Hsin-Yi Tsai

The evaluation of blood flow velocity and heart rate by the frequency of oxygen saturation fluctuation in skin tissue

The oxygen in human body is transported by the hemoglobin and blood, and blood flow velocity (BFV) was related to the heart rate (HR); therefore, the oxygen saturation image of human skin can be used to evaluate the HR and BFV of human. When irradiating two different wavelengths light alternately and repeatedly, the frequency of oxygen saturation (SpO2) fluctuation (fc) can be obtained from the Fourier transformation of SpO2 images, and roughly applied to build the relationship between BFV and HR. In the experiment, a high speed light controller was employed to switch two LED light source (red-660 nm and NIR-890 nm). Due to the penetration depth of incident light increases with increasing wavelength, and the deoxy-hemoglobin (Hb) and oxy-hemoglobin (HbO2) has a relatively high absorptivity in visible and near-infrared (NIR) spectrum, respectively; the intensity of diffuse reflected images of skin can be used to compute the oxygen saturation images of skin tissue. The experiments show the SpO2 after 3 minutes exercise would decrease 3 % and recover in 100 seconds, and the SpO2 after 30 minutes exercise increased 1.5 % and became stable in 3 minutes. Simultaneously, the HR and BFV have the linear relationship to the frequency of SpO2 fluctuation (fc), so both two physiological indexes can be directly evaluated by SpO2 images.

Micro droplet generated by dual-differential piezoelectric ejection for powder-based 3D printer

The surgery time can be reduced by allografting from bone-substitute material or donors while compared to the autograft from patients own bone. The bone-substitute reconstructed by powder-based 3D printer has high compatibility with human tissue, so it is gradually applied to bone reconstruction in clinical research. In order to construct the proper bone-substitute from the porosity surface of powder and to keep good strength, the profile of ejection droplet is significantly. In the study, we proposed the dual-differential piezoelectric (DDP) technology to obtain the best micro droplet, and discussed the relationship between the operating parameters, droplet dimension and printing gap. In the experiment, the DDP putter was employed to generate the micro droplet, and the high speed camera was used to acquire the droplet images for analysis of droplet dimension. The results show the better operating voltage ranged from 4 to 5 V, and the smallest droplet dimension can be obtained while the triggered frequency of DDP putters decreased; especially from 200 to 100 Hz without phase shift. Besides, the printing gap is about 1 mm in printing process. In future, the results can improve the development of power-based 3D printing system, and the reconstruction bone with advantage of high strength can be printed and actually adopted into the patients body as the substitute tissue in clinical application.

The field of view and resolution of marco images enhanced by modified superresolution method

The properties of the image acquired from a general camera contain a large field of view (FOV) and low resolution. In contrast, the microscopy usually offers higher magnification image a smaller FOV but high resolution. This study attempts to develop a modified super resolution (MSR) method to obtain both of high resolution and large FOV properties for criminal identified microscopic images. The MSR method can analysis the images pixels either from the intensity of single point (ISP) or the intensity of neighbor point (INP), when a microscopic image (150X) captured under white light, and three macro images (60X) captured under three different wavelength lights (red-620nm, green-520nm and blue-460nm), and then can reconstruct a new criminal identified image with high resolution and large FOV. Finally the simulated experiments in an ant model show that, the ISP analysis offers a reconstructed image with higher contrast and identification degree, synchronously the INP analysis affords an image has smoother edge.