A recent trend in the development of high mass consumption electron devices is towards electronic textiles (e-textiles), smart wearable devices, smart clothes, and flexible or printable electronics. Intrinsically soft, stretchable, flexible, Wearable Memories and Computing devices (WMCs) bring us closer to sci-fi scenarios, where future electronic systems are totally integrated in our everyday outfits and help us in achieving a higher comfort level, interacting for us with other digital devices such as smartphones and domotics, or with analog devices, such as our brain/peripheral nervous system. WMC will enable each of us to contribute to open and big data systems as individual nodes, providing real-time information about physical and environmental parameters (including air pollution monitoring, sound and light pollution, chemical or radioactive fallout alert, network availability, and so on). Furthermore, WMC could be directly connected to human brain and enable extremely fast operation and unprecedented interface complexity, directly mapping the continuous states available to biological systems. This review focuses on recent advances in nanotechnology and materials science and pays particular attention to any result and promising technology to enable intrinsically soft, stretchable, flexible WMC.

Printed electronics will bring to the consumer level great breakthroughs and unique products in the near future, shifting the usual paradigm of electronic devices and circuit boards from hard boxes and rigid sheets into flexible thin layers and bringing disposable electronics, smart tags, and so on. The most promising tool to achieve the target depends upon the availability of nanotechnology-based functional inks. A certain delay in the innovation-transfer process to the market is now being observed. Nevertheless, the most widely diffused product, settled technology, and the highest sales volumes are related to the silver nanoparticle-based ink market, representing the best example of commercial nanotechnology today. This is a compact review on synthesis routes, main properties, and practical applications.

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Left: SEM showing dendrites bridging the electrodes. Right: Retention test showing a final on/off ratio of 700 after 10 000+ s. The addition of IL to switching matrix triggers non-volatile memory and 10-fold reduction of operating voltage.

Real-time observation of the filament formation and annihilation (grey area corresponds to tungsten nanoprobe). (a) Filament formation at set threshold (orange color path corresponds to the formed filamentary path). (b) Filament dissolution at reset threshold (magenta color corresponds to the annihilation of the filamentary path). (c) Further filament formation.

The fabrication of resistive switching devices is an important technological topic nowadays because they have been pointed out as the fundamental building block for the future neuromorphic computing devices. Among the different materials developed for this purpose, polymer nanocomposites with electrical bistability are of fundamental importance due to their several advantages in terms of flexibility, low cost, and sustainability. In this work we developed a method to tune the electrical response of various polymeric matrices by modulating their physical properties. Silver nanoparticles are grown in situ in different polymeric matrices by light-induced nucleation, and the formed nanocomposites show resistive switching behavior. Here we demonstrate the fundamental role of the hosting matrix for controlling dimension and size distribution of the generated phase, achieving a nontrivial relationship between hosting matrix glass-transition temperature and set/reset voltage.

Innovative benzidine-free PANI-based inks for electrically conductive inkjet printed devices were developed and tested and the results compared with those obtained by traditional PANI. NMR investigations evidenced the presence of quinones and phenolic groups on the backbone of the innovative PANIs that are thought being responsible for the higher solubility in DMSO. A mechanism of reaction was proposed. The numerous characterizations (NMR, UV-Vis, FTIR, XPS and electrical investigations) allowed to compare protonation level, doping level, valence band maximum for both the type of PANI. The correlation among structural properties, printability, conductivity and solubility was discussed.

In the present study, silver nanocomposite resistive switching devices were fabricatedbyinkjet printing, specifically designed inks onto planar symmetrical electrodes. The printed devices show different memory/switching behaviours according to theprinted patternand number of ejected drops (in turn according to the total ejected ink volume). A drop-on-position print results in a random access type memory with a rectifying ratio of 10 3 . The effect of compliance upon switching was studied. It was observed that an increase in the compliance current changed the switching behaviour of the device to bipolar and non-volatile with an On/Off ratio of 10 4 . A print-on-the-fly method resulted in a write-once-read-manydevice instead, where oncea low resistance state was reached, the device was unable to recover its initial high resistance state. The present study gives an insight into the field-induced formation of conductive silver filaments, resulting in resistance switching. The active switching matrix ink formulation enabledeasy deposition onto various substrates, thus widening printed electronics potential. RECEIVED