Suitability of plant fiber residue-based paper as substrates for sustainable thin-film thermistors

This study explores eco-friendly alternatives to flexible plastic substrates aiming to mitigate the environmental impact of electronics. Thin-film temperature sensors were fabricated on CRUSH FSC^TN-certified paper substrates made with coconut, coffee, cacao, and cherry fiber waste, substituting 15% of traditional tree cellulose. The sensors were created by sputtering a semiconducting thin-film layer of InGaZnO and zinc electrodes onto the paper substrates. The devices’ responses to relative humidity changes from 2.9 to 73% were recorded, alongside their sensing performance for temperatures \(25 \, ^\circ\) $25_{}^{\circ }$ C and \(70 \, ^\circ\) $70_{}^{\circ }$ C. The results indicate that the sensors perform optimally when subjected to sudden and significant temperature changes and portray sensitivities values of \(-\) $-$ 1.83 \(\%~ \, ^\circ \textrm{C}^{\text{-}}\) $\%_{}^{\circ }{\text{C}}^{\text{-}}$ \(^1\) $_{}^1$ (heating) and \(-\) $-$ 1.38 \(\%\) $\%$   \(\, ^\circ\) $_{}^{\circ }$ \(\hbox {C}^{\text{-}}\) ${\text{C}}^{\text{-}}$ \(^1\) $_{}^1$ (cooling). Additionally, the dissolution of the transient sensors in water was examined to assess their sustainability.