International Center for Materials Nanoarchitectonics eBulletin: Quantifying Smell with Nanoparticles-functionalized Membrane-type Surface Stress Sensor and "Data-driven" Analysis

International Center for Materials Nanoarchitectonics (MANA), Japan, publishes the June 2018 issue of the MANA E-Bulletin with a featuring article on the 'MANA Independent Scientists System: Total freedom to conduct your own research', and research highlights from high impact publications on 'Quantifying smell with nanoparticles-functionalized Membrane-type Surface stress Sensor and "data-driven" analysis'; 'Pair distribution function analysis offers new insights into the structure and identity of nanomaterials; and 'Breakthrough in printed electronics enables device formation at room temperature'.

     (Photo: https://mma.prnewswire.com/media/713101/MANA_nano.jpg )

June 2018 issue of MANA eBulletin

http://www.nims.go.jp/mana/ebulletin/index.html

Feature: MANA Independent Scientists System: Total freedom to conduct your own research

http://www.nims.go.jp/mana/ebulletin/feature.html

Research Highlights

Quantifying smell with nanoparticles-functionalized Membrane-type Surface stress Sensor and "data-driven" analysis

http://www.nims.go.jp/mana/research/highlights/vol38.html

Chromatography is widely used for the quantitative identification of specific components in mixtures of compounds. For example, quantifying smell requires analysis of a complex mixture composed of thousands of chemical compounds. Although chromatography systems can be used to do so, the equipment is usually bulky and measurement procedures necessitate the time-consuming process to separate all the components into single species.

Here, Shiba, Tamura, Imamura and Yoshikawa at the International Center for Materials Nanoarchitectonics (MANA), Tsukuba, Japan, report on combining their invention, the Membrane-type Surface stress Sensor (MSS), functionalized nanoparticles, and "data-driven" analysis to quantitatively determine the concentration of alcohol from smell data contained in liquors with varying alcohol content.

Specifically, the surface of the MSS array was covered with four types of silica/titania functional nanoparticles that adsorb different target molecules in the test samples, and patterns of electrical signals were recorded.

Next, machine learning was used to analyze the massive amounts of data obtained from the electrical signal patterns to establish a prediction model for quantifying alcohol concentration of the smell sample.

Notably, materials more suitable for alcohol smells were selected based on machine learning results, and thereby the accuracy of prediction was improved.

"The importance of this research is not the fact that we determined the alcohol concentration, but that this approach enables the quantification of many other arbitrary indices," says Shiba. "These findings have paved the way for applications for quantitative evaluation of natural products, which we have demonstrated in collaboration with universities and industry."

Reference

Kota Shiba et al., "Data-driven nanomechanical sensing: specific information extraction from a complex system", Scientific Reports, 7: 3661 (2017).

DOI:10.1038/s41598-017-03875-7

Pair Distribution Function Analysis Offers New Insights into the Structure and Identity of Nanomaterials http://www.nims.go.jp/mana/research/highlights/vol39.html

Satoshi Tominaka is a scientist at International Center for Materials Nanoarchitectonics (MANA) and internationally acknowledged for research on the applications of pair distribution functions (PDF) for the analysis of nanomaterials. "The structural analysis of nanomaterials is critical for understanding their basic properties from a fundamentals scientific perspective and for applications," says Tominaka. "My approach to attain a deeper understanding of the purity and structural phases of nanomaterials is based on using PDFs. They offer powerful insights into the structural properties of nanomaterials and overcoming the limitations of X-ray diffraction analysis at the atomic scale."

Although PDF based analysis has a long history in the analysis of amorphous materials, and more recently the analysis of crystalline structures with third generation synchrotron radiations sources, PDF analysis of nanomaterials is still in its infancy.

Concisely, PDF analysis yields detailed information about the physical relationships between distances of atom pairs-for example Au-Au in Au crystals-and the density of the pairs in the crystals. This information cannot be obtained by X-ray diffractometry (XRD) that only produce broad diffraction peaks because it is not suitable for extremely small crystals.

Tominaka is working with colleagues in Japan and Europe on the development of PDF analysis for nanomaterials research on two main topics. First, the analysis of the purity of nanomaterials. "In certain materials, our PDF analysis shows large concentrations of phases of low symmetry or smaller particle sizes," says Tominaka. "The existence of mixtures of phases in nanomaterials is associated with the formation of nanomaterials under kinetically controlled conditions."

Specific reports by Tominaka on this topic include the properties of reduced titanium oxide nanoparticles ^[1] and the observation of unique electrical conduction of mesoscopic cobalt phosphide-a mesoporous semimetallic conductor-due to the coexistence of Co2P phases found by PDF analysis ^[2].

The other area of research is exploiting the power of PDF analysis for identifying unknown structures have been uncovered by using X-ray PDFs. "Certain materials are only stable as nanosized structures," says Tominaka. "Such materials cannot be identified based on data from bulk materials."

