For blood glucose level measurement of dialysis machines, we proposed AAA-battery-size ATR (Attenuated total reflection) Fourier spectroscopy in middle infrared light region. The proposed one-shot Fourier spectroscopic imaging is a near-common path and spatial phase-shift interferometer with high time resolution. Because numerous number of spectral data that is 60 (= camera frame rare e.g. 60[Hz]) multiplied by pixel number could be obtained in 1[sec.], statistical-averaging improvement realize high-accurate spectral measurement. We evaluated the quantitative accuracy of our proposed method for measuring glucose concentration in near-infrared light region with liquid cells. We confirmed that absorbance at 1600[nm] had high correlations with glucose concentrations (correlation coefficient: 0.92). But to measure whole-blood, complex light phenomenon caused from red blood cells, that is scattering and multiple reflection or so, deteriorate spectral data. Thus, we also proposed the ultrasound-assisted spectroscopic imaging that traps particles at standing-wave node. Thus, if ATR prism is oscillated mechanically, anti-node area is generated around evanescent light field on prism surface. By elimination complex light phenomenon of red blood cells, glucose concentration in whole-blood will be quantify with high accuracy. In this report, we successfully trapped red blood cells in normal saline solution with ultrasonic standing wave (frequency: 2[MHz]).
We propose the extremely-compact-size line-imaging Fourier spectroscopy for smartphones. We realize the near
common-path interferometer with strong robustness for mechanical vibrations by installing the transmission-type
relative-inclined phase-shifter. The interferogram of an imaging line is formed as 2-dimensional fringe pattern on
imaging sensor, such as CCD camera. In other words, the horizontal axis on an imaging sensor is assigned to phase-shift
value. And the vertical axis is corresponds to image formation coordinate. Thus, by installing a relatively-inclined thin glass
into imaging optics, such as smartphone, we will realize the line-imaging Fourier spectroscopy for healthcare
sensor in daily-life environments.
The purpose of this study is to correct baseline shift in absorbance spectrums caused by light source fluctuation.
To improve quantitative evaluation performance of blood glucose level, baseline shift is corrected by multiple
scatter correction (MSC). Moreover, to increase the effect of the MSC, water vapor absorbance is subtracted, and
relative glucose absorbance are calculated by dividing with hemoglobin absorbance at 1544 [cm-1]. In order to
verify the effectiveness of the proposed spectrum correction method, light source fluctuation is simulated on the
Fourier transform infrared spectroscopy (FT-IR), and we apply the proposed method to the spectrums measured
by FT-IR. From the simulation results, the baseline shift was successfully reduced by proposed method.
In daily-life environment, the quantitative measurement of biological substances, such as the blood glucose level in the human skin, is strongly required to realize the non-invasive healthcare apparatus. Fourier-spectroscopic-tomography of the little-finger-size with high time-resolution and with the strong robustness for mechanical vibrations is proposed. The proposed method is a kind of near-common-path interferometer with spatial phase-shift method. We install the transmission-type relative-inclined phase-shifter on the optical Fourier transform plane of the infinity corrected optical system. The phase shifter is constructed with the cuboid and wedge prisms to give the relative phase-shift spatially between each half-flux of the objective beams. The interferograms from each single-bright-point on an objective surface in a line are formed as fringe patterns on 2-dimensional imaging array devices. And because the proposed method is based on the imaging optics, only emitted rays from a focal plane can contribute forming of interferograms. Thus, the measurement plane can be limited onto the focal plane only. From the spectroscopic tomography, only at a localized vessel area in human skins, we can get the pinpointed near-infrared spectroscopic data. And we can expect the improvement of the determination precision, because a Fourier spectroscopic-character is acquired from multiple intensity data in accordance with amount of phase-shift. From the statistical point of view, the gradation of detector is improved with the square root of sample number, based on t-distribution. We constructed the statistical model to assure the determination accuracy, and demonstrated the feasibility of the glucose sensor using liquid cells.