FUKUZAWA LAB. Nagoya University
nanosensing engineering
NANO-SENSING ENGINEERING
Nano-sensing engineering is the research field that plays an essential role in improving the precision and functionality of machines on the nanoscale. Advances in material engineering and processing technologies have made it possible to design devices in the nanoscale, that is essential for advanced machines. However, physical phenomena in the nanoscale are quite different from those in the macroscale. Their phenomena need to be clarified. For example, it is necessary to clarify the physical phenomena in the nanoscale sliding gap between mechanical elements to achieve further fuel efficiency in automobile engines' lubrication system. If nanomachines are developed, revolutionary machines such as microscopic medical robots will be realized; however, it is challenging to clarify the nanoscale phenomena and characteristics. Nano-sensing engineering is essential for further improving mechanical engineering and is the research field that will cause breakthroughs in the next generation of mechanical engineering. For this reason, many Nobel Prizes have been awarded in the field of nano-sensing engineering (e.g., electron microscopy, scanning tunneling microscopy, MALDI, super-resolution microscopy, etc.).
We develop nano-sensing systems and devices based on our original ideas, such as an ellipsometric microscope that can visualize dynamics of fluid phenomena in the nanoscale in situ, a micromechanical probe that can measure mechanical properties in the nanoscale using the combination with an atomic force microscope, mechanical sensing system that can measure mechanical properties with ultra-high sensitivity at the nN level. Using our advanced sensing technology, we aim to clarify the nanoscale phenomena and realize ultra-precision machines based on new principles. Additionally, since the measurement signals obtained using nano-sensing are very weak, we expect to improve sensing sensitivity by applying information technology. By collaborating with the Graduate School of Informatics (Ohka Lab. and Zhang Lab.), we aim to innovate our sensing technology by applying information science technologies such as machine learning and artificial intelligence (AI) to process the measurement signals optimize the control conditions.
(From the left, an experiment with an ellipsometry microscope, a micromechanical probe developed in our laboratory, and an experiment in a cleanroom. ）
Research themes
・Development of high-sensitive nanomechanical sensing system with force sensitivity of 0.1 nN
・Micromechanical probes for surface analysis and manipulation in nanoscale
・Ellipsometric microscopy for visualization of nanoscale dynamics of fluid phenomena
Research achievements
・Fiber wobbling method for dynamic viscoelastic measurement of liquid lubricant confined in molecularly narrow gaps, Tribology Letters, Vol. 30, 2008.6, pp. 177-189
・Design Principle of Micro-Mechanical Probe for Lateral-Deflection-Controlled Friction Force Microscopy, Microsystem Technologies, Vol. 22, 2016.5, pp. 1181-1188
・Design Principle of Micromechanical Probe with an Electrostatic Actuator for Friction Force Microscopy, Microsystems Technologies, Vol. 19, 2013.9, pp. 1567-1572
・Measurement of nanometer-thick lubricating films using ellipsometric microscopy, Tribology International, Vol. 122, 2018.6, pp. 8-14
・Extension of the measurement range of lubrication gap shape using vertical-objective-type ellipsometric microscopy with two compensator angles, Tribology International, Vol. 142, 2020.2, 105980, 8 pages
biosensing engineering
BIOSENSING ENGINEERING
Biosensing technology for biomolecules (e.g., DNA and proteins, etc.) at the single-molecule level is required to improve medical and biotechnology research. Biosensing technology has been based on chemical and biological analysis, but the single-molecule level analysis was not easy to achieve. Therefore, single-molecule level analysis has been realized by manipulating it with mechanical techniques. For example, μTAS (Micro total analysis system), which integrates many biochemical processes (e.g., reactors, filters, etc.) required for medical and biological research into a microchannel, can rapidly analyze biomolecules at the single-molecule level. We realize μ-TAS using our unique micro-and nano-structures formed in microchannels for single-molecule analysis of DNA molecules. Our research includes studies of biocompatible polymer to control the surface of artificial joints and medical devices.
On the other hand, it is necessary to clarify biomolecules and polymer molecules' behavior at the nanoscale to design biosensing devices and systems. However, their behavior in the nanoscale is quite different from that of molecules in the bulk state. Therefore, we aim to clarify the behavior and properties of biomolecules and polymers in the nanoscale using our developed nano-sensing devices and systems and to establish a new mechanical design theory. Also, since the measurement signals obtained using biosensing are so weak, we challenge improving sensitivity by applying information technology.
(DNA analysis chip, microstructure for DNA separation formed in a microchannel, high durability of an artificial joint by nanofluid engineering)
Research themes
・Development of microfluidic devices for high-precision, high-speed DNA analyses
・Single-molecule DNA sensing using super-resolution imaging in microfluidic devices
・Analysis of flow properties with biocompatible polymers for medical devices and artificial
Research achievements
・Separation of Large DNA Molecules by Applying Pulsed Electric Field to Size Exclusion Chromatography-based Microchip, Japanese Journal of Applied Physics, 57, 027002, 2018.1, 8 pages
・Optimization of Applied Voltages for On-chip Concentration of DNA Using Nanoslit, Naoki Azuma, Japanese Journal of Applied Physics, 56, 127001, 2017. 11, 8 pages
・Anisotropic shear viscosity of photoaligned liquid crystal confined in sub-micron-to-nanometer-scale gap widths revealed with simultaneously measured molecular orientation, Langmuir, 2015.9, Vol. 31, pp. 11360-11369
tribology
TRIBOLOGY
Pauli said, "God made solids, but surfaces were the work of the devil !". This means that surfaces are so physically and chemically complex that we cannot explain them as simple theoretical systems. This is because the surfaces' properties depend much on the dynamics and property of a single molecule. In other words, molecular-level analysis is essential to clarify the surfaces. Nano-sensing has enabled highly sensitive measurements at the molecular level, making it possible to clarify and control the surfaces.
