Xiaosu Yi

Research on the influence of membrane on the performance of vibration sensor

Intensity modulated fiber optic sensor is one of the fastest growing and most widely used fiber optic sensors. A double optical-fiber vibration sensing system with a new kind of membrane is introduced in this article. The system is based on optical intensity modulation and is characterized by the membrane that is used to sense vibration. The mechanism of film sensing is described and the model showing the relationship between film parameters (reflection coefficient and radius of curvature) and the sensor performance is established. With the simulated responses, a membrane structure with high sensitivity is developed. The experimental setup used to test the performance of the sensor is presented. The sensor can detect the minimum vibration amplitude of 0.02μm. The frequency response is from 300Hzto1.8kHz.

Chapter 2 – Acoustic, Electromagnetic and Optical Sensing and Monitoring Methods

Abstract Due to capabilities of transmission in underground, a brief introduction on underground measurement methods by adopting kinds of “wave” (including field wave, acoustic wave, and electromagnetic wave) is presented. Among them, acoustical measurement methods are the most widely used in practical applications. Hence, some typical acoustical measurement methods are introduced with more details, from their principles to application examples. Electrical and electromagnetic methods are also widely adopted and more traditional methods in geological exploration and subsurface structure detection are described. Several routine approaches and their applications are exhibited, too. While, in practical applications, how to sense the “waves” in rugged measurement environment is another important issue. Due to the presence of many extra benefits in “waves” sensing compared to traditional methods, optical sensing techniques are summarized and introduced with their application examples. Ground penetrating radar (GPR) is a nondestructive evaluation (NDE) technology for detecting, locating, and inspecting objects or structures buried underneath ground surface. It is also applicable to detect objects behind walls or other dielectric barriers. In this chapter, the operating mechanism of GPR is explained. Moreover, the GPR circuit design, signal processing, and applications are presented.

Unlabeled flow cellular deformation measurement based on digital holographic microscopy

Living cells as phase objects require not only non-invasive measurement but also quantitative phase information during dynamic biopsy. Digital Holographic Microscopy (DHM), measuring three-dimensional morphology without changing the active condition of cells and in situ inspection, is becoming excellent tools for biology research. We have described a DHM method for quantitative, unlabeled observation of living cell subjected to fluid shear stress (FSS) in flowing fluid. The holographic recording system combined with the fluid shear system is improved. The numerical reconstruction technique firstly employed deep learning Convolutional Neural Network model filter, which achieved automatically processing large scale the spectrum of holograms immediately. Osteocytes as the experimental samples were observed and their morphological changes under the stimulation of FSS was successfully measured.

High-accuracy three-dimensional tomographic observation of cell clusters

Digital holographic micro-tomography (DHMT) is widely used for three-dimensional (3-D) detections in biomedical research, from which the information of refractive indexes (RI) distributions of cells obtained can reflect some pathological states. When measuring cells, a capillary is usually used to contain and rotate them. The accuracy of diffraction tomography methods, which is commonly used, is likely to decrease when the object induces complex scattering effects, especially when measuring cell clusters. The nonlinear algorithm based on multi-slice wave propagation method (WPM) we proposed earlier is preferred in these situations. In this paper, we perform 3-D measurements of cell clusters using the setup-rotating system and the WPM-based nonlinear algorithm. Quantitative 3-D distributions of RI can be obtained accurately to display the structures of the cell clusters. The experimental results demonstrate that the WPM-based nonlinear algorithm can provide high accuracy for cell clusters.