受约高分子PDMS链构型的热力学性质的研究

采用统计力学方法,将长链ＰＤＭＳ分子作为一个约束在圆柱体内的小体系进行了处理,利用计算机进行模拟ＰＤＭＳ链的动态过程和处理矩阵连乘,坐标转换,得出受约有限长度高分子链的配合函数表达式及熵的表达式。这为进一步研究多链体系的热 性质提供一种方法。     

光纤型微流控电泳芯片的研制

介绍了一种光纤型微流控电泳芯片,该芯片主要由两部分组成:多模光纤,PDMS基片和盖片.利用二次曝光技术制作出芯片的模具;通过浇注的方法制成电泳芯片;实现了在PDMS上制作深度不同的微流控沟道和光纤沟道,使光纤与微流控沟道能够方便地对准;利用异硫氰酸酯荧光素考察了系统的性能,最小检测浓度达到1.3×10-7mol/L,信噪比S/N=5.     

Towards a re-programmable DNA computer

Microreactors lend themselves to a relatively simple implementation of DNA computing. Not only is the design of the DNA library critical for the success of the system but also the architecture of the microfluidic structure. Microreactors can be configured as Boolean operators. This paper will show that biomolecular computing can be performed with elementary building blocks, analogous to electronic logic gates. These logical operations will be performed using negative selection. Furthermore, an alternative bead barrier is introduced which can render the computer re-programmable and shows an principle architecture for selection and analysis.     

聚硅氧烷嵌段共聚物中微相分离的计算机模拟

通过RIS Metropolis Monte-Carlo方法建立了PDMS、PDPS以及嵌段共聚物PDMS/PDPS的模型,并用COMPASS力场和智能最小化方法对模型进行了能量最小化计算。采用共混相图、红外光谱和X射线的方法研究了PDMS/PDPS嵌段共聚物的微相结构,结果表明PDMS和PDPS存在微相分离现象;在PDMS/PDPS共聚物结构中,稳定的螺旋结构在与具有无规线团结构的PDMS共聚后,受到部分破坏,形成了新的无规线团区,具有特定的微相结构。     

Flow simulation in Electro-Static-Precipitator (ESP) ducts with turning vanes

Flow simulation in inlet ducts along with several turning vanes used in electrostatic precipitator (ESP) are analysed to understand the flow pattern at its exit locations. The geometry of inlet duct has been extracted from the Plant Design Manufacturing System (PDMS) and refined with turning vanes placed at several locations. The domain of duct geometry around turning vanes are decomposed with several volumes and filled with hexahedral elements with the help of stat-of-art mesh generator - Hypermesh. The resulting computational grid has been used in TASCflow solver to predict its flow pattern in the duct. Simulation for the specified conditions predicts uneven flow distribution in the ESP inlet duct. Due to large flow recirculation and turbulent losses in the duct, non-uniform averaged mass flow rates are noticed at duct exit locations. Simulation results suggest that the improvement of flow distribution in the duct through optimization can be tried by placing more turning/splitter vanes in the inlet duct. In order to ensure that the results obtained from TASCflow are meaningful and in right direction, in the absence of measurement data, simulation was benchmarked with other industry standard commercial flow solvers. The observations made from these popular solvers confirm the findings obtained using the TASCflow solver. The analysis with multiple solvers indicates that Fluent provides quick results, while better visualization can be made using CFX solver. The Star-CD solver, which captures the turbulent losses accurately takes more time for convergence provides alternatives.     

Fluorescence detection in a micro flow cytometer without on-chip fibers

This paper describes a novel concept of integrated on-chip fiber free laser-induced fluorescence detection system. The poly-dimethylsiloxane (PDMS) chip was fabricated using soft lithography and was bonded with a glass substrate of 150 μm thickness that reduced the distance of channel-to-sidewall to less than 180 μm. The cells and particles detection was conducted by an external single fiber close to the glass substrate that transmitted laser light for simultaneous excitation and receipt of the emission light signals. The performance of the proposed device was demonstrated using fluorescence beads, stained white blood cells, and yeast cells. The experimental results showed the simplicity and flexibility of the proposed device configuration which can provide convenient on-chip integration interface for fast, high throughput, and low-cost laser-induced fluorescence detection micro flow cytometer.     

