Nonstaining Blood Flow Imaging Using Optical Interference Due to Doppler Shift and Near-Infrared Imaging of Molecular Distribution in Developing Fish Egg Embryos.

In the present study, we successfully obtained nonstaining blood flow images of a developing fish egg embryo using optical interference caused by the Doppler shift. The spectral distribution of light reflected by moving objects such as the heart and red cells was found to be different from that of the incident light because of the Doppler effect. Interference between different frequency components was observed in an interferogram through heterodyne interaction using an imaging-type two-dimensional Fourier spectroscopic system, and information on the intensities of the spectral components was obtained by Fourier transformation. Beat signals with specific frequencies due to the heart beating and blood flow of the fish egg embryo were detected. When the signals were plotted in two dimensions, the heart part and vessel flows were clearly visualized without staining. In addition, near-infrared (NIR) images were produced using absorbance spectra of the molecular vibrations of O-H and C-H groups included in water, hydrocarbons, and aliphatic compounds. Obtaining nonstaining blood flow images using heterodyne optical interference and images of molecular distribution using molecular vibrational information simultaneously manifests an exciting advance in NIR imaging.

Enhanced interference-pattern visibility using multislit optical superposition method for imaging-type two-dimensional Fourier spectroscopy.

A solution is found for the problem of phase cancellation between adjacent bright points in wavefront-division phase-shift interferometry. To this end, a design is proposed that optimizes the visibility of the interference pattern from multiple slits. The method is explained in terms of Fraunhofer diffraction and convolution imaging. Optical simulations verify the technique. The final design can be calculated using a simple equation.

Glucose emission spectra through mid-infrared passive spectroscopic imaging of the wrist for non-invasive glucose sensing.

Non-invasive blood glucose sensing can be achieved using mid-infrared spectroscopy, although no practical device based on this method has yet been developed. Here, we propose mid-infrared passive spectroscopic imaging for glucose measurements from a distance. Spectroscopic imaging of thermal radiation from the human body enabled, for the first time in the world, the detection of glucose-induced luminescence from a distance. In addition, glucose emission spectra of the wrist acquired at regular intervals up to 60 min showed that there was a strong correlation between the glucose emission intensity and blood glucose level measured using an invasive sensor. Thus, the new technology proposed here is expected to be applied to real-time monitoring of diabetic patients to detect hypoglycemic attacks during sleep and to detect hyperglycemia in a population. Moreover, this technology could lead to innovations that would make it possible to remotely measure a variety of substances.

Identification of black microplastics using long-wavelength infrared hyperspectral imaging with imaging-type two-dimensional Fourier spectroscopy.

Despite recent progress in focal plane array Fourier transform infrared spectroscopy (FPA-FT-IR) for automatic microplastic (MP) discrimination, the analysis time is still too long (e.g., 9 h for a sample with a diameter of 47 mm) and the equipment is expensive. As a solution, a hyperspectral camera restricted to the near-infrared or short-wavelength infrared band could be applied. However, with these bands, the minimum discriminable size is only about 100 µm, and discrimination among darkly colored plastics is difficult. The long-wavelength infrared (LWIR) band is reportedly effective for discrimination among darkly colored plastics. In this study, we constructed a palm-sized LWIR hyperspectral camera (105 mm × 90 mm × 50 mm, 1.25 kg) for imaging-type two-dimensional Fourier spectroscopy. Our system used a general-purpose, inexpensive, and compact microbolometer for the LWIR band. This system could record the absorbance of black MPs (polystyrene, polyethylene, and polypropylene) in a 3.8 mm × 3.0 mm area in 36 s, which was less than 1/6th of the time required for FPA-FT-IR. Additionally, our system could obtain spectra for a 12 µm × 12 µm area. Because our device is cheaper and more compact than a FPA-FT-IR, it will be easier to take out in the field or on a research vessel.

Parametric standing wave generation of a shallow reflection plane in a nonrigid sample for use in a noninvasive blood glucose monitor.

