An extremely sensitive fluorescent sensor based on a phenylboronic acid monolayer was developed for detecting
saccharide molecules. The fluorescent sensor was prepared by assembling a monolayer of 4-mercaptophenylboronic
acid (4-MPBA) onto a gold-coated compact disk. The change in the fluorescence of the 4-MPBA monolayer was
extremely obvious in basic methanolic buffer containing monosaccharides down to the picomolar level. The
fluorescence spectra demonstrated that the 4-MPBA monolayer was sensitive to monosaccharides and disaccharides, and
the affinity of the monolayer toward saccharides was in the order of glucose < fructose < mannose < galactose < maltose > lactose > sucrose. Additionally, the fluorescence intensity of 4-MPBA monolayer was restorable after cleaning with weak acid, indicating that the reported fluorescent sensor with the detection limit of glucose down to the picomolar level is reusable for sensing saccharides.
Fluid driven devices have been widely used in many applications, such as pumping, circulating, and cooling systems in
handling liquid. Their driving conditions are highly dependent on the operation purposes. Some of them work with high
pressure and high flow rate without the need of flow stability. On the other hand, the steady flow with low pressure and
flow rate is required for bio-applications. In a perfusion system for culturing cells, a suitable shear stress from a
cultivated fluid is one of key factors to reproduce the fluid conditions of cells in a living organism. A special pump is
needed to provide a steady flow rate and stress in such system. In this study, a novel design of the pump constituted by a
housing and a screw-type rotor with micro-channels was proposed. To understand the flow phenomena in this design,
both computational modeling and real experiment are utilized. In the experiment, a minimum rotational speed is needed
to drive the fluid flow. In the modeling, the steady state with low pulsation was achieved within a short period of time. A
perfusion system with 7.8% variation in flow rate could be obtained in comparison with traditional peristaltic pump with
up to 29% variation in flow rate. Steady fluid flow for a perfusion system then could be obtained in this screw-type
pump.
The modified optical disc process has been investigated and demonstrated to enable fast prototyping in fabricating molds
and replicating substrates with various microstructures including micro-chambers and micro-channels. A disc-like microfluidic
device was created and the testing results showed good performance in bonding and packaging. The switching of
the nozzle-like micro-valve was also validated to work well. Furthermore, the relevant procedures of liquid samples
loading, separating and mixing were also accomplished through food experiments.
KEYWORDS: Optical components, Optical sensors, Optical encoders, Head, Chemical elements, Optics manufacturing, Signal detection, Signal generators, Optical design, Control systems
Optical encoders are widely used to detect the position, angle or speed in precise control systems. A rotary optical
encoder mainly comprises an optical sensor and an optical grating element with a fine grating pitch. In order to improve
the resolution of rotary optical encoders, the grating pitch in the optical grating element should be reduced as small as
possible. That is, the pulse per revolution (ppr) in the optical grating element must be increased markedly. However, an
optical grating element having over 10,000 ppr is difficult to achieve by traditional methods. In this paper, a novel
method is proposed and demonstrated to replicate an optical grating element with a high ppr. Furthermore, the tiny
signals generated from fine grating pitches in the optical grating element have been also measured by using a
conventional optical pickup head.
Total internal reflection fluorescence microscopy (TIRFM) induces the evanescent field from an incident light with an incident angle greater than the critical angle selectively to excite fluorescent molecules on or near a surface. The TIRFM not only provides enhanced understanding of cellular function but also improves signal-to-noise ratio of detecting signal in real time. However, fluorescent emission need to be increased when a dynamic biomolecular image is requested at the frame rate of greater than 100 frames/s. Therefore, the fluorescent signal is enhanced via surface plasmons to match the requirements of better efficiency and larger quantity. In this study, a plasmon-enhanced TIRFM whose operation is based on the electromagnetic field enhancement via surface and particle plasmon effects offered by a nano-scalar silver thin film and particles has been presented. The developed microscopy has been successfully used in the real-time observation of the enhanced fluorescence from the thrombomodulin protein of a living cell membrane. The simulated and
experimental results demonstrate that the plasmon-enhanced TIRFM can provide brighter living cell images through surface plasmon enhanced fluorescence.
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