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Portable LED-induced autofluorescence imager with a probe of L shape for oral cancer diagnosis
(2015-01-01)
Huang, Ting-Wei
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Lee, Yu-Cheng
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Cheng, Nai-Lun
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Yan, Yung-Jhe
;
Chiang, Hou-Chi
The difference of spectral distribution between lesions of epithelial cells and normal cells after excited fluorescence is one of methods for the cancer diagnosis. In our previous work, we developed a portable LED Induced autofluorescence (LIAF) imager contained the multiple wavelength of LED excitation light and multiple filters to capture ex-vivo oral tissue autofluorescence images. Our portable system for detection of oral cancer has a probe in front of the lens for fixing the object distance. The shape of the probe is cone, and it is not convenient for doctor to capture the oral image under an appropriate view angle in front of the probe. Therefore, a probe of L shape containing a mirror is proposed for doctors to capture the images with the right angles, and the subjects do not need to open their mouse constrainedly. Besides, a glass plate is placed in probe to prevent the liquid entering in the body, but the light reflected from the glass plate directly causes the light spots inside the images. We set the glass plate in front of LED to avoiding the light spots. When the distance between the glasses plate and the LED model plane is less than the critical value, then we can prevent the light spots caused from the glasses plate. The experiments show that the image captured with the new probe that the glasses plate placed in the back-end of the probe has no light spots inside the image.
LED Induced Autofluorescence (LIAF) Imager with eight multi-filters for Oral Cancer Diagnosis
(2016-01-01)
Huang, Ting-Wei
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Cheng, Nai-Lun
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Tsai, Ming-Hsui
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Chiou, Jin-Chern
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Mang, Ou-Yang
Oral cancer is one of the serious and growing problem in many developing and developed countries. The simple oral visual screening by clinician can reduce 37,000 oral cancer deaths annually worldwide. However, the conventional oral examination with the visual inspection and the palpation of oral lesions is not an objective and reliable approach for oral cancer diagnosis, and it may cause the delayed hospital treatment for the patients of oral cancer or leads to the oral cancer out of control in the late stage. Therefore, a device for oral cancer detection are developed for early diagnosis and treatment. A portable LED Induced autofluorescence (LIAF) imager is developed by our group. It contained the multiple wavelength of LED excitation light and the rotary filter ring of eight channels to capture ex-vivo oral tissue autofluorescence images. The advantages of LIAF imager compared to other devices for oral cancer diagnosis are that LIAF imager has a probe of L shape for fixing the object distance, protecting the effect of ambient light, and observing the blind spot in the deep port between the gumsgingiva and the lining of the mouth. Besides, the multiple excitation of LED light source can induce multiple autofluorescence, and LIAF imager with the rotary filter ring of eight channels can detect the spectral images of multiple narrow bands. The prototype of a portable LIAF imager is applied in the clinical trials for some cases in Taiwan, and the images of the clinical trial with the specific excitation show the significant differences between normal tissue and oral tissue under these cases.
Tunable fiber confocal sensor with LED
(2015-01-01)
Weng, Chun-Jen
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Lan, Tzu-Hsien
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Hwang, Chi-Hung
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Chu, Nien-Nan
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Huang, Chien-Yao
A novel concept of confocal sensor based on focal lens is proposed to measure the displacement. The light source is a stabilized fiber coupled LED. A 1x2 graded-index multimode fiber optic coupler is used in this sensor. One port is a LED input port via SMA connector, another port is a LED output port connected to a reflective collimator and the other port is a reflective sensor port connected to a photo detector. The focusing sensor head is the cascade of a focal lens and a 20X objective lens. In this confocal displacement sensor, LED passes through a focal lens and an objective lens so that the LED beam focuses at a fixed focal point. A test target is placed after the objective lens. The displacement between the sensor head and a target can be measured quickly by detecting the reflective power according to the confocal principle. The long-term stability of LED is under 0.5%. The effective back focal length is varied from 5.67mm to 6.57mm by 0-290mA current driving so that the measuring range is about 0.9mm. The FWHM resolution of displacement is about 50 mu m. This sensor has the features of low cost, high stability, high precision and compact.
