Toward Fully Printed Memristive Elements: a-TiO2 Electronic Synapse from Functionalized Nanoparticle Ink

Electronic devices that emulate biofunctionalities, such as synaptic plasticity, present a promising route to versatile and energy-efficient neuromorphic computing systems. As the demand for rapid prototyping and environmentally friendly fabrication of such devices rises, there are significant incentives toward finding solutions for low-cost materials and flexible deposition techniques. The development of printed electronic devices is still at an infant stage, presenting a timely opportunity to investigate material robustness and routes to overcoming fabrication obstacles toward fully printed electronic synapses. In this work, a low-power, fully printed Ag (200 nm)/a-TiO2 (80 nm)/Ag (160 nm) memristive device is demonstrated. The first electrical characterization of early devices exhibits biomimetic properties with an indication of activity-dependent plasticity. The active material is derived from a simplified nanoparticle ink formulation developed in-house. The ink characterization confirms that the formulation fulfills the criteria for efficient jetting while exhibiting a dwell time of 4 months. Additionally, the common detrimental fabrication issues of layer cracks and control over uniformity here are both overcome. The ink optimization and the investigation of the electrical framework under which the memristive element responds synaptically present a favorable approach to alternative fabrication methods for future neuromorphic electronics.