When monitoring a moist sample using mid-infrared spectroscopy, its thickness must be <100 µm to avoid light absorption from the water. Therefore, we propose an ultrasonic-assisted mid-infrared spectroscopic imaging method that can generate a reflection plane at a depth of 100 µm from the surface of the sample by creating an ultrasonic standing wave. A frequency of 10 MHz is required to obtain an optical path length of 100 µm in biological samples. However, because biological samples generally have high compressibility, attenuation of ultrasonic waves at this frequency is significant. We use agar as a biological phantom and observe that a reflection plane is generated inside by ultrasonic standing waves using optical coherence tomography. It is found that when the sample is vibrated with an 800-kHz ultrasonic wave, a reflection plane is generated at a depth shallower than the theoretically predicted value. We believe that the reflection plane is generated by parametric standing waves, which are based on parametric effect. We detect the waveform distortion using an acoustic emission sensor and confirm the higher harmonics that generate the observed reflection plane using a fast Fourier transform.

Ultrasonic standing wave preparation of a liquid cell for glucose measurements in urine by midinfrared spectroscopy and potential application to smart toilets.

Smart toilets could be used to monitor different components of urine in daily life for early detection of lifestyle-related diseases and prompt provision of treatment. For analysis of biological samples such as urine by midinfrared spectroscopy, thin-film samples like liquid cells are needed because of the strong absorption of midinfrared light by water. Conventional liquid cells or fixed cells are prepared based on the liquid membrane method and solution technique, but these are not quantitative and are difficult to set up and clean. We generated an ultrasonic standing wave reflection plane in a sample and produced an ultrasonic liquid cell. In this cell, the thickness of the optical path length was adjustable, as in the conventional method. The reflection plane could be generated at an arbitrary depth and internal reflected light could be detected by changing the frequency of the ultrasonic wave. We could generate refractive index boundaries using the density difference created by the ultrasonic standing wave. Creation of the reflection plane in the sample was confirmed by optical coherence tomography. Using the proposed method and midinfrared spectroscopy, we discriminated between normal urine samples spiked with glucose at different concentrations and obtained a high correlation coefficient.

Wide-field mid-infrared hyperspectral imaging of adhesives using a bolometer camera.

By combining a bolometer detector with an imaging-type interferometer, an inexpensive, easy-to-handle wide-field mid-infrared hyperspectral imaging apparatus was produced. We measured the distributions of four types of thin adhesive layers on an aluminium plate and analysed the results using correlation coefficients to visualise the distribution of various adhesives that cannot be discerned by the naked eye or conventional methods such as visible/near-infrared spectroscopic/fluorescent photography. The measurement wavelength range, obtained spectrum's wavenumber resolution, and measurement time was 8-14 µm, about 9 cm-1, and about 30 s, respectively. Using conventional methods, adhesives could not be distinguished from the others. By using this method, we found that adhesives could be precisely distinguished by setting an appropriate threshold value for the correlation coefficient. Thus, our approach can accurately measure the spatial distribution of different types of adhesive that cannot be discriminated by conventional methods.

Use of protein array to investigate receptor tyrosine kinases activated in gastric cancer.

Our study used protein array technology to analyze the expression status of various activated receptor tyrosine kinases (RTKs) in gastric carcinoma; then, we sought to discover an effective therapeutic receptor tyrosine kinase for this disease and investigated the anti-tumor mechanism of the therapeutic RTK. In addition to the expressions of activated RTKs in human gastric cancer and adjacent normal mucosa, the expression of activated RTKs in gastric cancer cell lines, MKN74, MKN45, MKN7 and MKN1, were also studied. The RTKs activated in gastric cancer tissue are EGFR, ErbB2, FGFR1, FGFR2alpha insulin R, and EphA4. Among the RTKs activated in gastric cancer tissues, EGFR and ErbB2 were also activated in all gastric cell lines examined in this study. A subsequent in vitro experiment using subcutaneous gastric cancer-bearing athymic nude mice demonstrated that the ErbB2-targeting drug trastuzumab markedly suppressed the growth of gastric cancer. Moreover, using an angiogenesis protein array, the expressions of Ang I, FGF-alpha, FGF-beta TGF-beta and IL-8 in MKN74 xenograft tumors were found to be significantly reduced by treatment with trastuzumab, indicating that trastuzumab may inhibit the expression of angiogenic molecules in MKN74 cells in vivo. These data suggest that ErbB2 is activated in gastric cancer, and the ErbB2-targeting drug trastuzumab may be related to the reduction of Ang 1, FGFalpha, FGFbeta, TGFalpha and IL-8.