Guangyu Du

Experimental Study on Noise Reduction of Multistage Dry Roots Vacuum Pump Varying the Amount of Dynamic Unbalance

Multistage dry Roots vacuum pumps (MDRVPs) are vacuum equipments widely used in IC industry. This paper analyzes the influence mechanism of dynamic unbalance to vibration and noise of rotor axis in MDRVPs, and calculates the vibration deformation of the rotor axis caused by dynamic unbalance through the finite element method. Moreover, a series of experiments on noise source identification are carried on a MDRVP sample machine varying the amount of dynamic unbalance. Through the experimental results, conclusions are drawn that the periodic incentives generated by the unbalance of rotor axis are the main attribution of vibration and noise. Therefore the noise reduces when the amount of unbalance of rotor axis deceases. However, when the allowable unbalance of the rotor axis decreases to a certain degree, aerodynamic noise generated at the outlet becomes the main noise with dominant frequency. It is true that noise of MDRVPs should be no more than 72dB, so the allowable amount of dynamic unbalance should be chosen at a moderate lever as 1.0 g•mm/kg. In that way, this conclusion offers a rule for MDRVPs design and dynamic balance operation because this lever would not only meet the demand of noise reduction but also save working hours and cost for dynamic balancing.

A Microfluidic Chip with Double-Slit Arrays for Enhanced Capture of Single Cells

The application of microfluidic technology to manipulate cells or biological particles is becoming one of the rapidly growing areas, and various microarray trapping devices have recently been designed for high throughput single-cell analysis and manipulation. In this paper, we design a double-slit microfluidic chip for hydrodynamic cell trapping at the single-cell level, which maintains a high capture ability. The geometric effects on flow behaviour are investigated in detail for optimizing chip architecture, including the flow velocity, the fluid pressure, and the equivalent stress of cells. Based on the geometrical parameters optimized, the double-slit chip enhances the capture of HeLa cells and the drug experiment verifies the feasibility of the drug delivery.

Computer modeling of electric potential distribution of ion transport in rectangular Nanofluidic Channel

Based on continuity assumption of fluid, we established a mathematical model of ion transport in the rectangular Nanofluidic Channel with Poisson-Boltzmann equation and modified N-S equations. Through equation derivation, the electric potential distribution function was solved. Next we analyzed how the distribution of the ion electric potential distribution was charged by the solution concentration, the surface charge density and the channel height. Thus we have got the curves between Electric potential distribution and these parameters. Therefore, the main influential factors of the electric potential are the electrolyte concentration, the surface charge density and the channel height. By adjusting the electrolyte concentration, the surface charge density and the nanofluidic channel height, we can control the electric potential.