In the last two decades, microfluidic technologies have shown the great potential in developing portable and point-of care testing blood cell analysis devices. It is challenging to integrate all free-space detecting components in a single microfluidic platform. In this paper, a microfluidic cytometer with integrated on-chip optical components was demonstrated. To facilitate on-chip detection, the device integrated optical fibers and on-chip microlens with microfluidic channels on one polydimethylsiloxane layer by standard soft photolithography. This compact design increased the sensitivity of the device and also eliminated time-consuming free-space optical alignments. Polystyrene particles, together with red blood cells and platelets, were measured in the microfluidic cytometer by small angle forward scatter. Experimental results indicated that the performance of the microfluidic device was comparable to a conventional cytometer. And it was also demonstrated its ability to detect on-chip optical signals in a highly compact, simple, truly portable and low cost format which was perfect suitable for point-of-care testing clinical hematology diagnostics.
Planning of irradiance distribution (PID) is one of the foremost factors for on-demand treatment of port wine stains (PWS) with photodynamic therapy (PDT). A weighted optimization method for PID was proposed according to the grading of PWS with a three dimensional digital illumination instrument. Firstly, the point clouds of lesions were filtered to remove the error or redundant points, the triangulation was carried out and the lesion was divided into small triangular patches. Secondly, the parameters such as area, normal vector and orthocenter for optimization of each triangular patch were calculated, and the weighted coefficients were determined by the erythema indexes and areas of patches. Then, the optimization initial point was calculated based on the normal vectors and orthocenters to optimize the light direction. In the end, the irradiation can be optimized according to cosine values of irradiance angles and weighted coefficients. Comparing the irradiance distribution before and after optimization, the proposed weighted optimization method can make the irradiance distribution match better with the characteristics of lesions, and has the potential to improve the therapeutic efficacy.
The precision of manufacturing and installing together with the flexibility is a serious challenge for laser induced fluorescent detector (LIFD) of microfluidic chip. In this paper, a focus tunable liquid lens based on liquid zoom system for LIFD with automatic adjustment is proposed. With the help of liquid zoom lens whose surface curvature can be varied continuously by current, the system can achieve a continuous zoom. Instead of using the traditional mechanical axial displacement scanning motion mechanism, the proposed zoom system can implement axial displacement scan by means of the well-designed autofocus feedback current control function. The simulation results show that the focal length variation range of the designed optical system is 4.87mm～ 8.40mm, which is also the axial scanning displacement range. The size of scanning spot is around 15μm when a 473nm wavelength laser is used, which can meet the demand of microfluidic chip detection. With this design, the required precision of the LIFD could be reduced significantly as well as costs. Moreover, it also makes the detection of microfluidic chip qualified to adapt to different size of detecting channel.
Controllable and effective irradiation of lesions is among the key factors that affect the potency of photodynamic therapy (PDT). An optimization method for the irradiance distribution of treatment was proposed which can be used to improve the efficacy of PDT and allow more lesions to receive the desired irradiance level in a single therapy session. With the proposed digital illumination binocular treatment system, the preferred surface normal vectors, irradiation angles, as well as area and weight coefficients of lesions can be achieved and used as characteristic parameters to optimize the irradiation direction. Two port-wine stain phantom experiments were performed. The comparison of the illumination area between preoptimization and postoptimization showed that the proposed method can effectively guide the light source control, improve the distribution of light dose, and increase the effective treatment area.
Photodynamic Therapy is regarded as the best treatment for port wine stains, which has the main adverse effect of various degrees of pain (mild to moderate) during the illumination. Though the cooling and cold water have been used to reduce such pain, there is still no scientific evidence for these relief. In this paper, a realistic skin model is built to simulate the distribution of light under treatment, which helps control the light dose and temperature, and improve the clinical results. Comparing with the general parallel skin model, a curving stratum basale layer is used in this paper, and various blood vessel configurations such as single and multiple vessels with horizontally and vertically oriented, curve vessels, various vessel diameter and various radius of curvature of stratum basale layer are simulated. The results shows a more realistic modeling for the thermal damage and help to relief the pain in the treatment.
