Da-Sheng Lee

DNA detection using commercial mobile phones

This study investigates the feasibility of using mobile phones cameras for DNA detection. DNA amplification uses the convective polymerase chain reaction (cPCR) technique due to its simple mechanism, which requires no thermal cycling control. Fluorescence increment analysis and information entropy analysis are employed separately to determine whether the test samples contain target DNA (Positive) or not (Negative). The fluorescence increment method uses the brightness of the captured images before and after DNA amplification to calculate ΔF. ΔF values above a threshold level indicate that the test sample is positive. The information entropy method defines the probability, P(C/X), which indicates whether the fluorescence image tends towards a specific shape. If a DNA template is successfully amplified, the captured fluorescence image should be a perfect circle. P(C/X) provides a threshold of 0.5 to identify a circle and values above 0.5 indicate the test sample is positive. Experimental results show that P(C/X) is more effective than ΔF for determining DNA detection results. The information entropy analysis method is applied to ten mobile phones of three different brands equipped with camera sensors, which have pixel numbers ranging from 120 M to 800 M. The clinical evaluation study (n = 60) for screening hepatitis B virus (HBV) plasmid samples shows that the accuracy rate of all models of mobile phones ranges from 85% to 100%. This illustrates that successful DNA detection can be achieved using the most widely deployed electronic device.

Applications of Ferro-Nanofluid on a Micro-Transformer

An on-chip transformer with a ferrofluid magnetic core has been developed and tested. The transformer consists of solenoid-type coil and a magnetic core of ferrofluid, with the former fabricated by MEMS technology and the latter by a chemical co-precipitation method. The performance of the MEMS transformer with a ferrofluid magnetic core was measured and simulated with frequencies ranging from 100 kHz to 100 MHz. Experimental results reveal that the presence of the ferrofluid increases the inductance of coils and the coupling coefficient of transformer; however, it also increases the resistance owing to the lag between the external magnetic field and the magnetization of the material.

The evolution of real-time PCR machines to real-time PCR chips

Development of Micro-Electro-Mechanical Systems (MEMS) technology has recently allowed the migration of real-time polymerase chain reaction (PCR) machines to lab-on-a-chip systems. The miniaturization of biological instruments has been studied extensively, with several prototypes constructed and tested. In this study, the lab-on-a-chip system is evaluated; its DNA quantification is estimated by theorems, and the specifications of proposed chip prototypes are compared with the original machines. The analysis results suggest five hypotheses. Using experiments and the data collected from published papers, these hypotheses were either verified or rejected, and the advantages and shortcomings of real-time PCR chips were identified. The proven advantages of the lab-on-a-chip system are its compact size, low sample volume to nano-liter, and short analysis time-less than 10s to complete one PCR cycle and 370 s for completing the whole quantification process. However, the detection limits, quantification uncertainties, and melting analysis ability of the chip prototypes are at best comparable to, and perhaps worse than, those of commercial instruments. Real-time PCR chips are not perfectly accurate diagnostic tools for a laboratory but they have advantages over traditional techniques for point-of-care testing.

Disk-shaped miniature heat pipe (DMHP) with radiating micro grooves for a TO can laser diode package

A mounting base integrated with disk-shaped miniature heat pipe (DMHP) is designed for laser diode TO can package in the present study. The heat spreading performance of the disk-shaped miniature heat pipe is also presented. The present mounting base is made of aluminum (6061 T6) other than the conventional TO can package with oxygen free copper. The mounting base shows different thermal resistance with different working fluid charge volume. By optimizing the working fluid charge volume, the thermal resistance of the present mounting base will become lower than the conventional base with an oxygen free copper disk for TO can package. Moreover, this novel design can be manufactured on a massive scale and the fabrication cost can thus be effectively reduced.

Investigation of electrical and magnetic properties of ferro-nanofluid on transformers

This study investigated a simple model of transformers that have liquid magnetic cores with different concentrations of ferro-nanofluids. The simple model was built on a capillary by enamel-insulated wires and with ferro-nanofluid loaded in the capillary. The ferro-nanofluid was fabricated by a chemical co-precipitation method. The performances of the transformers with either air core or ferro-nanofluid at different concentrations of nanoparticles of 0.25, 0.5, 0.75, and 1 M were measured and simulated at frequencies ranging from 100 kHz to 100 MHz. The experimental results indicated that the inductance and coupling coefficient of coils grew with the increment of the ferro-nanofluid concentration. The presence of ferro-nanofluid increased resistance, yielding to the decrement of the quality factor, owing to the phase lag between the external magnetic field and the magnetization of the material.

