Combination of Micro-fluidic Chip with Fluorescence Correlation Spectroscopy for Single Molecule Detection

A single molecule detection technique was developed by the combination of a single channel poly （dimethylsiloxane）/glass micro-fluidic chip and fluorescence correlation spectroscopy （FCS）. This method was successfully used to determine the proportion of two model components in the mixture containing fluorescein and the rhodamine-green succinimidyl ester.

Research of Confocal Laser Induced Fluorescence Detection System for Micro-fluidic Chip

The characteristics such as signal noise ratio（SNR） and sensitivity of the fluorescence detection system for micro-fluidic chip influence the performance of the whole system extremely. The confocal laser induced fluorescence detection system is presented. Based on the debugging of optical and circuit modules, the results of detecting the samples are given and analyzed theoretically, and the improved project is put forward.

Investigation into the hydrodynamics of liquid-solid inclined micro-fluidized beds

The inclined micro-fluidized bed(MFB)can enhance heat and mass transfer rates compared to the vertically aligned counterparts,but the increased significance of surface forces and wall effects may cause poor fluidization performance.In this paper,the effects of column inclination and different particle-to-bed ratios(d_(P)/d_(B))on the solid hydrodynamics are investigated in an inclined micro-fluidized bed.The results validated the suitability of using the Ergun equation to predict minimum fluidization velocities due to small deviations between 1.01 and 1.81 times the theoretical values,for a particle-to-bed ratio ranging from 0.025 to 0.165 at inclinations between 0°and 10°.Investigation into the effects on bed expansion behavior showed that the bed contracted with an increase in bed inclination.An unexpected observation during the bed expansion was the appearance of a secondary high voidage region and the appearance of strong circulation patterns with an increase in bed inclination.A detailed analysis of this phenomenon suggested the presence of a critical angle at 6°and 10°for the 85μm particles,4×4 mm bed cross-section and 165μm particles,1×1 mm bed cross-section,respectively.However,the liquid-solid back-mixing was observed due to the modified particle trajectories resulted in the disappearance of the high voidage region.This paper gives new insights into the micro-fluidization behavior in inclined beds thus contributing to the development of micro-fluidized beds and their future applications.

Thermoelastic vibration analysis of micro-scale functionally graded material fluid-conveying pipes in elastic medium

Micro-scale functionally graded material(FGM)pipes conveying fluid have many significant applications in engineering fields.In this work,the thermoelastic vibration of FGM fluid-conveying tubes in elastic medium is studied.Based on modified couple stress theory and Hamilton’s principle,the governing equation and boundary conditions are obtained.The differential quadrature method(DQM)is applied to investigating the thermoelastic vibration of the FGM pipes.The effect of temperature variation,scale effect of the microtubule,micro-fluid effect,material properties,elastic coefficient of elastic medium and outer radius on thermoelastic vibration of the FGM pipes conveying fluid are studied.The results show that in the condition of considering the scale effect and micro-fluid of the microtubule,the critical dimensionless velocity of the system is higher than that of the system which calculated using classical macroscopic model.The results also show that the variations of temperature,material properties,elastic coefficient and outer radius have significant influences on the first-order dimensionless natural frequency.

Detection of CEA mRNA in patients with non-small cell lung cancer and it’s significance

Objective: To detect the expression of CEA mRNA in patients with non-small cell lung cancer (NSCLC) and to investigate it's significance. Methods: The blood samples were taken from peripheral veins of 70 patients with NSCLC and 18 patients with benign diseases at 3 intervals during the surgery. The transcription of carcinoembryonic antigen messenger ribonucleic acid (CEA mRNA) was assayed by means of nested reverse transcriptase polymerase chain reaction (RT-PCR) and micro-fluid chip. Results: The CEA mRNA positive rates at each of the 3 time spots were as follows: 50% at beginning of the surgery (group 1), 62.8% in the samples collected when ligating the pulmonary vein (group 2) and 57.1% in samples collected 1 h after ligation (group 3). A significant difference was found between groups 1 and 2 (χ2 = 7.114, P < 0.05). Con-clusion: Cancer cell dissemination during surgery is demonstrated indirectly in our study, when to ligate the pulmonary vein (earlier or later) may affect the quantity of tumor cells spread into the circulation.