Photodynamic therapy (PDT) is one of the best available treatment for dermatology, especially for port wine stains (PWS), in which the efficacy is associated with the light dose, the photosensitizer concentration, the oxygen concentration and so on. Accurate control of the light dose will help doctors develop more effective treatment protocols, and reduce the treatment cost. Considering the characters of PWS, a binocular vision system composed of a camera, a digital projector and a computing unit is designed. An accurate 3D modeling of patients was achieved using a gray coding structured light, and then the lesions were segmented based on HSV space. Subsequently, each 3D point is fit on the surface by a nearest neighbor algorithm and the surface normal can be obtained. Three dimensional localization of lesion provide digital objective basis for automatic control of light device. The irradiance on the surface at a given angle can be assessed, and the optimum angle for the treatment can be solved and optimized by the doctor to improve irradiation areas.
Venipuncture is the most common way of all invasive medical procedures. A vein display system can make vein access
easier by capturing the vein information and projecting a visible vein image onto the skin, which is correctly aligned with
the subject’s vein. The existing systems achieve correct alignment by the design of coaxial structure. Such a structure
causes complex optical and mechanical design and big physical dimensions inevitably. In this paper, we design a stereovision-
based vein display system, which consists of a pair of cameras, a DLP projector and a near-infrared light source.
We recover the three-dimensional venous structure from image pair acquired from two near-infrared cameras. Then the
vein image from the viewpoint of projector is generated from the three-dimensional venous structure and projected
exactly onto skin by the DLP projector. Since the stereo cameras get the depth information of vessels, the system can
make sure the alignment of projected veins and the real veins without a coaxial structure. The experiment results prove
that we propose a feasible solution for a portable and low-cost vein display device.
The optical signal on microfluidic chip is hard to be collected. To improve the excitation power and collection efficiency,
we introduced a simple, inexpensive fabrication method to increase the couple rate of optical fiber. This small element is
a polymer and air integrated microlens that can improve the optical signal detection. Compared to other established
protocols, this procedure allows a simple, miniaturizing and inexpensive microlens fabrication with high reproducibility.
The air microlens was produced by using direct lithograph of SU-8 resist to reduce the beam divergence of optical fiber.
Owing to its ability to achieve customized microlens for specific applications, this technique can be used in a variety of
applications, such as a blood cell counting system based on microfluidic chip.
3D reconstruction, an important point in computer vision, has a promising application potential in endoscopic-assisted
minimally invasive surgery. In this paper, a 3D reconstruction method based on image sequences is proposed, in which
the improved SIFT feature is applied for point extraction and matching, as well as an optical tracker is used to get the
orientation of the camera in real time. The proposed approach is evaluated on sequence digital images gotten from an
1394 camera and the experimental results show that the proposed approach is effective.
For the using of space lab, a miniaturized low-power light-emitting diode-induced fluorescence (LED-IF) detector
for capillary electrophoresis was constructed and evaluated. In this work, a more efficient exciting light source based on
Led was developed and a convenient detect plate was produced to release the problem of focusing LED light into a spot
with a diameter less than 100μm.besides these, all closed structure was used to avoid light cluster, and photomultiplier
tube was used to be detector.for the reason of power and flexible, the ultra-low Power MCU(MSP430F449) was used to
complete signal processing. The system exhibited the result in the concentration range of 1.0×10-6 to 1×10-7Mol/L.
Blob detection which focuses on detecting points or regions of a different intensity than the surrounding image is
increasingly used in consumer products such as human-computer interfaces and motion tracking. Because blob detection is
computationally intensive but requires relatively simple arithmetic operations, it is an ideal candidate for parallelization in
hardware. The main goal of this paper is to develop a hardware implementation for blob detection structure that is able to
detect multipoint in a video image on a Xilinx FPGA platform. This system consists of three functional blocks. The first
block use a dual port memory to get the histogram of video data and then to obtain the threshold value for the image frame.
The second block applies the threshold value to the video stream data, gets the line connected component, and these
components are then transferred into the third block by Fast Simplex Link (FSL). The third block is a Microblaze processor
which does the label connection and gets the center of points. This approach is implemented on a Xilinx Spartan3 chip with
640 by 480 resolutions up to 30Hz. It can be used in various low cost consumer applications.
We adopt double-plate sheering interferometers to perform an optical tweezers array system. In the optical tweezers
array system, the reflecting mirror is replaced by an optical scanner to be a beam translator. The optical scanner is driven
by an input signal to control the interference strips movement. However, if the interference strips move periodically, the
trapped particles would move along with the strips with the same regulation. So, the particles could not be separated
from the other particles. We use an external modulating device to be a shutter to control the laser beam. Then the trapped
particles would continue moving because of inertia during the laser beam is blocked, and be trapped again after the
shutter opens. If the moving speed of liquid is limited properly, the particles can be separated continuingly and collected.
