A multistate nonvolatile memory operated at sublithographic scale has been strongly desired since other nonvolatile memories have confronted the fundamental size limits owing to their working principles. Resistive switching (RS) in metal-oxide-metal junctions, so-called ReRAM, is promising for next generation high-density nonvolatile memory. Self-assembled oxide nanowire-based RS offers an attractive solution not only to reduce the device size beyond the limitation of current lithographic length scales but also to extract the underlying nanoscale RS mechanisms. Here we demonstrate the multistate bipolar RS of a single Co(3)O(4) nanowire (10 nm scale) with the endurance up to 10(8). In addition, we succeeded to extract a voltage-induced nanoscale RS mechanism rather than current-induced RS. These findings would open up opportunities to explore not only for the intrinsic nanoscale RS mechanisms with the ultimate size limit but also for next generation multistate three-dimensional ReRAM.

We demonstrate the first reported methodology using nanowires that unveils massive numbers of cancer-related urinary microRNAs.

A stress relaxation effect on the transport properties of strained vanadium dioxide epitaxial thin films grown on TiO 2 ͑001͒ single crystal was investigated. When varying the film thickness ranging from 10 to 30 nm, there were no significant changes on the crystal structures identified by x-ray diffraction, i.e., no observable stress relaxation effects. On the other hand, increasing the film thickness resulted in the drastic changes on the transport properties including emerging the multisteps of the metal-insulator transition and also increasing the resistivity. The discrepancy between the observed crystal structure and the transport properties was related to the presence of the nanoscale line cracks due to thermal stress. Thus controlling thermal stress relaxation rather than the stress due to the lattice mismatch is critical to investigate the intrinsic nature on the transport properties of strained vanadium dioxide epitaxial thin films.

We have demonstrated the nonvolatile bipolar resistive memory switching in single crystalline NiO heterostructured nanowires for the first time. The self-assembled NiO nanowires are expected to open up opportunities to explore not only the detailed nanoscale mechanisms in NiO resistive memory switching but also next-generation nanoscale nonvolatile memory devices with the potential for high-density device integration and improved memory characteristics.

We have demonstrated the construction of highly stable resistive switching (RS) junctions with a metal/NiO nanowire/metal structure and used them to elucidate the crucial role of redox events in the nanoscale bipolar RS. The presented approaches utilizing oxide nanowire/metal junctions offer an important system and platform for investigating nanoscale RS mechanisms of various oxide materials.

On the development of flexible electronics, a highly flexible nonvolatile memory, which is an important circuit component for the portability, is necessary. However, the flexibility of existing nonvolatile memory has been limited, e.g. the smallest radius into which can be bent has been millimeters range, due to the difficulty in maintaining memory properties while bending. Here we propose the ultra flexible resistive nonvolatile memory using Ag-decorated cellulose nanofiber paper (CNP). The Ag-decorated CNP devices showed the stable nonvolatile memory effects with 6 orders of ON/OFF resistance ratio and the small standard deviation of switching voltage distribution. The memory performance of CNP devices can be maintained without any degradation when being bent down to the radius of 350 μm, which is the smallest value compared to those of existing any flexible nonvolatile memories. Thus the present device using abundant and mechanically flexible CNP offers a highly flexible nonvolatile memory for portable flexible electronics.

Conventional concepts of resistive pulse analysis is to discriminate particles in liquid by the difference in their size through comparing the amount of ionic current blockage. In sharp contrast, we herein report a proof-of-concept demonstration of the shape sensing capability of solid-state pore sensors by leveraging the synergy between nanopore technology and machine learning. We found ionic current spikes of similar patterns for two bacteria reflecting the closely resembled morphology and size in an ultra-low thickness-to-diameter aspect-ratio pore. We examined the feasibility of a machine learning strategy to pattern-analyse the sub-nanoampere corrugations in each ionic current waveform and identify characteristic electrical signatures signifying nanoscopic differences in the microbial shape, thereby demonstrating discrimination of single-bacterial cells with accuracy up to 90%. This data-analytics-driven microporescopy capability opens new applications of resistive pulse analyses for screening viruses and bacteria by their unique morphologies at a single-particle level.

Resistive switching (RS) memory effect in metal-oxide-metal junctions is a fascinating phenomenon toward next-generation universal nonvolatile memories. However the lack of understanding the electrical nature of RS has held back the applications. Here we demonstrate the electrical nature of bipolar RS in cobalt oxides, such as the conduction mechanism and the switching location, by utilizing a planar single oxide nanowire device. Experiments utilizing field effect devices and multiprobe measurements have shown that the nanoscale RS in cobalt oxides originates from redox events near the cathode with p-type conduction paths, which is in contrast with the prevailing oxygen vacancy based model.