Developing sustainable options for energy storage in textiles is needed to power future wearable "Internet of Things" (IoT) electronics. This process must consider disruptive alternatives that address questions of sustainability, reuse, repair, or even a second life application. Herein, we pair stretch-broken carbon fiber yarns (SBCFYs), as current collectors, and an in situ regenerated cellulose-based ionic hydrogel (RCIH), as an electrolyte, to fabricate 1D fiber-shaped supercapacitors (FSCs). The areal specific capacitance reaches 433.02 μF·cm^-2 at 5 μA·cm^-2, while the specific energy density is 1.73 × 10^-2 μWh·cm^-2. The maximum achieved specific power density is 5.33 × 10^-1 mW·cm^-2 at 1 mA·cm^-2. The 1D FSCs possess a long-life cycle and 92% capacitance retention after 10 000 consecutive voltammetry cycles, higher than similar ones using the reference PVA/H₃PO₄ gel electrolyte. Additionally, the feasibility and reproducibility of the produced devices were demonstrated by connecting three devices in series and parallel, showing a small variation of the current density in flat and bent positions. An environmentally responsible approach was implemented by recovering the active materials from the 1D FSCs and reusing or recycling them without compromising the electrochemical performance, thus ensuring a circular economy path.

Fully printed and flexible inorganic electrolyte gated transistors (EGTs) on paper with a channel layer based on an interconnected zinc oxide (ZnO) nanoparticle matrix are reported in this work. The required rheological properties and good layer formation after printing are obtained using an eco-friendly binder such as ethyl cellulose (EC) to disperse the ZnO nanoparticles. Fully printed devices on glass substrates using a composite solid polymer electrolyte as gate dielectric exhibit saturation mobility above 5 cm² V⁻¹ s⁻¹ after annealing at 350 °C. Proper optimization of the nanoparticle content in the ink allows for the formation of a ZnO channel layer at a maximum annealing temperature of 150 °C, compatible with paper substrates. These devices show low operation voltages, with a subthreshold slope of 0.21 V dec⁻¹, a turn on voltage of 1.90 V, a saturation mobility of 0.07 cm² V⁻¹ s⁻¹ and an I_on/I_off ratio of more than three orders of magnitude.

Low-cost and large-scale production techniques for flexible electronics have evolved greatly in recent years, having great impact in applications such as wearable technology and the internet of things. In this work, we demonstrate fully screen-printed UV photodetectors, successfully fabricated at a low temperature on a cork substrate, using as the active layer a mixture of zinc oxide nanoparticles and ethylcellulose. The photoresponse under irradiation with a UV lamp with peak emission at 302 nm exhibited a quasi-quadratic behavior directly proportional to the applied voltage, with a photocurrent of about 5.5 and 20 μA when applying 1.5 V and 5 V, respectively. The dark current stayed below 150 nA, while the rise and falling times were, respectively, below 5 and 2 s for both applied voltages. The performance was stable over continuous operation and showed a degradation of only 9% after 100 bending cycles in a 45 mm radius test cylinder. These are promising results regarding the use of this type of sensor in wearable applications such as cork hats, bracelets, or bags.

The present work reports on the handwriting of electronic circuits on paper based on the deposition of an inorganic oxide semiconductor, exploiting the pen‐on‐paper (PoP) approach. The method relies on the use of a parallel metal plate pen, well known from calligraphy applications, which permits controlled deposition of a continuous zinc oxide (ZnO) dual‐phase layer on conventional printing paper. The hand‐drawn ZnO film exhibits a continuous and uniform surface with a thickness of roughly 1.5 µm, allowing the application as active layer for UV sensors and field effect transistors on paper. Photocurrent generated from the UV radiation reaches values up to 3.4 mA cm⁻² with switching times on the order of few seconds. The final written paper transistors, where paper plays simultaneously the role of substrate and dielectric, reaches On/Off current ratios (I_On/I_Off) of about two orders of magnitude and field effect mobility close to 5 × 10⁻³ cm² V⁻¹ s⁻¹. As a final proof‐of‐concept a common source amplifier showing clear inverting characteristics is fabricated using a PoP written driving ZnO‐based transistor and a pencil‐drawn track as the load resistance.

Despite the undoubtable interest in energy conversion, thermoelectric (TE) materials can be approached from a temperature-sensitive perspective, as they can detect small thermal stimuli, such as a human touch or contact with cold/hot objects. This feature offers possibilities for different applications one of them being the integration with scalable and cost-effective, biocompatible, flexible, and lightweight thermal sensing solutions, exploring the combination of sustainable Seebeck coefficient-holding materials with printing techniques and flexible substrates. In this work, ethyl cellulose and graphite flakes inks were optimized to be used as functional material for flexible thermal touch sensors produced by screen-printing. Graphite concentrations of 10, 20 and 30 wt% were tested, with 1, 2 and 3 printed layers on four different substrates—office paper, sticker label paper, standard cotton, and organic cotton. The conjugation of these variables was assessed in terms of printability, sheet resistance and TE response. The best electrical-TE output combination is achieved by printing two layers of the ink with 20 wt% of graphite on an office paper substrate. Subsequently, thermal touch sensors with up to 48 TE elements were produced to increase the output voltage response (>4.5 mV) promoted by a gloved finger touch. Fast and repeatable touch recognition were obtained in optimized devices with a signal-to-noise ratio up to 340 and rise times bellow 0.5 s. The results evidence that the screen-printed graphite-based inks are highly suitable for flexible TE sensing applications.