Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japanese Society of Tribologists  

<p>Reducing the viscosity of the lubricant is an effective way to improve the energy efficiency of automobiles. However, designing a lubricant with the desired properties requires elucidating the relationship between viscosity and molecular structure. In this study, we measured the temperature dependence of the dielectric relaxation of model lubricants with different molecular structures. Dielectric relaxation measurements were used to evaluate the influence of ambient viscosity on the motility of single molecules. In addition, we measured the temperature dependence of the lubricant viscosity using a rotational viscometer. By comparing the flow viscosity and dielectric relaxation measurement results, we showed that the activation volume and energy of the luburicant, which determine viscosity, can be resolved. As a result, we succeeded in quantitatively evaluating the contribution of molecular structure to changes in the activation energy, and elucidated the effect of the density of polar groups per molecule on changes in the activation volume.</p>

DOI： 10.2474/trol.18.91

Web of Science

Scopus

CiNii Research

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Macromolecules  

The conformations and lubricating film formation ability of adsorbed films on metal surfaces formed by poly(alkyl methacrylate) (PAMA) homopolymers with different polarities from nonpolar lubricant oil were investigated. It was found that as the polarity of the polymers became higher, the chains in the adsorbed films adsorbed more loosely to the surfaces (i.e., they formed more loops and tails). The loosely adsorbed chains temporarily trapped free polymer chains flowing into the gap between sliding surfaces, resulting in a much thicker lubricating film. Thus, the sliding surfaces were better protected from wear caused by direct contact. On the other hand, flattened chains occupying in the adsorbed film formed by low polarity-polymers could not trap free polymer chains, resulting in a thinner lubricating film.

DOI： 10.1021/acs.macromol.2c02238

Web of Science

Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

Abstract

High-performance organic friction modifiers (OFMs) added to lubricating oils are crucial for reducing energy loss and carbon footprint. To establish a new class of OFMs, we measured the friction and wear properties of N-(2,2,6,6-tetramethyl-1-oxyl-4-piperidinyl)dodecaneamide referred to as C₁₂Amide-TEMPO. The effect of its head group chemistry, which is characterized by a rigid six-membered ring sandwiched by an amide group and a terminal free oxygen radical, was also investigated with both experiments and quantum mechanical (QM) calculations. The measurement results show that C₁₂Amide-TEMPO outperforms the conventional OFMs of glyceryl monooleate (GMO) and stearic acid, particularly for load-carrying capacity, wear reduction, and stability of friction over time. The friction and wear reduction effect of C₁₂Amide-TEMPO is also greatly superior to those of C₁₂Ester-TEMPO and C₁₂Amino-TEMPO, in which ester and amino groups replace the amide group, highlighting the critical role of the amide group. The QM calculation results suggest that, in contrast to C₁₂Ester-TEMPO, C₁₂Amino-TEMPO, and the conventional OFMs of GMO and stearic acid, C₁₂Amide-TEMPO can form effective boundary films on iron oxide surfaces with a unique double-layer structure: a strong surface adsorption layer owing to the chemical interactions of the amide oxygen and free radical with iron oxide surfaces, and an upper layer owing to the interlayer hydrogen-bonding between the amide hydrogen and free radical or between the amide hydrogen and oxygen. Moreover, the intralayer hydrogen-bonding in each of the two layers is also possible. We suggest that in addition to strong surface adsorption, the interlayer and intralayer hydrogen-bonding also increases the strength of the boundary films by enhancing the cohesion strength, thereby resulting in the high tribological performance of C₁₂Amide-TEMPO. The findings in this study are expected to provide new hints for the optimal molecular design of OFMs.

DOI： 10.1007/s40544-022-0610-0

Web of Science

Scopus

Other Link： https://link.springer.com/article/10.1007/s40544-022-0610-0/fulltext.html

Language：English   Publishing type：Research paper (scientific journal)  

High-performance organic friction modifiers (OFMs) added to lubricating oils are crucial for reducing friction and wear under boundary lubrication. To guide the development of higher-performance OFMs, the boundary lubrication characteristics and working mechanisms of existing OFMs should be elucidated. In this study, the nanoscale frictional properties of conventional and recently developed TEMPO-based OFMs were measured using lateral force microscopy and interpreted using the Eyring activation energy model. We found that the parameters in this model provided insights into the characteristics of OFMs during loaded sliding, including the load-carrying capacity, adsorption speed, and shear-motion location. Therefore, analysis using the Eyring activation energy model effectively complements the LFM measurements and provides a new perspective for evaluating the boundary lubrication characteristics of OFMs beneficial for the development of high-performance OFMs.