Portable LED-induced autofluorescence spectroscopy for oral cancer diagnosis
(2017-04-01)
Yan, Yung-Jhe
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Huang, Ting-Wei
;
Cheng, Nai-Lun
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Hsieh, Yao-Fang
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Tsai, Ming-Hsui
Oral cancer is a serious and growing problem in many developing and developed countries. To improve the cancer screening procedure, we developed a portable light-emitting-diode (LED)-induced autofluorescence (LIAF) imager that contains two wavelength LED excitation light sources and multiple filters to capture ex vivo oral tissue autofluorescence images. Compared with conventional means of oral cancer diagnosis, the LIAF imager is a handier, faster, and more highly reliable solution. The compact design with a tiny probe allows clinicians to easily observe autofluorescence images of hidden areas located in concave deep oral cavities. The ex vivo trials conducted in Taiwan present the design and prototype of the portable LIAF imager used for analyzing 31 patients with 221 measurement points. Using the normalized factor of normal tissues under the excitation source with 365 nm of the central wavelength and without the bandpass filter, the results revealed that the sensitivity was larger than 84%, the specificity was not smaller than over 76%, the accuracy was about 80%, and the area under curve of the receiver operating characteristic (ROC) was achieved at about 87%, respectively. The fact shows the LIAF spectroscopy has the possibilities of ex vivo diagnosis and noninvasive examinations for oral cancer. (C) 2017 Society of Photo-Optical Instrumentation Engineers (SPIE)
An experimental study on the heat dissipation of LED lighting module using metal/carbon foam
(2013-11-01)
Yang, Kai-Shing
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Chung, Chi-Hung
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Lee, Ming-Tsang
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Chiang, Song-Bor
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Wong, Cheng-Chou
In this study, thermal performance of the cooling modules applicable for Par 38 light bulb is investigated. A total of six heat sink modules, including the basic reference design, metal foam, and carbon foam are tested and compared. Tests are performed and analyzed using the transient test method based on JESD51-1 standard. It is found that the thermal resistance from junction to die attach is quite small. By contrast, the thermal resistance of the heat sink dominates the total resistance, and it comprises 55% of the total resistance for the standard heat sink module. With some slight opening on the base plate, the thermal resistance can be improved by approximately 12%. The thermal resistance for the carbon foam having an embedded metal plate shows the least thermal resistance of 1.14 K/W, followed by the carbon foam, and then the metal foam. The lower thermal resistance of carbon foam in association with copper metal foam is due to its higher emissivity. In addition to better heat transfer performance as compared to the standard plate heat sink, the utilization of carbon foam and metal foam can also significantly reduce the weight of the heat sink. In this study, the weight of the heat sink can be reduced as much as 33%. (C) 2013 Elsevier Ltd. All rights reserved.
Simple digital FIR equalizer design for improving the phosphor LED modulation bandwidth in visible light communication
(2013-08-01)
Yeh, C. H.
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Chow, C. W.
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Liu, Y. F.
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Huang, P. Y.
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光電工程學系
We propose and demonstrate a simple digital post-equalization technique to improve the bandwidth-limitation of light-emitting-diode (LED) visible-light-communication (VLC) channel. The design of finite-impulse-response equalizer according to the channel response is presented to improve the bandwidth limitation of LED VLC channel. Here, no optical blue filter is used. The simulation and experimental results show 10 times enhancement of the direct modulation speed of white-light LED VLC system. When compares with the previous demonstration using high-pass equalization circuit constructed by lumped capacitor and resistor, the proposed scheme shows an improvement in signal quality and transmission distance, and a 10 Mbit/s error-free free-space transmission over 1 m can be achieved under the bit error rate of .
Enhanced cooling for LED lighting using ionic wind
(2013-01-15)
Chen, Ing Youn
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Guo, Mei-Zuo
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Yang, Kai-Shing
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Wang, Chi-Chuan
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機械工程學系
This study employs ionic wind to augment heat transfer of a LED mounted on a substrate. The size of the LED chip is 0.9 mm x 0.9 mm with a nominal power of 1 W. A needle type electrode is used to generate ionic wind with the applied voltage ranging from 4 to 11 kV. The effects of aligned angle, electrode polarity, separation distance, and ground configuration on the thermal resistance of the LED substrate are examined in this study. For the same applied voltage, it appears that the thermal resistance for the negative polarity is lower than that for the positive one and the negative electrode also has a wilder operation range. The thermal resistance can be reduced as much as 50% in the test range. The thermal resistance is slightly reduced when the aligned angle is increased from 0 degrees to 20 degrees, but a further increase of aligned angle casts no further reduction on the thermal resistance. It is found that the influence of vertical separation distance between the needle and ground electrode is moderately higher than that of horizontal separation distance. Test results also indicate that the mesh ground electrode shows moderately lower thermal resistance than those of point or line electrode. (C) 2012 Elsevier Ltd. All rights reserved.
