ZnO and PDMS-TiO2 were evaluated using different characterisation techniques. These coatings were tested on both printed nanowire patterns and commercial flexible RFID tags. The addition of up to 2 wt. % ZnO and TiO2 was found to improve the properties of PDMS, improving the environmental protection, without significantly affecting the optical transparency.

PDMS-ZnO nanocomposites are also investigated as protective coatings on mild steel, an
alloy highly prone to corrosion. The effect of corrosion and erosion due to abrasion by silica particles on the nanocomposites is studied and it is found that 2-4 wt. % addition of ZnO in PDMS is optimum for protecting mild steel against both corrosion and erosion.

PDMS, being an electrically non conducting elastomer, acts as a dielectric in many applications. This property is explored in its usage as an encapsulant plus dielectric for force sensors on flexible PET substrates. A water-based silver nanowire (Ag NW) ink was optimised to print the force sensor patterns using a custom-built direct writer. The response of the sensors to varying applied force was then measured as a change in capacitance.