Casein-derived functional layers for electronic memory, sensing and energy storage applications: A comprehensive review

This review provides a comprehensive overview of a casein-derived functional layer developed for next-generation electronic memory, sensing, and green energy applications. Moving beyond its traditional use as a passive structural matrix, this study evaluates the performance of a distinct biopolymer system, including Milk, Casein, Sodium Caseinate (NaCas), casein/polyvinyl alcohol (Casein/PVA), casein/polyacrylamide/carbon nanotube (CA/MWCNT/PAAm) hybrid networks. The added value of these casein-based function layers are established through the quantified performance milestones, highlight the potential of these sustainable materials: bio-memristors display non-volatile memory data retention exceeding 10 5 seconds with cyclic endurance over 6000 cycles, electric double-layer (EDL) synaptic transistors yield specific capacitances up to 3.58 μF cm −2 operating under low-power regimes (< 1 V), and flexible double-network hydrogel strain sensors achieve gauge factors up to 12.46 with an extreme elongation at break of 2288%. To address the operational limitations such as moisture sensitivity and precursor instability, we evaluate thin-film encapsulation capping strategies (e.g., Ta 2 O 5 or Al 2 O 3 barriers) to suppress environmental degradation, alongside standardized microwave-assisted irradiation and enzymatic normalization to resolve precursor structural variance.