DOI： 10.1016/j.triboint.2022.108052

Web of Science

Scopus

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

<p>Using molecular dynamics with our developed reactive force field, we investigated the effect of water on the mechanochemical reaction of nanometer-thick perfluoropolyether D-4OH films at the head–disk interface of heat-assisted magnetic recording. Three types of reactions were observed: hydrolysis, end group–end group association (EEA) reaction, and end group–main chain association (EMA) reaction. The simulation results showed that water molecules accelerate the decomposition of D-4OH and such effect is more noticeable at low pressures than at high pressures. The presence of water induces hydrolysis and accelerates the EEA reaction, whereas the EMA reaction is greatly accelerated by pressure rather than water.</p>

DOI： 10.1299/jsmeiip.2023.iipa-1-10

CiNii Research

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

<p>Reducing lubricant viscosity is one effective way to improve the energy efficiency of automobiles. Designing a lubricant with the desired properties requires elucidating the relation between viscosity and molecule structure. In this study, we measured the temperature dependence of dielectric relaxation for lubricants with different molecular structures. The dielectric relaxation measurements can evaluate the motility of single molecules influenced by the ambient viscosity. Additionally, we measured the temperature dependence of lubricant viscosity with a rotational viscometer. By comparing the results of both flow viscosity and dielectric relaxation measurements, we find a correlation between flow activation energy and single-molecule mobility when viscosity is dependent on molecular weight, while there is no correlation between them when polarity dominantly affects viscosity.</p>

DOI： 10.1299/jsmeiip.2023.iipa-6-16

CiNii Research

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

<p>With the development of microfabrication and surface treatment technologies, the gaps between elements in mechanical and electronic components have narrowed from the micrometer to the nanometer-sized. Fluid slippage at the solid/liquid interface is one of the phenomena that are considered to occur in micro/nanometer-sized gaps, and frictional properties there are expected to be different from those in macro gaps. For proper lubrication design in nanometer-sized gap, it is necessary to quantify the slippage at the interface. In this study, we used the fluorescence tracking of quantum dots with diameters of a few nanometers to measure the squeezed flow in nanometer-sized gap. Quantitative lateral velocity distributions were measured, and we estimated the slippage based on our proposed analysis of the number distribution of measured velocity values that depends on the flow profile in the depth direction. Our obtained results suggested that interfacial slippage occurred in the gap about less than 200 nm.</p>

DOI： 10.1299/jsmeiip.2023.iipa-6-5

CiNii Research

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

<p>Polymer additives in lubrication oils are known to play a role as viscosity index improvers that change the temperature dependence of viscosity. On the other hand, it is assumed that polymers adsorbed on surfaces contribute to low friction, and clarification of their mechanical properties and temperature dependence is essential for lubrication design. In our previous research, we have successfully measured the gap dependence of mechanical properties (shear viscoelasticity) of base oils by applying the fiber wobbling method (FWM), a nano-rheological measurement method that we originally developed. In this study, we developed a temperature-control stage for FWM to measure the temperature dependence of shear viscoelasticity in nano-gaps of polymer-added lubricants.</p>

DOI： 10.1299/jsmeiip.2023.iipa-6-11

CiNii Research

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

<p>To elucidate the cause of increase in shear resistance in alignment process for nano imprint lithography (NIL), by using vertical-objective-type ellipsometric microscopy (VEM) combined with a micro-cylinder structure and gap feedback-control, shear response of nano-confined liquid film mimicking a NIL resist film were measured. The three kinds of samples were prepared; monomer, monomer with release agent, and monomer with polymerization initiator. The increase in the shear resistance force was not detected with the monomer alone, but with the addition of additives. The shear response waveforms indicated that the resist solidifies at nanometer gaps and may melt above the yield shear force. These results suggest that the additive is unevenly distributed near the sliding solid surfaces and changes the physical properties of the monomer near the solid surfaces, resulting in a significant increase in shear resistance force at the nano gaps. This mechanism is thought to be responsible for the increased shear resistance force in the NIL alignment process as well.</p>

DOI： 10.1299/jsmeiip.2023.iipa-6-15

CiNii Research

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.triboint.2021.107341

Web of Science

Scopus

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

<p>With the development of microfabrication and surface processing technologies, gap between two solid surfaces in Micro electro mechanical systems (MEMS) and Micro total analysis system (μTAS) becomes microgap to nanogap. For designing the devices and verifying the principle of MEMS and μTAS, experimental method to measure flow distribution of fluid confined in nanogap is required. In this study, we aim to realize the measurement of the flow distribution of squeezed flow in the nanogap using fluorescence images of nanoparticles. We evaluated the validity of our experimental method by comparing our experimental results with the theoretical results and clarified the size of nanogap that can be measured using our method.</p>