Research on materials discovery using PDF includes new insights into heterojunctions made of inert materials for electrocatalysts where gold was covered with a two-dimensional corrugated carbon−nitrogen structure ^[3]; the determination of the structure of two-dimensional boron hydride sheets which show potential for hydrogen storage ^[4]; and the discovery of disordered catalytic activity of titanate phase with TiO6 octahedral connectivity ^[5].

"My research is ongoing and still in its youth," says Tominaka. "There are still many issues to address including the development of algorisms for nanomaterials analysis."

 Reference

"Quantized Conductance Atomic Switch" K. Terabe, T. Hasegawa, T. Nakayama & M. Aono, Nature 433, 47-50 (2005), "Atomic Switch Reaching Outer Space" Research Highlights Vol. 31 (2017)

References

^[1] Tominaka et al., "Topotactic reduction of oxide nanomaterials: unique structure and electronic properties of reduced TiO2 nanoparticles", Materials Horizons, 1, 106-110, (2014).

DOI: 10.1039/C3MH00087G

^[2] Malay Pramanik et al., "Mesoporous Semimetallic Conductors: Structural and Electronic Properties of Cobalt Phosphide Systems", Angew. Chem. Int. Ed. 56, 1-6, (2017).

DOI: 10.1002/anie.201707878

^[3] Ken Sakaushi et al., "Two-Dimensional Corrugated Porous Carbon‑, Nitrogen-Framework/Metal Heterojunction for Efficient Multielectron Transfer Processes with Controlled Kinetics", ACS Nano 11, 1770−1779, (2017).

DOI:10.1021/acsnano.6b07711

^[4] Hiroaki Nishino, "Formation and Characterization of Hydrogen Boride Sheets Derived from MgB2 by Cation Exchange", J. Am. Chem. Soc. 139, 13761−1376, (2017).

DOI:10.1021/jacs.7b06153

^[5] Satoshi Tominaka et al., "Noncrystalline Titanium Oxide Catalysts for Electrochemical Oxygen Reduction Reactions", ACS Omega 2, 5209−5214, (2017).

DOI:10.1021/acsomega.7b00811

Metal Oxide/Graphene Nanosheet Composite Exhibits Unprecedented Energy Storage Properties 

http://www.nims.go.jp/mana/research/highlights/vol37.html

Printing electronic devices and circuits on flexible substrates offers the possibility of low cost, mass production of high performance organic thin film devices using technology such as "roll-to-roll".

However, conventional printing technology necessities processing at elevated temperatures of about 150°C, which damages flexible substrates causing degradation of device performance and limits the minimum feature sizes of devices.

The high temperature step is necessary to remove non-conductive ligands attached to metal nanoparticles (NP) used in the printing ink that is used for fabricating electrodes.

To resolve this issue Takeo Minari and colleagues at the World Premier International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), Tsukuba, Japan have succeeded in printing organic field effect transistor (OFET) circuits on flexible substrates at room temperature. Importantly, the devices show remarkable performance as exemplified by the high average mobility of 8 cm2 V-1 s-1 of devices, that is necessary for practical applications.

Furthermore, Xuying Liu and colleagues fabricated large‐scale, complex electronic circuits with high resolution (1 μm). The prepared organic thin‐film transistors exhibit a low contact resistance of 1.5 kΩ cm, and high mobilities of 0.3 and 1.5 cm2 V−1 s−1 in the devices with channel lengths of 1 and 5 μm, respectively.

Kanehara, Minari and colleagues developed so called π-junction gold NPs (AuNPs) that are covered with phthalocyanine conductive ligands and do not require annealing to produce electrical conduction after ink printing.

Importantly, the electrical resistivity of AuNPs is approximately 9 × 10−6 Ω cm, which is almost the same as pure Au. This approach works without annealing because the charge is transported between nanoparticles via the conductive ligands.

"The importance of these results is that electronic circuit can be formed by simply applying ink at room temperature under normal atmospheric conditions," says Minari. "This breakthrough means that circuits can be easily fabricated on the surfaces of materials that are sensitive to heat such as paper and plastics. Also, printed circuits can be produced with precision down to one micrometer, thereby making this a practical technology for real life applications."

Reference

Takeo Minari et al., "Room-Temperature Printing of Organic Thin-Film Transistors with π -Junction Gold Nanoparticles", Adv. Funct. Mater. 24, 4886-4892, (2014).

Xuying Liu et al., "Spontaneous Patterning of High-Resolution Electronics via Parallel Vacuum Ultraviolet", Adv. Mater. 28, 6568-6573, (2016).

Further information

The International Center for Materials Nanoarchitectonics, Japan
1-1 Namiki Tsukuba-shi Ibaraki, 305-0044 JAPAN
Tel:+81-029-860-4710
Email: mana-pr@ml.nims.go.jp

http://www.nims.go.jp/mana/