Two-fluid modeling of Geldart A particles in gas-solid micro-fluidized beds

The fiuidization behavior of Geldart A particles in a gas-solid micro-fluidized bed was investigated by Eulerian-Eulerian numerical simulation. The commonly used Gidaspow drag model was tested first. The simulation showed that the predicted minimum bubbling velocities were significantly lower than the experimental data even when an extremely fine grid size （of approximately one particle diameter） was used. The modified Gibilaro drag model was therefore tested next. The predicted minimum bubbling velocity and bed voidage were in reasonable agreement with the experimental data available in literature. The experimentally observed regime transition phenomena from bubbling to slugging were also reproduced successfully in the simulations. Parametric studies indicated that the solid-wall boundary conditions had a significant impact on the predicted gas and solid flow behavior.

Kinetics of Reduction Reaction in Micro-Fluidized Bed

Micro-fluidized bed reactor is a new research method for the reduction of iron ore fines. The reactor is op- erated as a differential reactor to ensure a constant gas concentration and temperature within the reactor volume. In order to understand the dynamic process of the reduction reaction in micro-fluidized bed, a series of kinetic experi- ments were designed. In the micro fluidized bed, the use of shrinking core model describes the dynamic behavior of reduction of iron ore. And the apparent activation energy is calculated in the range of 700--850 ~C while the initial atmosphere is 100% content of CO.

Hydrodynamic behavior of liquid-solid micro-fluidized beds determined from bed expansion

The bed-expansion characteristics of liquid-solid micro-fluidized beds were experimentally studied. Bed columns with inner diameters of 0.8, 1.45, and 2.3 mm were fabricated based on capillaries. Five parti- cle sizes in a range of 22-58 t^m were investigated. Bed-expansion curves were plotted using visually recorded bed-expansion heights. The bed expansion and initial fluidization behavior were compared with predictions for conventional-scale beds, Evident differences are reflected in lower expansion ratios and higher minimum fluidization velocities for micro-fluidized beds. These were attributed to the increase in the internal surface area of the particle beds and specific surface area of wall contact. The wall effect for micro-fluidized beds at higher particle/bed diameter ratios caused higher local voidage and an increase in expansion ratio. Correlations for the exponent and proportional coefficient in the Richardson-Zaki equation for micro-fluidized beds were proposed. The minimum fluidization velocities were correlated using a modification of the Ergun equation.

Studying the current properties of buffer solution through micro-fluidic channels driven with the pulse bias

In the research of bio-molecular chips and sensors, extra electric biases are most often employed to control and manipulate the DNA and protein molecules moving through micro/nano-fluidic channels. In order to accurately and flexibly control the bio-molecules as they move within the channels, a clear understanding of how the current changes within the buffer solution caused by an applied bias is fundamental. In this report, the current changed value of different buffer solutions, e.g., KC1, TE, and TBE was systematically studied with real-time monitoring and quantitative analysis in the situation of the buffers moving through a fluidic channel with a 5 μm inner diameter, driven by biases of 50 or 100 mV. The results revealed that the relation- ship between the current changed value and the pause interval of the applied electric field is highly consistent with the Hill Equation, which is helpful for accurately detecting and manipulating single biomolecules in microfluidic sensors and biochips.

Research on critical technology of micro/nano bioparticles manipulation platform based on light-induced dielectrophoresis

On the basis of the research on the status and problems of micro/nano bio-particles manipulation using dielectrophoresis, the theoretical basis and the model simulation of micro/nano bio-particles manipu-lation using light-induced dielectrophoresis were discussed. The space distribution of electric field and dielectrophoresis forces in different heights were also obtained. On this basis, the core component of the micro manipulation system, that is, photoconductive layer of the chip, was completed in the mate-rial selection, fabricating process and performance analysis testing. Then the voltage drop of the sus-pension and the effective voltage frequency spectrum were obtained. Finally, by combining the machine vision detection with real-time tracking system, the micro/nano bio-particles manipulation platform based on the light-induced dielectrophoreisis was established, and then the manipulations for micro/nano bio-particles, such as quick collection, transport, separation, were implemented. This provided a basis for rapid, accurate, and low-cost detection of serious diseases based on the micro-fluidic biochip and early diagnosis.