Ao Hongrui

Electrohydromechanical analysis based on conductivity gradient in microchannel

Fluid manipulation is very important in any lab-on-a-chip system. This paper analyses phenomena which use the alternating current (AC) electric field to deflect and manipulate coflowing streams of two different electrolytes (with conductivity gradient) within a microfluidic channel. The basic theory of the electrohydrodynamics and simulation of the analytical model are used to explain the phenomena. The velocity induced for different voltages and conductivity gradient are computed. The results show that when the AC electrical signal is applied on the electrodes, the fluid with higher conductivity occupies a larger region of the channel and the interface of the two fluids is deflected. It will provide some basic reference for people who want to do more study in the control of different fluids with conductivity gradient in a microfluidic channel.

Modeling of micro-friction in a multi-layer metal plate damper for a rotor support system

The energy dissipation of multi-layer metal plate damper is realized by dry friction caused by the micro-motion between adjacent layers when the damper is deformed. In the study, the damper is modeled with a single layer continuous beam with uniform thickness, in which the stress status is analyzed when the damper is deformed. The contact surface of the beam is simplified to discrete elements to analyze the energy dissipation based on Mindlin model. A finite element model is used to simulate the energy dissipation process to rectify the theoretical calculation. Considering the distribution and the intensity of the friction force at the contact area, the simulated results of micro friction on the contact surface have the good agreement with the experimental ones, which is beneficial to the wear and failure analysis of the multi-layer metal plate damper.

Study on automatic power control in FES cycling

In order to improve the performance of the lower-limb FES cycling, a method of measuring the automatic control Power in the cycling was developed based on the estimation of dynamic models of the response from muscle stimulation intensity to power. The identified models were used for analytical design of feedback controllers. The results showed that this method had ability to achieve an accurate control of power and track arbitrary signals obtained from healthy adults, which shows its feasibility to the experiment on the paraplegic.

Effects of thermal deformation of the head and the heater on the pressure of HDI

In this study the static characteristics are analyzed with consideration of the convection heat transfer between the fluent and the solid, and the thermal-induced deformation of solid. The pressure, temperature and thermal deformation at head/disk interface (HDI) are simulated. The steady state characteristics of the interface of the head and disk are obtained.

Dielectrophoresis of Electroless Gold Plating Polystyrene Microspheres

Micro spheres with perfect conductive surface have many advantages in biosensor and MEMS devices research. Polystyrene micro spheres were coated gold shell perfectly using electroless gold plating method and the scanning electron microscope (SEM) images were obtained detailedly. Dielectrophoresis (DEP) model of single sphere and signal shell sphere were set up and the real part of the Clausius-Mossotti factor for the two kinds of micro spheres were calculated. Experiments on the DEP characterization for the native polystyrene micro spheres and gold coated polystyrene micro spheres (GCPM) were measured and the results show that the GCPM can only be acted by positive DEP force when the order of the frequency is below 1012 Hz. The experimental results and the theory prediction have a good agreement.