A novel multi-channel detection system for real-time PCR machine is proposed in this study. The prototype in this article is equipped with a spectrometer which has the bandwidth of visible light, hence there are more than 6 channels can be detected simultaneously. In contrast to the traditional Real-Time PCR machine with discrete fluorescence wavelength detection channels, the prototype is equipped with continuous fluorescence wavelength detecting ability to multiplex Real-Time PCR. In this study, a HBV DNA template with LC-Red 640 dye and the Internal Control DNA template with LC-Red 705 dye were employed for DNA quantification experiments. The results show that this prototype provides comparable accuracy and reproducibility as the commercial system for DNA quantification with the DNA quantification and detection method proposed in this study.
This study presents a novel method based on the surface acoustic wave (SAW) sensor, for monitoring the thickness of a silicon membrane in real time during wet etching. Similar to accelerometers and pressure sensors, some micro-electro-mechanical systems (MEMS) devices require the thickness of silicon membranes to be known precisely. Precisely controlling the thickness of a silicon membrane during wet etching is important, because the thickness strongly affects post-processing and device performance. Moreover, the proposed surface acoustic wave sensor allows the thickness of a silicon membrane to be monitored from a few μm to hundreds of μm in situ, which depends on the periodicity of interdigital transducers (IDT). A novel method, which differs from any in previous work on etch-stop techniques, is developed in-situ for monitoring the thickness of a silicon membrane during wet etching. In summary, the proposed method for measuring the thickness of a silicon membrane in real time, is highly accurate; is simple to implement, and can be mass-produced. This work also describes the principles of the method used, detailed process flows, the method of taking measurements and the simulated and experimental results. The theoretical and measured values differ by an error of less than 2.50μm, so the results closely agree with each other.
This work presents the micro-machined 2-D switch array for use on free-space optical interconnect platform integrated with a digital 1x8 de-multiplexer control circuit together. Moreover, this device employs electrostatic actuation for light beam directions control. The CMOS-MEMS array-based optical platform contains 10x10 circular micromirrors switching spots, the diameter of each mirror is about 50 μm and the overall chip size is around 2 mm by 2 mm. The commercialized simulation softwares were used to validate the micromirror design and elucidate the behavior of the micromirror before fabrication. The post-process simply employs HF based solution to etch silicon dioxide layer to release the suspended mirror structures. The micromirror array is actuated using an electrostatic force. The results reveal that the micromirror has a tilting angle of around 8° according to the triangular relation with a driving voltage of 18V at pull down state. Also described herein are the general principles of the light-beam switching method used, the detailed of device design, the post-CMOS fabrication process flow, the result of simulations and preliminary experimental results are discussed.
A high precision alignment of mask pattern to crystal orientation is essential for fabricating most micro- mechanical devices. With an accurate alignment on a silicon wafer, the time for obtaining a smoothly etched sidewall surface can be reduced and the undercut phenomenon can also be minimized during the anisotropic etching process. In this article, a series of circles are made as an aligning pattern. These circles are evenly distributed at each 0.1 degrees along the same arc of radius 43mm. A wafer is etched in the TMAH solvent for a certain period of time, and the final etched pattern is served as an alignment mark. The present method relies upon the fact that when a (100) silicon wafer is etched for a sufficiently long period of time in an orientation-dependent etchant through a circular window, the etched out portion will form a cavity of pyramidal shape with its surfaces along the (110) directions because the etching process is almost stopped at the (111) planes. However, this pyramidal cavity will continue to grow along the (111) direction when the etching process is continued. This is caused by the undercut phenomenon occurred at the contact line of the passivation layer and the Si substrate. Despite of the circular window used on the passivation layer, the top view of the pyramidal cavity caused by undercut on the Si substrate will be a square opening. Through a visual inspection from the top view, one can find that the corners of some neighboring square openings contact to each other but some are not after a sufficient time of etching. The contact proximity at the corners of two neighboring square openings is taken as an accurate rule for the wafer's alignment. Such a pre-aligning pattern allows one to determine the (100) orientation within accuracy of 0.05 degrees.
The evaporation of thin liquid films is of significant importance in a wide variety of heat transfer problems. The vaporization process of thin liquid films in a trapezoid microgroove channel was investigated both numerically and experimentally. In order to predict the wetted axial length of capillary flow in a trapezoid microgroove, the nonlinear governing equation was solved numerically and a simplified algebraic equation was also derived. The parameters include the input heat flux, tilt angle of grooved surface, thermophysical properties of working fluid, and geometric parameters of microgrooves. In order to investigate the effect of geometric parameters of microgrooves on the wetted axial length, a series of either trapezoid or triangular microgrooves was machined on the surface of copper test devices for experimental measurements. Measurements were conducted using either methanol or ethanol as working fluid at four different tilt angles of grooved surface and four applied input heat flux values. The wetted axial length was measured using microscopy observation. The predicted results of the algebraic equation are found to be in reasonable agreement with the experimental data, especially for cases of higher tilt angle or higher heat flux. Besides, using microgrooves of triangular shape or using methanol as working fluid can increase the wetted axial length of microgrooves.
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