A real-time convective PCR machine in a capillary tube instrumented with a CCD-based fluorometer

Abstract This research reports the design, analysis, integration, and test of a prototype of a real-time convective polymerase chain reaction (RT-cPCR) machine that uses a color charged coupled device (CCD) for detecting the emission of fluorescence intensity from an RT-cPCR mix in a microliter volume glass capillary. Because of its simple mechanism, DNA amplification involves employing the cPCR technique with no need for thermocycling control. The flow pattern and temperature distribution can greatly affect the cPCR process in the capillary tube, a computational fluid dynamics (CFD) simulation was conducted in this study for the first time to estimate the required period of an RT-cPCR cycle. This study also tested the PCR mix containing hepatitis B virus (HBV) plasmid samples by using SYBR Green I fluorescence labeling dye to assess the prototype performance. The measured results from the image-processing scheme indicate that the RT-cPCR prototype with a CCD-based fluorometer can achieve similar DNA quantification reproducibility compared to commercial machines, even when the initial DNA concentration in the test PCR mix is reduced to 10copies/μL

Performance Evaluation of UHF RFID Technologies for Real-Time Bus Recognition in the Taipei Bus Station

Transport stations such as airports, ports, and railways have adopted blocked-type pathway management to process and control travel systems in a one-directional manner. However, this excludes highway transportation where large buses have great variability and mobility; thus, an instant influx of numerous buses increases risks and complicates station management. Focusing on Taipei Bus Station, this study employed RFID technology to develop a system platform integrated with modern information technology that has numerous characteristics. This modern information technology comprised the following systems: ultra-high frequency (UHF) radio-frequency identification (RFID), ultrasound and license number identification, and backstage graphic controls. In conclusion, the system enabled management, bus companies, and passengers to experience the national bus stations new generation technology, which provides diverse information and synchronization functions. Furthermore, this technology reached a new milestone in the energy-saving and efficiency-increasing performance of Taiwans buses.

NOISE REDUCTION OF A CROSS-FLOW FAN

ABSTRACT This study attempts to reduce the aerodynamic sound noise from a cross-flow fan by varying the geometrical parameters of the cross- flow fan as the similar amount of air flow rate is delivered by the cross- flow fan. Two different rotors (fixed-pitch and staggered-pitch) and tongues (wedge- shape and saw-tooth shape), and four different tongue clearances (e=3mm, 5mm, 7mm, and 10mm) are also tested. At Ω≥ 1200 r/min, a screech tone produced from the peak sound pressure levels at the harmonics of blade passage frequency always occurs for the cross- flow fan with the fixed-pitch rotor, the wedge shape, and e=3 mm. At Ω≥1200 r/min, the sound pressure level at the first harmonic of blade passage frequency is significantly reduced by either replacing the fixed- pitch rotor with the staggered-pitch one as well as replacing the wedge shape with the saw-tooth tongue or enlarging the tongue clearance. However, the overall sound pressure level from the cross-flow fan to deliver the same air flow rate is sli...

Simultaneous Quantification for Hepatitis B Virus and Hepatitis C Virus Using Real-time PCR Lab-on-a-chip

The current real-time PCR (polymerase chain reaction) platforms, which can detect and quantify several target DNA simultaneously, are equipped with discrete optics and detectors for different fluorescence wavelengths. However, the optical loss, due to the different lengths of the channels for several dyes, lowers the performance of fluorescence detection. Especially on the PCR platforms of lab-on-a-chip system, for the dispersion of the fluorescence in the micro fluidic channels, the received fluorescence is much lower than the emitted. To enhance the received intensity on the detection system is therefore a critical issue. The proposed fluorescence detection system, composing of an ultra-sensitive spectrometer, can provide continuous wavelength detection and can be employed for multiple DNA quantification and genotyping in a single reaction. For the tests to the genotyping ability, the melting temperatures of B type HBV and C type HBV can be distinguished by the difference of 1.1degC.The test results in this research show the same degree of sensitivity for DNA quantification and reproducibility within five intra assay samples as compared with a commercial one

A novel led driving circuits development for decorative lighting system energy saving

The forward current draft with the temperature changes is a characteristic of LED. This research used this characteristic to achieve control optimization of LED by the forward current feedback. Temperature detection through forward current measurements was applied to LED PWM to carry out the best thermal management of LED arrays under temperature variations, which can offer steady illumination and keep constant chromaticity. LED spotlight products are mainly used for lighting show box display to replace the incandescent lamp which has been forbidden by EU from the year of 2009. Such kind of products now is available on the market. However, the illumination decay and chromaticity changes with operation temperature obstruct wide distribution of LED spotlight for decorative lighting systems. The developed technology by this research can be used to control the chromaticity and the illumination of the LED spotlight and a great niche is outward. This research tested various types of LED are provided by different manufacturers, and the database of the changes of LED chip grains against forward current is build. Constant temperature bath was employed to get the curve of forward current and temperature, which will be a basis of forward current feedback and temperature conversions. Self-developed driving circuits were used to control LED to make the relative illumination decays to be less than 5% and the coordinate excursion of Color rendering index on the CIE chromaticity diagram is lower than 0.1. The circuit control of LED spotlight with low difference of illumination and Color rendering index were therefore successfully realized in this study.