There are two types of mechanical phenomena on the surfaces: friction and adhesion. Friction is the mechanical interaction in the horizontal direction to the surface, and adhesion is vertical. Tribology is the research field to control these phenomena technically. The history of tribology is ancient, as seen in the wall paintings depicting the Egyptian pyramids' construction (Leonardo da Vinci is known as a pioneer in tribology). Developments in nano-sensing have made it possible to control surface friction and adhesion at the molecular level. Therefore, in the 1990s, a new research field called nanotribology was born. In other words, nanotribology is a science and technology that uses molecular-level technology to create innovative functional surfaces, such as surfaces with ultra-low friction, surfaces that efficiently transfer energy, and surfaces that do not cause wear. This makes it possible to realize high energy efficiency and high durability of mechanical systems. Nanotribology has a wide range of applications in mechanical systems such as automobile engines, railroads, artificial joints, power generation turbines, satellites, smartphone memory, and hard disk drives. We challenge to create surfaces with ultra-low friction, high durability, and innovative functions from the molecular level using our advanced nano-sensing technology. Our research results are expected to improve the fuel efficiency of automobile engines, increase smartphone memory capacity, realize next-generation hard disk drives, and increase artificial joints' service life.
(From left, HDD nanotribology (image), engine nanotribology (image), fine surface structure produced by nanoimprint)
Research themes
・Development of advanced tribology systems for next-generation information recording devices
・Lubrication technology for ultra-low fuel consumption engine
・Nanofabrication technologies such as nanomachines and nanoimprint lithography
Research achievements
・Enhanced Viscoelasticity of Polyalphaolefins Confined and Sheared in Submicron-to-nanometer-sized Gap Range and Its Dependence on Shear Rate and Temperature, Tribology International, Vol. 120, 2018.4, pp. 210-217
・Real-time Observation of Molecularly Thin Lubricant Films on Head Sliders Using Rotating-Compensator-Based Ellipsometric Microscopy, IEEE Transactions on Magnetics, Vol. 53, 2017.11, pp. 1-4
・Measurement of Viscoelasticity of UV photoresist used for nanoimprint lithography under confinement in nanometer-sized gaps, Japanese Journal of Applied Physics, Vol. 56, 06GL02, 2017.5, 6 pages
・Measurement of Thickness Distribution of Molecularly Thin Lubricant Films on Head Sliders Using Ellipsometric Microscopy, IEEE Transactions on Magnetics, Vol. 52, 2016. 7, 3300904, 4 pages
Molecular dynamics simulation
MOLECULAR DYNAMICS SIMULATION
To utilize the phenomena measured using nano-sensing and bio-sensing in the design of next-generation machines, it is necessary to understand the mechanisms correctly. However, nanoscale phenomena cannot be explained by conventional theories and laws. Therefore, molecular dynamics simulation becomes a powerful tool. Molecular dynamics simulation is a method of computational science that represents the behavior of a single atom or molecule on a computer. Suppose we can represent a real system using simulation. In that case, we can clarify complex phenomena at the nanoscale from the dynamics of individual atoms and molecules and use this information to design ultra-precise or micro machines.
In collaboration with Zhang Lab. at the Graduate School of Informatics, we attempt to clarify the nanoscale phenomena using molecular dynamics simulations. In the simulations, a lot of parameters must be determined to represent the properties of molecules. In conventional simulations, these were determined based on our experience, which significantly reduced the efficiency. Therefore, we challenge to determine the optimal parameters using information techniques such as machine learning. We simulate the dynamics of individual molecules and the chemical reactions and succeeded in analyzing complex fluid properties in the nanoscale, which are difficult to analyze by conventional simulations. We try to clarify the nanoscale phenomena by combining our experimental method of nano-sensing and bio-sensing with the analytical method of molecular dynamics simulation. We aim to create a new ultra-precision mechanical engineering that realizes manufacturing from the molecular level.
(From the left: Analysis of the behavior of polymers on solid surfaces by simulation, analysis of the behavior of polymers sheared at the nanoscale)
Research themes
・Mechanical analysis at the atomic and molecular level using supercomputers
・Analysis of molecular behavior and chemical reactions through molecular dynamics simulation using AI
Research achievements
・Simultaneous in situ Measurements of Contact Behavior and Friction to Understand the Mechanism of Lubrication with Nanometer-thick Liquid Lubricant Films, Tribology International, Vol. 127, 2018.11, pp. 138-146
・Is the Trend of Stribeck Curves Followed by Nano-Lubrication with Molecularly Thin Liquid Lubricant Films?, Tribology International, Vol. 119, 2018.3, pp. 82-87
・Molecular Dynamics Simulations of Diffusion of Submonolayer Polar Liquid Lubricant Films on Solid Surfaces, Microsystem Technologies, Vol. 22, 2016.6, pp. 1285-1290
Main research equipment
Research facilities
・Atomic force microscope
・Scanning ellipsometer
・Optical surface analyzer
・Microscopic Fourier transform infrared spectrometer
・Contact angle measurement system
・Electron microscope
・Anodic bonding equipment
・Carbon dioxide laser
・Friction Testing Machine
・Vacuum Evaporation Equipment
・Fluorescence Microscope System
・Fiber Wobbling Method (Original)
・Ellipsometric Microscope (Original)
・Ultra-low friction tester (Original)
Uniquely developed device
・Fiber wobbling method
・Ellipsometry microscope
・Ultra small load friction tester