Ohki Labo. Research Activities

Polymer Gr. (Polymer material) 1. Polymer Gr. (Polymer material) Environment problems, Global heating, Biodegradability, Environment problems, Global heating, Biodegradability, Environment-friendly material, Nanocomposite, etc… Environment-friendly material, Nanocomposite, etc… Electronic Device Gr. (MOS Tr. Novel material for 2. Electronic Device Gr. (MOS Tr. Novel material for a gate insulating film) a gate insulating film) High-k material for next-generation electronic device, High-k material for next-generation electronic device, Synchrotron orbit radiation,etc… Synchrotron orbit radiation, etc… Applied Optics Gr. 3. Applied Optics Gr. Biosensor, Photocatalyst, Metamaterial, Biosensor, Photocatalyst, Metamaterial, Optical fiver, Photonic crystal, etc… Optical fiver, Photonic crystal, etc… Reserch Group of Ohki laboratory

Development of environment-friendly materials Polymer Gr. Temperature dependence Electric conduction properties Space charge distribution Breakdown characteristics Ion migration THz spectroscopy Dielectric properties Biodegradable Polymers Nanocomposites Printed circuit boards

Nondisruptive diagnostic method of cable degradation.We look into possible application of broad spectrum impedance spectroscope (BIS). In the future, this data will be of assistance of the standard about evaluating power cable of atomic power plant. Monitoring and diagnostic testing of cable degradation Monitoring and diagnostic testing of cable degradation Offering technical advantagesof high density implementable electronic circuit substrate by polymer nanocomposite technique. Offering technical advantages of high density implementable electronic circuit substrate by polymer nanocomposite technique. The Knowledge Cluster Initiative The Knowledge Cluster Initiative

Made from plant Cycloid type recycling system Polymer with low environmental loads Natural reduction system Compost processing H2OH2O resolved by bacteria Biodegradable Polymers CO 2 The natural world cycle photosynthesis microbe decomposition microbe destruction digestion enzyme saccharide starch cellulose Digestion synthesis chemical synthesis etc Biodegradable Plastics

Polymer nanocomposite and its problem Property changes associated with nanostructuration is influenced by the interface between the polymer and the nano-filler. Polymer nanocomposite (NC ) is a mixture of polymer and nano-sized filler. Effect of nano-filler addition in permittivity ( nanostructuration ) in some NC : decrease in some NC : no change in some NC : increase From where does the property difference come? filler polymer

The increase of leak current by tunneling effect has been caused. The thickness of a gate insulating film has been reduced to approximately 1 nm. Electronic Device Gr.

Crystal defects of LaAlO 3 Problems of high-  gate insulating material Method for detecting crystal defects 2. Electron Paramagnetic Resonance (EPR) 1. Photoluminescence (PL) Fig. LaAlO 3 single crystal (Perovskite structure) Insulating materials have defects defects therein. The defects form a localized level in a forbidden band. The localized level causes leak current.

Photoluminescence (PL) [1] J. Heber et al.,: Z. Phys. 246 (1971) 261. The PL spectral shapes are very similar. R line luminescence of doped Cr 3+ in LaAlO 3 [1] LaAlO 3 Single crystal Cr 3+ impurity Presence of Cr 3+ impurity is indicated by PL. Wavelength [nm]

Electron Spin Resonance (ESR) Crystal field of octahedral symmetry [2] D. Kiro, W. Low and A. Zuman, Paramagnetic Resonance vol 1, ed. W. Low, (New York, Academic, 1962), pp H: Magnetic field H is parallel to direction of （ 111 ）. Angle-resolved EPR spectra of the LaAlO 3 single crystal (111) at room temperature. Angler dependence of the spectrum of Cr 3+ in LaAlO 3. [2] The ESR spectral shapes are very similar. Cr3+ impurity Presence of Cr3+ impurity is indicated by ESR and PL.

Biomolecules can be detected! Proteins, cells, … # Excitation of waveguide mode # Surface plasmon resonance etc… PC Signal converter Analyte Specific adsorption Applied Optics Gr. -Biosensor- Biosensor Analyte

Detector Streptavidin (SA) Waveguide  Polarizer Laser Teflon cuvette Prism Waveguide mode Reflection layer Kretschmann configuration Reflectance 0 1 Incident angle After adsorption Before adsorption Angle shift Biosensing system using a waveguide-mode sensor Our previous research Ex. Detection of streptavidin (A kind of protein) This system : sensitive compared with conventional SPR sensors (~ 40 times). Biotin probe (Vitamin)

Present research (1) Streptavidin (SA) (Transparent substance) SA labeled with Au nanoparticles Ultrasensitive detection of SA by labeling with Au nanoparticles (Au- SA). Present research  Ultrasensitive biomolecular detection Previous method Improved method Au nanoparticles (Opaque)

Immobilization of biotin on the surface Injection of solution (10 pM Au-SA) Measurement of reflectance After 20 hours Experimental procedures Measurement of reflectance Present research (2) 30 o He-Ne laser Polarizer  SiO 2 glass prism SiO 2 glass layer Si layer SiO 2 glass substrate Detector Au-SA Biotin probe Comparison of reflection spectra before and after the Au-SA adsorption.

500 nm Average number density : 2  m -2 Au-SA SEM image of the surface after the adsorption of Au-SA Present research (3)

 Au-SA with a number density of only 2  m -2 can be detected. ○ Before adsorption of Au-SA △ After adsorption of Au-SA Au-SA Ultrasensitive detection of SA by labeling with Au nanoparticles Present research (4)