At the end of this article, we illustrate the result of conducting the novel method and characteristics of the system.
In biological scientific research, separating biological macromolecules or cells in liquid is always a
challenging job. Optical tweezers have been a valuable research tool since their invention in the 1980s. One of the
most important developments in optical tweezers in recent years has been the creation of two-dimensional arrays of
optical traps. In this paper, a method based on interference is discussed to form the gradient laser fields, which may cause
spatial modulation of the concentration of particles. The parameters related with the optical tweezers array are discussed
in detail and simulated by Matlab software to show the impact factor of the important parameters for the concentration
distribution of the particles. The spatial redistribution of particles in a laser interference field could be also predicted
according the theoretical analysis.
Magnetic tracking system is widely used in a Virtual or Augmented Reality system to track the orientation and position of an object in space. When being applied in medical applications such as surgical navigation or medical image registration, accurate 6 DOF (Degree-of-Freedom) tracking is especially important. In order to compensate the influence of metal object and magnetic fields in the surrounding environments on the accuracy of the measurements, an AC magnetic tracking system whose orientation is obtained with the output of 3-axis orthogonal magnetic sensors and 2-axis accelerometers is designed. On the basis of analyzing the influence of environmental magnetic fields on the measurement accuracy of heading, a compensation algorithm is presented, which fits the outputs of the magnetic sensors to an ellipse with the principle of least square and rotation invariant and calibrates the heading with the parameters of the ellipse to rotate and scale the measurement results. Compared with the existing approach, the proposed method can effectively compensate the influence of environmental interference when the magnetic tracking system moves in horizontal plane and can also be applied in the applications with continuous movements. Experimental results show that the proposed method can effectively compensate environmental interference and improve the tracking accuracy.
Proc. SPIE. 5253, Fifth International Symposium on Instrumentation and Control Technology
KEYWORDS: Signal to noise ratio, Detection and tracking algorithms, Sensors, Error analysis, Interference (communication), Optoelectronics, Signal processing, Algorithm development, Signal detection, Automatic tracking
Many applications concerning the estimation of the parameters of the sinusoidal signal under the condition of ultra-low SNR (-30 to -60 dB) are realized with Phase Sensitive Detection (PSD). It is necessary for a traditional analogue PSD to have a reference signal that has the same frequency as the measured sinusoidal signal, but in many cases such a reference signal is difficult to obtain. An adaptive DPSD (digital phase sensitive detector) algorithm with the automatic tracking of the reference signal frequency is presented in this paper. The frequency response and the realization of the DPSD algorithm are studied. Simulation results coincide with the theoretical analysis. The proposed algorithm can be used to estimate the parameters of a sinusoidal signal under the condition of ultra-low SNR (-30 to -60 dB).
Electromagnetic tracking devices are often used to track location and orientation of a user's hand and/or head in a Virtual Reality system. However the tracking precision is not always high enough due to the dependence of the system on the local electromagnetic field that can be easily altered by ambient magnetic fields. A tracking system with pulsed AC (Alternative Current) magnetic field is presented based on the analysis of the principle and shortcomings of the DC (Direct Current) electromagnetic tracking system. The structure of the proposed system and the iterative digital correlator used for processing the received data are described. The simulation result shows the feasibility of the proposed system. Actual electromagnetic tracking system can be designed on the basis of the research.
A wide variety of techniques for manipulating 3D objects in VR (Virtual Reality) systems have been implemented recently. But the shortcomings of the present interaction devices limit the types of manipulation that the user can perform in the virtual world. In this paper an interaction device that enables the user to interact with the virtual environment with different gestures is presented. By measuring the joint angles of the individual fingers with fiber optic sensors and tracking the relative position and orientation of the palm with AC (Alternating Current) pulsed magnetic tracker, the proposed interaction device can track an enormous variety of gestures and give the VR system remarkably rich expressive power. The relationship between the output of the fiber optic sensor and the actual flexure angle is studied. A digital phase sensitive detector is constructed and an iteration algorithm is used to extract the amplitudes of the received signals of the magnetoresistive sensors. The algorithm to calculate the spherical coordinates from the output of the accelerometers and magnetoresistive sensors is deducted. The design of the proposed interaction device and the experiment result are also presented.