DOI： 10.1299/jsmeiip.2022.iip2r3-h12

CiNii Research

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

<p>Using molecular dynamics with our developed reactive force field, we investigated the effect of water and/or oxygen on the mechanochemical reaction of nanometer-thick perfluoropolyether D-4OH films at the head–disk interface of heat-assisted magnetic recording. The simulation results showed that the presence of oxygen, water, or both accelerated the mechanochemical reaction of D-4OH. For oxygen only, no decomposition reaction occurred, and oxidation reactions were observed in which an oxygen molecule was inserted between the C–C bond in the end group of D-4OH. In contrast, in the presence of water, hydrolysis decomposition reactions at the C–O bond in the end group of D-4OH occurred frequently, and polymerization reactions were also observed.</p>

DOI： 10.1299/jsmeiip.2022.iip2r1-a06

CiNii Research

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

<p>Thickness control of thin liquid films is useful in various fields for the control of physical properties of solid surfaces such as wettability and multilayer fabrication using light-curing resin liquid films. In this report, we propose a precise thickness control method with nanometer-order resolution using intermolecular interaction between solid and liquid, and report its experimental verification.</p>

DOI： 10.1299/jsmeiip.2022.iip2r3-h05

CiNii Research

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

DOI： 10.1299/jsmeiip.2022.iip2r3-h11

CiNii Research

Language：Japanese   Publishing type：Research paper (other academic)   Publisher：Japanese Society of Tribologists  

<p>Microfluidic devices are technologies that integrate micro- and nano-meter sized structures in a microchannel using a microfabrication technique. In this article, I focused on the fabrication process of our developed microfluidic device which is based on the principle of size exclusion chromatography for DNA separation. Since this device has microfence structures and nanoslit structures in a microchannel, its fabrication process consists of a photolithography and a reactive ion etching for creating the microfence structures and a focused ion beam milling for creating the nanoslit structures. Additionally, I introduced the experimental results of DNA separation using our fabricated microfluidic device. Beyond the research field of analytical chemistry, microfluidic devices have been utilized to other research fields such as rheology for the measurement of viscosity and flow distribution of liquids. I hope that this article will be of interest to the readership in the research field of tribology.</p>

DOI： 10.18914/tribologist.66.10_762

CiNii Research

Language：Japanese   Publishing type：Research paper (other academic)   Publisher：Japanese Society of Tribologists  

DOI： 10.18914/tribologist.66.10_737

CiNii Research

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1063/5.0046939

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：{IOP} Publishing  

DOI： 10.35848/1882-0786/abd199

Scopus

Other Link： https://iopscience.iop.org/article/10.35848/1882-0786/abd199/pdf

Language：Japanese   Publishing type：Research paper (other academic)   Publisher：The Japan Society of Mechanical Engineers  

<p>2-methacryloyloxyethyl phosphorylcholine (MPC) polymer is a promising coating material for extending the useful life of artificial joints due to its biocompatibility and lubricity. Especially, the hydrated brush-like MPC polymer film showed a low coefficient of friction. However, the mechanism of the lubricity is not fully understood. Friction coefficients of the MPC polymer films showed dependency on the shear gap, which must be caused by the thickness dependence of the film's mechanical properties (viscoelasticity). However, due to the thin film thickness (around 100 nm), it was difficult to measure the viscoelasticity. Thus, this research aimed to measure the hydrated MPC polymer brush film's viscoelasticity and elucidate its gap dependency. We established a measurement method that realizes simultaneous measurement of shear viscoelasticity and film thickness.</p>

DOI： 10.1299/jsmeiip.2021.iip1b1-4

CiNii Research

Language：Japanese   Publishing type：Research paper (other academic)   Publisher：The Japan Society of Mechanical Engineers  

<p>The lubrication phenomena of lubricants confined in a nanometer-sized gap are different from those in the bulk state. Clarifying the mechanism of them requires the method to measure the lubricant flow in the nanometer-sized gap. Therefore, we proposed the method to measure the lubricant flow using single molecule tracking of quantum dots with the fluorescence microscope. A single quantum dot has the diameter of several tens of nm and can be applied to measure the lubricant flow in nanometer-sized gap. In this study, we tried to measure the squeeze flow of lubricants in micrometer-sized gap to verify the validity of our proposed method. Our obtained velocities of the squeeze flow were good agreement with those of theoretical model, that indicated the validity of our method.</p>

DOI： 10.1299/jsmeiip.2021.iip1b1-3

CiNii Research

Language：Japanese   Publishing type：Research paper (other academic)   Publisher：The Japan Society of Mechanical Engineers  

