Kei Takenaka

Silicon-Based Optical Thin-Film Biosensor Array for Real-time Measurements of Biomolecular Interaction

Real-time multi-channel measurements of protein-protein interaction in 1–100 µg/ml antibody solution samples were demonstrated using a reflectometric interference spectroscopy (RIfS) based silicon biochip. Since titanium-oxide film, whose refractive index is 2.2, was chosen for the interference layer of RIfS on the silicon substrate, the layer interference was enhanced in aqueous solutions and the protein-protein interaction on the film could be measured as a shift in interference-peak position in the reflection spectra. To estimate the sensitivity of the sensing system using the RIfS sensor, we simulated the reflection spectra of the biochip. From these results, it was shown that a 0.01-nm shift in the interference-peak position corresponds to a binding amount of protein of approximately 10 pg/mm2. According to this result, the sensitivity of our sensor was estimated to be in the order of 10 pg/mm2 by comparing the simulated and experimental results.

Application of Hybrid Petri Nets for a Drawing Blood Flow from Fingertip.

Our objective of this study are to make a fluid dynamical model and to conduct the flow simulation for obtaining a large amount of drawing blood from a fingertip. The processes of drawing blood are hybrid systems including both the continuity system of blood flow and the discrete systems of cuff pressing and puncture. Therefore, we made the modelling of the fingertip drwaing blood process from the analogy of fluid daynamic tank and pipe systems control using hybrid Petri nets. Using the hybrid Petri nets simulation with cuff pressing and puncture modeled as discrete and blood flow modeled as continuity, we confirmed that the simulation results were agreement with the experimental drawing blood data.

Analysis of particle in liquid using excitation-fluorescence spectral flow cytometer

We have developed a new flow cytometer that can measure the excitation-fluorescence spectra of a single particle. This system consists of a solution-transmitting unit and an optical unit. The solution-transmitting unit allows a sample containing particles to flow through the center of a flow cell by hydrodynamic focusing. The optical unit irradiates particles with dispersed white light (wavelength band: 400–650 nm) along the flow direction and measures their fluorescence spectra (wavelength band: 400–700 nm) using a spectroscopic photodetector array. The fluorescence spectrum of a particle changes with the shift of the wavelength of the excitation light. Using this system, the excitation-fluorescence spectra of a fluorescent particle were measured. Additionally, a homogenized tomato suspension and a homogenized spinach suspension were measured using the system. Measurement results show that it is possible to determine the components of vegetables by comparing measured fluorescence spectra of particles in a vegetable suspension.

Airborne virus detection by a sensing system using a disposable integrated impaction device.

There are many respiratory infections such as influenza that cause epidemics. These respiratory infection epidemics can be effectively prevented by determining the presence or absence of infections in patients using frequent tests. We think that self-diagnosis may be possible using a system that can collect and detect biological aerosol particles in the patients breath because breath sampling is easy work requiring no examiner. In this paper, we report a sensing system for biological aerosol particles (SSBAP) with a disposable device. Using the system and the device, someone with no medical knowledge or skills can safely, easily, and rapidly detect infectious biological aerosol particles. The disposable device, which is the core of the SSBAP, can be an impactor for biological aerosol particles, a flow-cell for reagents, and an optical window for the fluorescent detection of collected particles. Furthermore, to detect the fluorescence of very small collected particles, this disposable device is covered with a light-blocking film that lets only fluorescence of particles pass through a fluorescence detector of the SSBAP. The SSBAP using the device can automatically detect biological aerosol particles by the following process: collecting biological aerosol particles from a patients breath in a sampling bag by the impaction method, labeling the collected biological aerosol particles with fluorescent dyes by the antigen-antibody reaction, removing free fluorescent dyes, and detecting the fluorescence of the biological aerosol particles. The collection efficiency of the device for microspheres aerosolized in the sampling bag was more than 97%, and the SSBAP with the device could detect more than 8.3  ×  10(3) particles l(-1) of aerosolized influenza virus particles within 10 min.