Characterization of modified TEMPO-oxidized cellulose nanofibers as a substrate for applications in printed, transient electronics

The rise of IoT and 5 G-enabled microwave communications demands sustainable substrates for flexible and printed electronic devices. We present a fully bio-based and biodegradable substrate for transient microwave electronics with controllable sensing functionality. The substrate is composed of TEMPO-oxidized cellulose nanofibrils (TCNF) reinforced with poly (vinyl alcohol) (PVA) and alkyl ketene dimer (AKD), which together enhance mechanical robustness, printability, and moisture resistance. Incorporation of PVA significantly improved ductility and toughness, enabling substrates with much higher strain tolerance and mechanical reliability during device operation under harsh conditions. Further surface modification with AKD increased hydrophobicity, achieving a water contact angle of 102 5 , which is critical for maintaining structural stability under humid conditions and also increasing dimensional accuracy of the printing. The wettability of silver nanoparticles (AgNPs) and print resolution were well demonstrated with bending and sheet resistances of printed lines similar to poly (ethylene terephthalate) substrates. A printed coplanar waveguide (CPW)-fed antenna is fabricated on the optimized substrate as a microwave device demonstrator, and its performance is confirmed. Hence, the substrate introduced in this study is a suitable candidate for printed transient microwave electronics with controllable sensing capabilities, which can be a sustainable alternative to the conventional petroleum-based polymer ones. • The Tempo-oxidized nanocellulose/poly(vinyl alcohol) composite substrate exhibits enhanced mechanical properties.. • Moisture uptake in the composite cellulose substrate is regulated by poly(vinyl alcohol) and alkyl ketene dimer.. • The composite cellulose substrate coated with alkyl ketene dimer exhibits instantaneous wetting when printed with silver nanoparticle ink.. • The printed coplanar waveguide antenna on the bio-based substrate demonstrates excellent microwave performance..