Thermal characterization of shrouded plate fin array on an LED backlight panel
(2011-10-01)
Shyu, Jin-Cherng
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Hsu, Keng-Wei
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Yang, Kai-Shing
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Wang, Chi-Chuan
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機械工程學系
This study experimentally investigates a 348 mm x 558 mm LED backlight panel consisting of 270 1-W LEDs and a plate-fin heat sink in an acrylic housing. Effects of shroud clearance, obstructions at entrance or exit on the overall performance are also examined. The results show that the heat transfer coefficient is very slightly reduced with the rise of shroud clearance from 0 mm to 5 mm, followed by a notable rise but it peaks at a shroud clearance between 10 and 20 mm. A further increase of shroud clearance leads a marginal decrease of heat transfer coefficient. It is found that the maximum temperatures within the LED panel are not necessarily located at the center region due to the edge effect. On the other hand, the temperature variation along the longitudinal direction indicates a local minimum Nusselt number occurring near the exit of LED panel. This unique phenomenon is associated with the development of velocity and temperature field, and is consistent with previous numerical examinations. On the other hand, the obstruction placed at the exit are often severe than at the entrance. (C) 2011 Elsevier Ltd. All rights reserved.
Automated SMD LED inspection using machine vision
(2011-12-01)
Perng, Der-Baau
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Liu, Hsiao-Wei
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Chang, Ching-Ching
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工業工程與管理學系
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Department of Industrial Engineering and Management
Light-emitting diodes (LED) are used in many different applications. However, some LED defects are unavoidable in large-volume fabrication and taping processes. These defects may include missing components, incorrect orientations, inverse polarity, mouse bites, missing gold wires, and surface stains. Human visual inspection has traditionally been used in LED-packaging factories. However, it is subjective, time consuming, and lacking consistent inspection results. This paper proposes a machine vision system combining an automatic system-generated inspection regions (IR) method to inspect two types of LED surface-mounted devices (SMDs). Experimentation revealed that the proposed automatic inspection method could successfully detect defects with up to 95% accuracy for both types (Types 1 and 2) of SMD LEDs. The online inspecting speed was on average under 0.3 s per image.
Polyfluorene containing diphenylquinoline pendants and their applications in organic light emitting diodes
(2005-02-15)
Su, HJ
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Wu, FI
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Shu, CF
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Tung, YL
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Yun, C
We present a short, efficient synthetic route for the preparation of a novel polyfluorene copolymer (PF-Q) containing two electron-deficient, 2,4-diphenylquinoline groups functionalized at the C-9 positions of alternate fluorene units that form a three-dimensional cardostructure. The presence of the rigid bulky pendent groups leads to a polyfluorene possessing a high glass-transition temperature (207 degreesC) and very good thermal stability (5% weight loss observed at 460 degreesC). A photoluminescence study revealed that the Forster energy transfer from the excited quinoline groups to the polyfluorene backbone is Very efficient; it also demonstrated that, the commonly observed aggregate/excimer formation in polyfluorenes is suppressed very effectively, in this polymer, even after it has been annealed at 150 degreesC for 20 h. A light emitting diode (LED) device prepared with PF-Q as the emitting layer exhibits a stable blue emission with a maximum brightness of 1121 cd/m(2) at 12 V and a maximum external quantum efficiency of 0.80% at 250 cd/m(2). We also used PF-Q, which contains diphenylquinoline units that behave as electron-transporting side chains, as a host. material and doped it with 2.4 wt % of a red-emitting phosphorescent dye, Os(fppz). to realize a red electrolumineseence with CIE color coordinates of (0.66, 0.34). The doped device exhibits a maximum external quantum efficiency of 6.63% (corresponding a luminance efficiency of 8.71 cd/A) at a current density of 47.8 mV/cm(2) together with a maximum brightness of 10457 cd/m(2). (C) 2005 Wiley Periodicals, Inc.

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