<p>To realize heat-assisted magnetic recording (HAMR), which can largely increase the recording density of hard disk drives, it is crucial to ensure the reliability and durability of the head disk interface (HDI) that involves high temperature and high-speed shear. In this study, we performed reactive molecular dynamics simulations to clarify the effects of water and oxygen molecules on the decomposition of nanometer-thick perfluoropolyether D-4OH films that lubricate the HDI of HAMR. From the simulation results, we found that water molecules accelerate the decomposition of D-4OH and this effect is suppressed by the presence of oxygen molecules. We also found that high normal pressures and concentrations of water and oxygen molecules lead to fast decomposition of D-4OH molecules.</p>

DOI： 10.1299/jsmeiip.2021.iip2a3-3

CiNii Research

Language：Japanese   Publishing type：Research paper (other academic)   Publisher：The Japan Society of Mechanical Engineers  

<p>High performance environment-friendly organic friction modifier (OFM) additives are crucial for reducing energy loss and greenhouse gases due to friction and wear. In this study, we designed and synthesized a new type of TEMPO-based OFMs which contain a cyclic structure and free radical. In addition to friction and wear measurements, surface adsorption characteristics of the OFMs were measured with quartz crystal microbalance (QCM). We confirmed that Amide-TEMPO exhibits better friction and wear reduction effect than the conventional glyceryl monooleate. The friction coefficient correlated negatively with the adsorption equilibrium constant, but it showed no correlation with the adsorption density. The anti-wear performance showed no correlation with both adsorption equilibrium constant and adsorption density, suggesting that it is difficult to interpret the wear characteristics simply from the static adsorption characteristics measured by QCM.</p>

DOI： 10.1299/jsmeiip.2021.iip1b1-2

CiNii Research

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1007/s10404-020-02392-w

Scopus

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1021/acs.jpcc.0c06486

Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.triboint.2019.105980

Web of Science

Scopus

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

In this study, we stretched and immobilized a 48.5 kbp-DNA molecule using a pressure flow and a gas-liquid interface movement in a microchannel. A chip device with a straight microchannel was fabricated by transfering Si mold created by a photolithography to PDMS. The depth and width of the microchannel were 2 μm and 100 μm, respectively. We controlled the velocities of the pressure flow and the gas-liquid interface by controlling applied pressures into the microchannel in order to investigate the dependence of stretched rate of the DNA molecule on the velocities. We measured the sizes of stretched and immobilized DNA molecules in the microchannel at each applied pressure by analysing the fluorescent images obtained using a fluorescence microscope. We indicated that the increase of the applied pressure improved the stretched rate of DNAs and achieved the stretched rate of 70 % under the condition of 1150 μm / s (600 mbar).

DOI： 10.1299/jsmeiip.2020.2c06

CiNii Research

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

<p>For reading out genomic information from a single molecule of DNA, it is required to establish a DNA extension method that stretches a DNA molecule existing in a random coil state in a solution. To achieve highly stretched DNA molecules, we utilized and experimentally verified the effect of hydrodynamic drag force and electric field gradient in addition to the effect of nano-confinement; channels heights smaller than the persistence length of DNA molecules. In our experimental results, we revealed that the higher the migration velocity, the higher the elongation rate of DNA molecules. Moreover, by comparing the elongation rate of molecules measured in rectangular and taper-shaped nanoslits, we were able to achieve a higher degree of elongation in the latter type, which had the electric field gradient.</p>

DOI： 10.1299/jsmemecj.2020.j13115

CiNii Research

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

DOI： 10.1299/jsmemecj.2020.j13121

CiNii Research

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

<p>Coarse-grained molecular dynamics simulations were performed to compare the adsorption of organic friction modifier (OFM) added in lubricating oil to flat and corrugated surfaces. Stearic acid, dodecane, and hematite were used as the OFM, lubricating oil, and solid surfaces, respectively. The simulation results showed that the increase in the surface number density of adsorbed stearic acid molecules in 100 ns simulations at 353 K was approximately four times faster on the corrugated surface than on the flat surface. We infer that surface roughness may promote adsorption of OFM additives, owing to the enhanced liquid–solid interactions at the corners formed between adjacent layers of solid surfaces.</p>

DOI： 10.1299/jsmemecj.2020.j13109

CiNii Research

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

<p>To achieve reliable heat-assisted magnetic recording (HAMR), it is crucial to understand the decomposition of perfluoropolyether (PFPE) lubricant films. In this study, we performed reactive all-atom molecular dynamics simulations to investigate the thermal decomposition of PFPE D-4OH using our original ReaxFF force field. The results showed that the thermal decomposition of D-4OH molecules is mainly attributed to the dissociation of C–O bond in the polar end groups and the dissociated fragments transfer from the disk to head and form smears. On the other hand, by quantifying the decomposition time constants at 700 and 800 K, we infer that the thermal decomposition of D-4OH films hardly occurs within the HAMR heating time of ~1 ns.</p>

