Aerosol Jet Printed Organic Memristive Microdevices Based on a Chitosan:PANI Composite Conductive Channel

In this study we show a chitosan:polyaniline (CPA)-based ink, responding to eco-biofriendly criteria, specifically developed for the manufacturing of the first organic memristive device (OMD) with an aerosol jet printed conductive channel. Our contribution is in the context of bioelectronics, where there is an increasing interest in emulating neuro-morphic functions. In this framework, memristive devices and systems have been shown to be well suited. In particular organic-based devices are envisaged as very promising in some applications, such as brain-machine interfacing, owing to specific properties of organics (e.g., biocompatibility, mixed ionic-electronic conduction). On the other hand, the research activities on flexible organic (bio)electronic devices and direct writing (DW) noncontact techniques increasingly overlap in the effort of achieving reliable applications benefiting from the rapid prototyping to accomplish a fast device optimization. In this context, ink-based techniques, such as aerosol jet printing (AJP), although particularly well suited to implement 3D-printed electronics due to advantages it offers in terms of a wide set of allowed printable materials, still require research efforts aimed at conferring printability to the desired precursors. The developed CPA composite was characterized by FTIR, DLS, and MALDI-TOF techniques, while the related aerosol jet printed films were studied by SEM and profilometry. Taking advantage of the intrinsic and stable electrical conductivity of CPA films, which do not necessarily require any acidic treatment to promote a sustained charge carrier conduction, 10 mu m short-channel OMDs were hence manufactured by interfacing the printed CPA layers with a solid polyelectrolyte (SPE). We accordingly demonstrated prototypes of stable and best performing OMD devices with downscaled features, showing well-defined counterclockwise hysteresis/rectification and an enhanced durability. These properties pave the way to further improving performance, as well as to realizing a direct integration of the devices into hardware neural networks by in-line fabrication routes

Effects of noise sourcing on organic memristive devices

The effects of noise on any electronic system is a crucial aspect for the delineation of the proper functioning of circuits. Different and consolidated models have been proposed for classical electronic circuital elements but the effect of noise sourcing on memristive devices still lacks a wide and rich experimental description. Despite the larger use of Gaussian white noise in the stimulation of memristive systems, the use of uniform white noise has been recently proposed as a possible method for underlining variations in the impedance of an electronic device and in dynamic monitoring the system evolution. By applying uniform white noise to organic memristive devices (OMDs) while measuring the resulting current noise, we dynamically monitored the effects of noise amplitude on memristive properties. In fact OMDs functioning is based on the interfacial redox activity between polyaniline and a liquid electrolyte and constitutes an intrinsically impedance variation of the channel. We show that noise sourcing affects the hysteresis loops, the typical characteristics of electronic systems endowed with memory