Network-based Molecular Electronics: Neuromorphic Materials, Properties and Nanoscale Charge Detection Methods
Takuya Matsumoto
Department of Chemistry, Graduate School of Science, Osaka University
In recent decades, studies on the electronic properties and functions of single molecules have made significant advances and single molecular transistors have been demonstrated. Such investigations, however have not directly led to actual molecular-scale electronic devices, due to the lack of effective technologies for wiring between molecules. Beyond single molecular transistors, the exploration of device architecture is a central issue in molecular-scale electronics. One of the attractive directions is the realization of neural networks that utilize self-assembled molecular systems. The simplest neuron communication model is represented by a step function that corresponds to neuron firing. In this talk, I would like to introduce recent achievements for nonlinear current-voltage characteristics, neural functions and electrostatic force microscopy for charge tracking in molecular systems.
Takuya Matsumoto obtained his Ph.D. in physical chemistry with the electron paramagnetic resonance of supersonic oxygen beam from Osaka University in 1990. He became Research Associate (1990) and Associate Professor (1998) at Institute of Scientific and Industrial Research, Osaka University. He was appointed Professor of Chemistry, Graduate school of Science, Osaka University in 2012. His main field of research is the study of biological and organic molecules at surfaces using scanning probe microscopy. Recent interests focus on molecular electronics.
Neuron-like signal generation from random network of single-walled carbon nanotube and nanoparticle complex
Hirofumi Tanaka
Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology
For the future development of molecular electronics, nanoscale molecular devices should be constructed using nanometer-sized electrical wiring. Here, single-walled nanotube (SWNT) has been mixed with nanoparticles of 1:12 phosphomolybdic acid (PMo12). PMo12 also has interesting electric properties like the obtained I-V curve always showed peaks which are called negative differential resistance (NDR). Because NDR is one of the components of noise generator, a network of SWNT/PMo12 was fabricated to be expected as noise generator and bias was applied. Amplitude of current, noise strength, was increased as bias increased from 0V to 125V. Further, current became unstable when 150 V was applied to the same device and then generated pulse current. The pulses are obtained as special case of the instability. The phenomena are expected to be utilized as neuron devices used in brain computing.
Prof. Tanaka completed his doctorate in materials science at Osaka University in 1999. In 2012, he earned best paper award of Japanese Society of Applied Physics. After working in RIKEN and the Pennsylvania State University as a postdoc researcher and Institute of Molecular Science and Osaka University as an assistant professor, he moved to department of Human Intelligence Systems, Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology as a full professor in April 2014 and is focusing on neuromorphic electric nanodevices.
Creative Use of Noise Brings Bio-Inspired Electronic Improvement
Megumi Akai-Kasaya
Department of Precision Science & Technology, Graduate School of Engineering, Osaka University
The noise-enhanced signal transmission and detection system, which is probabilistic but consumes low power, has not been used in modern electronics. We explored the ability of molecules to affect the noise generated by carbon nanotube-based nanoscale electronic devices. It was found that molecule gave unique noise signals related to the properties of the molecules in room temperature. Improved knowledge of the molecular-level origin of noise led a way to control in terms of magnitude and frequency characteristic of noise in electronic device. We demonstrated that a summing network stochastic resonance device consisting of molecular functionalized SWNTs detected small subthreshold signal. Use of noise and fluctuation of nano-materials will realize a device that could potentially usher in a new era in bio-inspired sensors and new approaches to computing.
Megumi Akai-Kasaya obtained her Ph. D. in physical chemistry from Osaka University in 1997 on the topic of STM imaging of single pentacene molecule on a surface. She is currently an Assistant Professor of the Division of Precision Science & Technology at Graduate School of Engineering Osaka University. During 2005–2009 and 2015-pres. she joined the PRESTO program of ‘‘Structure Control and Function'' and " Nanoelectronics" at Japan Science and Technology Agency. Her scientific interests is a realization of physical neuromorphic device consisting of nanomaterials.
Nonlinear electrical property of Ruthenium complex in nanoscale
Yoichi Otsuka, Satoshi Nishijima, Takumi Muramatsu, Hiroaki Ozawa, Masa-Aki Haga, Takuya Matsumoto
Department of chemistry, graduate school of science, Osaka University
For the realization of information processing with molecules, nonlinear electrical properties with threshold voltage is important. We have been studied the nonlinear electrical properties of Ruthenium complex (Ru- comp) with nanoscale electrical measurement technique such as nanoparticle bridge junction and conductive probe atomic force microscope. For the expression of clear threshold voltage, we found the isolation of Ru- comp from the electrode by inserting the self-assembled monolayer between them is important. We also found the dinuclear Ru-comp shows the asymmetric current-voltage characteristics with electronic hysterisis loop. Our results indicate the possibility of the use of complex for the molecular electronics.
Yoichi Otsuka obtained his Ph.D. in chemistry from Osaka University in 2006 on the topics of nanoscale electrical measurements of DNA molecules. He is currently an assistant professor of division of chemistry at graduate school of science, Osaka university. From 2003-2006, he was the research fellowship for Young Scientists, Japan Society for the Promotion of Science. He was the research scientist in the division of analysis and biomedical imaging, Canon Inc., from 2006-2015. His scientific interest include nanoscale electrical properties toward information processing with molecular network and the dynamic behavior of molecules inside nano-volume liquid.