DOI： 10.1299/jsmemecj.2020.s16102

CiNii Research

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

To achieve effective lubrication of head-disk interface in heat-assisted magnetic recording (HAMR),
mechano-chemical decomposition of nonpolar and polar perfluoropolyether (PFPE) lubricant films, i.e., Z, Z-tetraol, Demnum, and D-4OH, was investigated using reactive molecular dynamics. By fitting with quantum calculation results, the reactive force field (ReaxFF) for PFPE was developed, allowing simulation of chemical reactions of PFPE lubricants. The results showed that at a temperature of 700 K, pure thermal decomposition of PFPE hardly occurs within the nanosecond heating time of HAMR, whereas mechano-chemical decomposition is highly possible to occur when normal pressure and shear are applied by the head and disk. We confirmed that thermal decomposition is mainly caused by the dissociation of C–O bond at the polar end groups and mechano-chemical decomposition is caused by dissociation of C–O bonds at both the polar end groups and main chains.

DOI： 10.1299/jsmeiip.2020.1a06

CiNii Research

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

DOI： 10.1299/jsmemecj.2020.j13112

CiNii Research

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

Measurement of the viscosity of the lubricant in the minute gap is important for elucidating the boundary and mixed lubrication characteristics. It has become clear that the lubricant has a specific viscosity depending on the small gap. Since the viscosity depends on the gap, measurement at a constant (uniform) gap in the measurement region was essential, but it was difficult with a gap of the order of 10 nm. In this study, we propose a method for measuring the viscosity of lubricant in a uniform small gap by combining microfluidic device and fluorescence correlation spectroscopy.

DOI： 10.1299/jsmeiip.2020.2c08

CiNii Research

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

<p>2-Methacryloyloxyethyl phosphorylcholine (MPC) polymer is used as coating material on artificial joint for its hydrated lubricity. In order to elucidate the mechanism of the hydrated lubrication, in this research, we measure the shear viscoelasticity of hydrated MPC polymer films by using a fiber wobbling method (FWM). Simultaneously, we measure the shearing gap by combining microscope underneath the FWM setup and observing the interference fringe. We found that both viscosity and elasticity increased along with the decreasing of gap width. However, the MPC polymer showed a transition from viscous dominant to elastic dominant when the gap is smaller than a certain gap width. This implies that MPC films reduce friction as a low viscos fluid in large shearing gaps and prevent contact between surfaces in small gaps for reducing friction and wear. This may explain the mechanism of hydrated lubrication of MPC film coated on a surface of artificial joint.</p>

DOI： 10.1299/jsmemecj.2020.j13111

CiNii Research

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

Nanopore sequencer is expected as a core technology for realizing medical treatment based on genome information. In order to improve the analysis efficiency, it is necessary to be able to analyze a large molecular size genomic DNA (large molecular weight DNA) with one molecule. Large molecular weight DNA has a random coil structure in a stable state. Therefore, it is indispensable to establish the technology to extend the random coil-shaped DNA molecule linearly in order to realize the analysis with the nanopore sequencer. In this study, we experimentally verified the effect of migration conditions on the elongation rate of DNA molecules that elongate during electrophoresis in a nanoslit. The results showed that DNA elongation was significantly affected not only by the geometric conditions of the flow channel, but also by the electric field distribution (position within the nanoslit) and the migration speed.

DOI： 10.1299/jsmeiip.2020.2c05

CiNii Research

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

<p>When a DNA molecule passes through a nanochannel which depth is smaller than its size, the molecule is trapped in front of the nanochannel based on an entropy trap. Trapping time τ is a parameter to characterize the entropy trap and measuring trapping time τ accurately is required to design DNA separation and concentration methods based on the entropy trap. In this study, we proposed an experimental measurement method of trapping time τ using DNA concentration method. We fabricated a chip device with a nanogap of 25-nm depth in a microchannel using microfabrication technique and succeeded in determining the voltage V dependence of trapping time τ of 48.5-kbp DNA by experiments with 0.8 - 1.2 V.</p>

DOI： 10.1299/jsmemnm.2019.10.21pm1pn319

CiNii Research

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

On-chip concentration is a method of concentrating biomolecules using a nanometer-sized structure created into a microchannel, which is effective for improving detection sensitivity for microfluidic devices. As an on -chip concentration method for DNA molecules, we proposed a concentration method using nanoslit, which was a gap smaller than a diameter of a single molecule. Since this concentration method was based on the principle of entropy trap, its concentration amount depended on applied voltage. In this study, we proposed a theoretical model of concentration using nanoslit and determined an optimal voltage at which maximizing the concentration amount. We fabricated a chip device with 25 nm-depth nanoslit using microfabrication technique and experimentally verified the validity of our model. We achieved the concentration of λ DNA molecules at 17 times when we applied 0.6 V for 15 s.

