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Tribology measurements for nano-gap and boundary lubrication using optical fiber probe

  • School of Engineering/Graduate School of Engineering
  • Micro-Nano Mechanical Science and Engineering

Shintaro Itoh [Associate professor]

http://ayame.fukuzawa.nuem.nagoya-u.ac.jp/index.html

  • School of Engineering/Graduate School of Engineering
  • Micro-Nano Mechanical Science and Engineering

Kenji Fukuzawa [Professor]

Outline of Seeds

Tribological characteristics (such as frictional properties and viscoelastic properties) of lubricant in nano-gaps and boundary lubrication regime differ from those in a bulk state due to the effect of interaction with solid surfaces. To clarify such an effect, we developed a highly sensitive tribology measurement system that utilizing ball-ended optical fiber probes oscillated in a parallel direction to a sample surface (fiber wobbling method). We can determine the tribological properties of sample with precisely controlled nanometer-sized gap widths by detecting mechanical responses of the probe tip oscillation when it shears the sample. (see figures 1 and 2).

Novelty and originality of this research

Since the optical fiber has high rigidity in the axial direction, we can adjust the gaps precisely; since rigidity is low in the lateral direction, which is the direction of bending deflection of the probe, the friction force measurement is quite sensitive. For the sensitive detection of deflection caused by the friction force acting on the probe tip, we developed original method that uses the fiber as a lens. We attained the 0.1 nm accuracy in of the gap control and 0.01 nN detection limit in the friction force measurement.

Application and research area for Industry collaboration

Viscoelastic measurement of nanometer-thick lubricant films, viscoelastic measurement of fluids in micro to nanometer-sized channels for microTAS design

Key Takeaway

The goal of our research is to develop technologies that realize stable and accurate relative motion that was governed by nanometer-scale phenomena (e.g. boundary lubrication, thin film lubrication).
Our research subjects are creation of functional tribo-surfaces, measurement of mechanical properties of nanometer thick liquid films (picometer-displacement and nanonewton-force measurements), dynamic analysis of nanometer-thick lubricant films using molecular dynamic simulation, and so on.

Keywords

Boundary lubrication, nanometer-thick liquid films, surface measurements and analyses, micromachine, bio-sensing, probe based measurement

Technologies

  • Measurement methods to reveal nanometer-scale mechanical phenomena for nano-tribology
  • Methods for measuring and controlling thickness distribution of nanometer-thick lubricant films
  • Design and fabrication of novel sensing device using MEMS technology
  • Molecular simulation for Micro/nano-mechatronics devices and biomolecule (e.g. DNA) sensing devices.

Equipment

  • Cleanroom (Class 10,000)
  • Scanning probe microscope
  • Optical surface analyzer (OSA)
  • Scanning ellipsometer

Monographs, Papers and Articles

  • Shear thinning of nanometer-thick liquid lubricant films measured at high shear rates, S. Itoh, K. Ishii, K. Fukuzawa, H. Zhang, Tribology Letters, vol. 53, pp. 555-567 (2014)
  • Simultaneously Measuring Lateral And Vertical Forces with Accurate Gap Control for Clarifying Lubrication Phenomena at Nanometer Gap,K. Fukuzawa, K. Hayakawa, N. Matsumura, S. Itoh H. Zhang, Tribology Letters, Vol. 37, pp. 497-505 (2010)