No abstract

The recent interest of electronic skin (e‐skin) has pushed the research toward the development of flexible sensors, namely, for pressure detection. Several mechanisms can be used to transduce pressure into electrical signals, but piezoresistivity presents advantages due to its simplicity. The microstructuration of the films composing these sensors is a common strategy to improve their sensitivity. As an alternative to conventional and expensive photolithography techniques and low customizable techniques based on natural molds, a novel strategy for the microstructuration of polydimethylsiloxane (PDMS) films is proposed, based on molds fabricated by laser engraving. After design optimization of these microstructured films, which relies on microcones, piezoresistive sensors with a limit of detection of 15 Pa and a sensitivity of −2.5 kPa−1 in the low‐pressure regime are obtained. These sensors are used with success on the detection of the blood pressure wave at the wrist, thus exhibiting a great potential for health applications.

Smart textiles consist of discrete devices fabricated from—or incorporated onto—fibres. Despite the tremendous progress in smart textiles for lighting/display applications, a large scale approach for a smart display system with integrated multifunctional devices in traditional textile platforms has yet to be demonstrated. Here we report the realisation of a fully operational 46-inch smart textile lighting/display system consisting of RGB fibrous LEDs coupled with multifunctional fibre devices that are capable of wireless power transmission, touch sensing, photodetection, environmental/biosignal monitoring, and energy storage. The smart textile display system exhibits full freedom of form factors, including flexibility, bendability, and rollability as a vivid RGB lighting/grey-level-controlled full colour display apparatus with embedded fibre devices that are configured to provide external stimuli detection. Our systematic design and integration strategies are transformational and provide the foundation for realising highly functional smart lighting/display textiles over large area for revolutionary applications on smart homes and internet of things (IoT).

The current trend for smart, self-sustainable, and multifunctional technology demands for the development of energy harvesters based on widely available and environmentally friendly materials. In this context, ZnSnO 3 nanostructures show promising potential because of their high polarization, which can be explored in piezoelectric devices. Nevertheless, a pure phase of ZnSnO 3 is hard to achieve because of its metastability, and obtaining it in the form of nanowires is even more challenging. Although some groups have already reported the mixing of ZnSnO 3 nanostructures with polydimethylsiloxane (PDMS) to produce a nanogenerator, the resultant polymeric film is usually flat and does not take advantage of an enhanced piezoelectric contribution achieved through its microstructuration. Herein, a microstructured composite of nanowires synthesized by a seed-layer free hydrothermal route mixed with PDMS (ZnSnO 3 @PDMS) is proposed to produce nanogenerators. PFM measurements show a clear enhancement of d 33 for single ZnSnO 3 versus ZnO nanowires (23 ± 4 pm/V vs 9 ± 2 pm/V). The microstructuration introduced herein results in an enhancement of the piezoelectric effect of the ZnSnO 3 nanowires, enabling nanogenerators with an output voltage, current, and instantaneous power density of 120 V, 13 μA, and 230 μW·cm –2 , respectively. Even using an active area smaller than 1 cm 2 , the performance of this nanogenerator enables lighting up multiple LEDs and other small electronic devices, thus proving great potential for wearables and portable electronics.

The world in the 21st century is confronted with multifaceted challenges against rapid climate change and continuous ecological disturbances caused by revolutionary socio‐economic developments, accelerated expansion of disposable electronic gadgets, and growing dependence on unrecyclable raw materials, among others. The ever‐increasing consumer demand for electronic devices is significantly contributing to the world's fastest‐growing waste stream, known as electronic waste (e‐waste), which is becoming an environmental threat at an alarming rate due to its toxic legacy. The ever‐shortening lifespan of smart technologies has created a “tsunami of e‐waste,” as the United Nations has characterized it, with 50 million tons accumulated each year, of which only 20% undergo formal e‐recycling. Therefore, the challenge of optimizing the current resources management models with an aim of improving the manufacturing processes and lifecycles of electronic devices, as well as building a circular economy, has become significantly prominent. Paper/cellulose, which covers a wide range of essential needs in everyday scenarios (from packaging to writing utilities), constitutes promising candidates for the effective achievement of a circular economy. Particularly, cellulose is revealed as an advantageous material for electronic applications because of its abundant availability, which contributes to its cost‐effectiveness, straightforward fabrication process, and high recyclability and reproducibility.