DOI： 10.1299/jsmeiip.2019.2c01

CiNii Research

Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.7567/JJAP.57.027002

Web of Science

Scopus

Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.7567/JJAP.56.127001

Web of Science

Scopus

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

Size separation of large DNA molecules (10 kbp – 1000 kbp) is one of the fundamental procedures for identifying bacterium’s genotypes, which should be fast for quick defection of infectious diseases. In our conventional study, we developed an electrophoresis microchip based on size exclusion chromatography. This separation has an advantage that it does not cause large deformation of DNA, which is important for separation of large DNAs because they can be easily fragmented. We achieved separation of large DNAs (48 kbp + 166 kbp) driven by a direct electric field as electrophoretic condition of DNA. However, it caused long separation time (3000 s) because DNAs migration was slow due to low applied voltage for the separation. In this study, we achieved faster separation of DNAs using a pulsed electric field under which applied voltage can be higher.

DOI： 10.1299/jsmeiip.2017.e-01

CiNii Research

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

On-chip concentration of samples using nanometer-sized structures fabricated in a microchannel is an effective method to improve detection sensitivity in μTAS. We proposed on-chip concentration of DNA samples using a nano-slit, which is a channel with a depth smaller than a diameter of DNA molecule. The concentration is based on an entropy trap at the boundary between the microchannel and the nano-slit. Therefore, concentration is achieved only by adjusting applied voltages. In this study, we verified the feasibility and the performances of the proposed concentration experimentally. When we applied 0.3 V for 100 s by using 30-nm deep nano-slit, we succeeded in concentration of λ DNA at 25 times the concentration rate.

DOI： 10.1299/jsmemnm.2017.8.pn-106

CiNii Research

Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (international conference proceedings)  

DOI： https://doi.org/10.1299/jsmemipe.2015._MoB-2-4-1

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

Size separation of large DNA molecules (10 kbp – 1000 kbp) is one of the fundamental procedures for identifying bacterium&amp;rsquo;s genotypes, which should be fast for quick defection of infectious diseases. In our conventional study, we developed an electrophoresis microchip based on size exclusion chromatography. This separation has an advantage that it does not cause large deformation of DNA, which is important for separation of large DNAs because they can be easily fragmented. We achieved separation of large DNAs (48 kbp + 166 kbp) driven by a direct electric field as electrophoretic condition of DNA. However, it caused long separation time (3000 s) because DNAs migration was slow due to low applied voltage for the separation. In this study, we achieved faster separation of DNAs using a pulsed electric field under which applied voltage can be higher.

DOI： 10.1299/jsmeiip.2017.E-01

CiNii Research

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

On-chip concentration of samples using nanometer-sized structures fabricated in a microchannel is an effective method to improve detection sensitivity in μTAS. We proposed on-chip concentration of DNA samples using a nano-slit, which is a channel with a depth smaller than a diameter of DNA molecule. The concentration is based on an entropy trap at the boundary between the microchannel and the nano-slit. Therefore, concentration is achieved only by adjusting applied voltages. In this study, we verified the feasibility and the performances of the proposed concentration experimentally. When we applied 0.3 V for 100 s by using 30-nm deep nano-slit, we succeeded in concentration of λ DNA at 25 times the concentration rate.

DOI： 10.1299/jsmemnm.2017.8.pn-106

CiNii Research

Event date： 2024.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：岡山大学　津島キャンパス  

Event date： 2024.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：岡山大学　津島キャンパス  

Event date： 2024.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：岡山大学　津島キャンパス  

Event date： 2024.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：岡山大学　津島キャンパス  

Event date： 2023.11

Language：English   Presentation type：Poster presentation  

Venue：Keio Plaza Hotel Sapporo, Sapporo, Japan  

Event date： 2023.11

Language：English   Presentation type：Oral presentation (general)  

Venue：Keio Plaza Hotel Sapporo, Sapporo, Japan  

Event date： 2023.11

Language：English   Presentation type：Poster presentation  

Venue：Keio Plaza Hotel Sapporo, Sapporo, Japan  

Event date： 2023.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Fukuoka International Congress Center, Fukuoka, Japan  

Event date： 2023.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Fukuoka International Congress Center, Fukuoka, Japan  

Event date： 2023.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Fukuoka International Congress Center, Fukuoka, Japan  

Event date： 2023.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Fukuoka International Congress Center, Fukuoka, Japan  

Event date： 2023.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Fukuoka International Congress Center, Fukuoka, Japan  

Event date： 2023.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京都立大学　南大沢キャンパス  

Event date： 2023.6 - 2023.7

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：名古屋国際会議場  

Event date： 2023.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：国立オリンピック記念青少年総合センター  

Event date： 2023.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：国立オリンピック記念青少年総合センター  

Event date： 2023.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：国立オリンピック記念青少年総合センター  