The microscopy cell (MicCell), a versatile modular flowthrough system for cell biology, biomaterial research, and nanotechnology

We describe a novel microfluidic perfusion system for high-resolution microscopes. Its modular design allows pre-coating of the coverslip surface with reagents, biomolecules, or cells. A poly(dimethylsiloxane) (PDMS) layer is cast in a special molding station, using masters made by photolithography and dry etching of silicon or by photoresist patterning on glass or silicon. This channel system can be reused while the coverslip is exchanged between experiments. As normal fluidic connectors are used, the link to external, computer-programmable syringe pumps is standardized and various fluidic channel networks can be used in the same setup. The system can house hydrogel microvalves and microelectrodes close to the imaging area to control the influx of reaction partners. We present a range of applications, including single-molecule analysis by fluorescence correlation spectroscopy (FCS), manipulation of single molecules for nanostructuring by hydrodynamic flow fields or the action of motor proteins, generation of concentration gradients, trapping and stretching of live cells using optical fibers precisely mounted in the PDMS layer, and the integration of microelectrodes for actuation and sensing.     

The influence of loose and semianchored siloxane polymer chains on the tack of crosslinked silicone rubber

The influence of addition of nonreactive silicone oil or semianchored silicone polymer on crosslinked poly(dimethylsiloxane) (PDMS) rubber–rubber adhesion was studied. The additives can be considered either a tackifier, or connector molecules, able to cross the interface and entangle. In both cases, it influences the tack of the elastomers. An additional variable is the molecular weight of the additive, which affects the reptation of the polymer chains. Polymer–polymer demixing, which is the result of thermodynamic incompatibility of mixed polymers is another factor that influences tack. It causes the free chains to appear at the surface forming a layer of oil, which actually destroys the tack of the PDMS samples. The resulting tack phenomena as a function of oil, respectively semianchored silicone polymer chains, are very much dependent on the transient nature of the polymer reptation: in many cases the polymers need very long time periods to obtain equilibrium in interphase crossing, or oil sweats out of the crosslinked polymers, forming a liquid layer between the two phases resulting in a low tack value, due to hydrodynamic wetting alone. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Surface Mechanical Properties of the Spore Adhesive of the Green Alga Ulva

The mechanical properties of the adhesive produced by spores of the green, marine, fouling alga Ulva linza are reported. Atomic force microscopy studies were performed and nanoindentation data were analyzed using a model for an asymmetric indenter. Freshly secreted adhesive is characterized by multiple layers. We found that the modulus of the outer ∼600-nm thick layer was about 0.2 ± 0.1 MPa, whereas the modulus of the inner layer was about 3 ± 1 MPa. Older adhesive showed the formation of a “crust” of harder material with a yield strength of ∼20 MPa at a loading rate of 2.5 × 10^-6 N · s^-1. Mechanical properties under tension are also described, and extension profiles that showed either constant or nonlinear force changes with tip-sample separation were observed. Models for both kinds of behavior are described. The work of adhesion between poly-dimethylsiloxane (PDMS)-coated AFM tips and the adhesive was determined to be less than 1.5 mJ · m^-2.     

Experimental study on a single particle trap with a pneumatic vibrator matrix

This paper describes a fundamental study on a pneumatic particle trap with a vibrator matrix. The particle trap device consisted of pneumatic vibrators and a trap chamber used to trap a particle. The entire structure was fabricated from polydimethylsiloxane (PDMS). The particle in the trap chamber was manipulated and trapped in the equilibrium region by exploiting the geometrical symmetry of the vibrators. The x-axial velocity of the viscous fluid induced by the deformation of the flexible diaphragms was eliminated or minimized at the center of two vibrators. Therefore, a particle could be trapped in the central capturing region by two or four vibrators. The trapping of static and dynamic single particles was observed to verify the proposed operational method.