The fabrication and characterization of green, flexible, and ultra‐thin supercapacitors that are able to operate above 1.5 V is reported, using an all‐printed fabrication process. The devices are produced by aqueous spray casting of a natural‐derived electrolyte ionogel composed by 2‐hydroxyethyl cellulose and by the ionic liquid choline lactate, while the electrodes are composed of highly porous nanostructured carbon films deposited by supersonic cluster beam deposition (SCBD). The obtained supercapacitors (device thickness < 10 μm) are stable to bending and they possess power values up to 120 kW kg^–1. The combination of aqueous spray casting and SCBD constitutes a versatile, scalable, and eco‐friendly fabrication process able to directly print interconnected elements suitable for transient electronic systems.

The interest for biodegradable electronic devices is rapidly increasing for application in the field of wearable electronics, precision agriculture, biomedicine, and environmental monitoring. Energy storage devices integrated on polymeric substrates are of particular interest to enable the large-scale on field use of complex devices. This work presents a novel class of eco-friendly supercapacitors based on biodegradable poly(3-hydroxybutyrrate) PHB, ionic liquids, and cluster-assembled gold electrodes. By electrochemical characterization, we demonstrate the possibility of tuning the supercapacitor energetic performance according to the type and amount of the ionic liquid employed. Our devices based on hydrophobic plastic materials are stable under cyclic operation and resistant to moisture exposure.

We report the synthesis, fabrication and characterization of a hybrid hydrogel/cellulose nanocomposite, which exhibits high-performance electro–mechanical underwater actuation and high sensitivity in response to electrical stimuli below the standard potential of water electrolysis. The macromolecular structure of the material is constituted by an electroactive hydrogel, obtained through a photo-polymerization reaction with the use of three vinylic co-monomers: Na-4-vinylbenzenesulfonate, 2-hydroxyethylmethacrylate, and acrylonitrile. Different amounts (from 0.1% to 1.4% w/w) of biodegradable cellulose nanocrystals (CNCs) with sulfonate surface groups, obtained through the acidic hydrolysis of sulphite pulp lapsheets, are physically incorporated into the gel matrix during the synthesis step. Freestanding thin films of the nanocomposites are molded, and their swelling, mechanical and responsive properties are fully characterized. We observed that the embedding of the CNCs enhanced both the material Young’s modulus and its sensitivity to the applied electric field in the sub-volt regime (down to 5 mV cm ⁻¹ ). A demonstrator integrating multiple actuators that cooperatively bend together, mimicking the motion of an electro-valve, is also prototyped and tested. The presented nanocomposite is suitable for the development of soft smart components for bio-robotic applications and cells-based and bio-hybrid fluidic devices fabrication.