Event date： 2023.5

Language：English   Presentation type：Oral presentation (general)  

Venue：Long beach,Carifornia USA  

Event date： 2023.5

Language：English   Presentation type：Oral presentation (general)  

Venue：Long beach,Carifornia USA  

Event date： 2023.5

Language：English   Presentation type：Oral presentation (general)  

Venue：Long beach,Carifornia USA  

Event date： 2023.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州工業大学　戸畑キャンパス   Country：Japan  

Event date： 2023.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州工業大学　戸畑キャンパス   Country：Japan  

Event date： 2023.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州工業大学　戸畑キャンパス   Country：Japan  

Event date： 2023.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州工業大学　戸畑キャンパス   Country：Japan  

Event date： 2023.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州工業大学　戸畑キャンパス   Country：Japan  

Event date： 2023.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州工業大学　戸畑キャンパス   Country：Japan  

Event date： 2023.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州工業大学　戸畑キャンパス   Country：Japan  

Event date： 2023.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州工業大学　戸畑キャンパス   Country：Japan  

Event date： 2023.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州工業大学　戸畑キャンパス   Country：Japan  

Event date： 2023.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州工業大学　戸畑キャンパス   Country：Japan  

Event date： 2023.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州工業大学 戸畑キャンパス   Country：Japan  

Event date： 2023.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州工業大学 戸畑キャンパス   Country：Japan  

Event date： 2023.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州工業大学 戸畑キャンパス   Country：Japan  

Event date： 2023.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州工業大学 戸畑キャンパス   Country：Japan  

Event date： 2023.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州工業大学 戸畑キャンパス   Country：Japan  

Event date： 2023.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州工業大学 戸畑キャンパス   Country：Japan  

Event date： 2023.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州工業大学 戸畑キャンパス   Country：Japan  

Event date： 2023.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州工業大学 戸畑キャンパス   Country：Japan  

Event date： 2023.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州工業大学 戸畑キャンパス   Country：Japan  

Event date： 2023.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州工業大学 戸畑キャンパス   Country：Japan  

Event date： 2022.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福井市フェニックスプラザ   Country：Japan  

Event date： 2022.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福井市フェニックスプラザ   Country：Japan  

Event date： 2022.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福井市フェニックスプラザ   Country：Japan  

Event date： 2022.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福井市フェニックスプラザ   Country：Japan  

Event date： 2022.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福井市フェニックスプラザ   Country：Japan  

Event date： 2022.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福井市フェニックスプラザ   Country：Japan  

Event date： 2022.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福井市フェニックスプラザ   Country：Japan  

Event date： 2022.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福井市フェニックスプラザ   Country：Japan  

Event date： 2022.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福井市フェニックスプラザ   Country：Japan  

Event date： 2022.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福井市フェニックスプラザ   Country：Japan  

Event date： 2022.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福井市フェニックスプラザ   Country：Japan  

Event date： 2022.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福井市フェニックスプラザ   Country：Japan  

Event date： 2022.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福井市フェニックスプラザ   Country：Japan  

Event date： 2022.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福井市フェニックスプラザ   Country：Japan  

Event date： 2022.9

Language：Japanese   Presentation type：Poster presentation  

Venue：富山大学五福キャンパス   Country：Japan  

Event date： 2022.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：富山大学五福キャンパス   Country：Japan  

Event date： 2022.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：富山大学五福キャンパス   Country：Japan  

Event date： 2022.9

Language：Japanese   Presentation type：Poster presentation  

Venue：富山大学五福キャンパス   Country：Japan  

Event date： 2022.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Nagoya University, Nagoya, Japan   Country：Japan  

Event date： 2022.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Nagoya University, Nagoya, Japan   Country：Japan  

Event date： 2022.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Nagoya University, Nagoya, Japan   Country：Japan  

Event date： 2022.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Nagoya University, Nagoya, Japan   Country：Japan  

Event date： 2022.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Nagoya University, Nagoya, Japan   Country：Japan  

Event date： 2022.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Nagoya University, Nagoya, Japan   Country：Japan  

Event date： 2022.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Nagoya University, Nagoya, Japan   Country：Japan  

Event date： 2022.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Nagoya University, Nagoya, Japan   Country：Japan  

Event date： 2022.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Nagoya University, Nagoya, Japan   Country：Japan  

Event date： 2022.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Nagoya University, Nagoya, Japan   Country：Japan  

Event date： 2022.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Nagoya University, Nagoya, Japan   Country：Japan  

Event date： 2022.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Nagoya University, Nagoya, Japan   Country：Japan  

Event date： 2022.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Nagoya University, Nagoya, Japan   Country：Japan  

Event date： 2022.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Nagoya University, Nagoya, Japan   Country：Japan  

Event date： 2022.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Nagoya University, Nagoya, Japan   Country：Japan  

Event date： 2022.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Nagoya University, Nagoya, Japan   Country：Japan  

Event date： 2022.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Nagoya University, Nagoya, Japan   Country：Japan  

Event date： 2022.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Nagoya University, Nagoya, Japan   Country：Japan  

Event date： 2022.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Nagoya University, Nagoya, Japan   Country：Japan  

Event date： 2022.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Nagoya University, Nagoya, Japan   Country：Japan  

Event date： 2022.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Nagoya University, Nagoya, Japan   Country：Japan  

Event date： 2022.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Nagoya University, Nagoya, Japan   Country：Japan  

Event date： 2022.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Nagoya University, Nagoya, Japan   Country：Japan  

Event date： 2022.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Nagoya University, Nagoya, Japan   Country：Japan  

Event date： 2022.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Nagoya University, Nagoya, Japan   Country：Japan  

Event date： 2022.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Nagoya University, Nagoya, Japan   Country：Japan  

Event date： 2022.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Nagoya University, Nagoya, Japan   Country：Japan  

Event date： 2022.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Nagoya University, Nagoya, Japan   Country：Japan  

Event date： 2022.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Nagoya University, Nagoya, Japan   Country：Japan  

Event date： 2022.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Nagoya University, Nagoya, Japan   Country：Japan  

Event date： 2022.7

Language：English   Presentation type：Oral presentation (general)  

Venue：Lyon, France   Country：France  

Event date： 2022.7

Language：English   Presentation type：Oral presentation (general)  

Venue：Lyon, France   Country：France  

Event date： 2022.7

Language：English   Presentation type：Oral presentation (general)  

Venue：Lyon, France   Country：France  

Event date： 2022.7

Language：English   Presentation type：Oral presentation (general)  

Venue：Lyon, France   Country：France  

Event date： 2022.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：国立オリンピック記念青少年総合センター   Country：Japan  

Event date： 2022.5

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2022.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：国立オリンピック記念青少年総合センター   Country：Japan  

Event date： 2022.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：国立オリンピック記念青少年総合センター   Country：Japan  

Event date： 2022.5

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2022.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：国立オリンピック記念青少年総合センター   Country：Japan  

Event date： 2022.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：国立オリンピック記念青少年総合センター   Country：Japan  

Event date： 2022.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：国立オリンピック記念青少年総合センター   Country：Japan  

Event date： 2022.3

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2022.3

Event date： 2022.3

Event date： 2022.3

Event date： 2022.3

Event date： 2022.3

Event date： 2022.3

Event date： 2021.10

Presentation type：Oral presentation (general)  

Event date： 2021.10

Presentation type：Oral presentation (general)  

Event date： 2021.10

Presentation type：Oral presentation (general)  

Event date： 2021.10

Presentation type：Oral presentation (general)  

Event date： 2021.9

Presentation type：Oral presentation (general)  

Event date： 2021.9

Presentation type：Oral presentation (general)  

Event date： 2021.9

Presentation type：Oral presentation (general)  

Event date： 2021.9

Presentation type：Oral presentation (general)  

Event date： 2021.9

Presentation type：Oral presentation (general)  

Event date： 2021.6

Event date： 2021.5

Event date： 2021.5

Event date： 2021.5

Event date： 2021.5

Event date： 2021.5

Event date： 2021.3

Event date： 2021.3

Event date： 2021.3

Event date： 2021.3

Event date： 2021.3

Event date： 2020.11

Event date： 2020.11

Event date： 2020.9

Language：Japanese   Presentation type：Oral presentation (general)  

Event date： 2020.9

Event date： 2020.9

Event date： 2020.9

Event date： 2020.9

Event date： 2020.3

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2020.3

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2020.3

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2020.3

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2019.11

Language：Japanese   Presentation type：Poster presentation  

Country：Japan  

Event date： 2019.10

Language：English   Presentation type：Poster presentation  

Country：Japan  

Event date： 2019.10

Language：English   Presentation type：Poster presentation  

Country：Japan  

Event date： 2019.10

Language：English   Presentation type：Oral presentation (general)  

Country：United States  

Event date： 2019.5

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2019.5

Language：Japanese   Presentation type：Oral presentation (invited, special)  

Country：Japan  

Event date： 2019.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東洋大学　川越キャンパス   Country：Japan  

Event date： 2018.11

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2018.11

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2018.11

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2017.10 - 2017.11

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2017.3

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2016.11

Language：English   Presentation type：Poster presentation  

Country：Japan  

Event date： 2016.3

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2015.11

Language：English   Presentation type：Poster presentation  

Country：Japan  

Event date： 2015.6

Language：English   Presentation type：Oral presentation (general)  

Venue：Kobe, Japan   Country：Japan  

Event date： 2014.9

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan