A novel air-flow generator based on the effect of ion wind has been developed by the simultaneous generation of both positive and negative ions using two electrodes of opposite polarity placed in parallel. Unlike the conventional unipolar-generators, this bipolar configuration creates an ion wind, which moves away from both electrodes and yields a very low net charge on the device. The electro-hydrodynamic behaviour of air-flow has been experimentally and numerically studied. The velocity of ion wind reaches values up to 1.25 m/s using low discharge current 5 μA with the kinetic conversion efficiency of 0.65% and the released net charge of -30 fA, 8 orders of magnitude smaller compared with the discharge current. Due to easy scalability and low net charge, the present configuration is beneficial to applications with space constraints and/or where neutralized discharge process is required, such as inertial fluidic units, circulatory flow heat transfer, electrospun polymer nanofiber to overcome the intrinsically instability of the process, or the formation of low charged aerosol.

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This paper presents the development of a gas-jet micropump with different cross-junctions and integrated hotwire. The device is actuated by a piezoelectric lead zirconate titanate (PZT) diaphragm at its resonant frequency. The design focuses on a cross-junction formed by the intersection of the channels and neck of the pump chamber, which allows differences in fluidic resistance and fluidic momentum during each PZT diaphragm vibration cycle and thus enables rectification of the gas without valves. Three different designs were investigated by utilizing the ANSYS-FLUENT software. Simulations and experimental data revealed that the step nozzle structure with anti-choking space has much more advantages than the others. The device has been fabricated by the standard MEMS process, and the tiny hotwire has been realized together with the fluidic network. Experiments have been carried out. At a driven frequency of 7.9 kHz, a flow rate of 5.2 ml min−1 was obtained with an applied sinusoidal voltage of 50 Vp-p. The output voltage on the hotwire was measured to be 130 mV at a constant current of I = 0.1 mA.

We present a simple and efficient airflow generator utilizing the effect of ion wind by generating simultaneously both the positive and negative ions from two sharp electrodes mounted parallel to each other. The unique bipolar geometrical setup eliminates the effect of space charge by the high recombination rate of oppositely charged ions. The two-electrode arrangement is symmetrical, where the electrode creating charged ions of one polarity also serves as the reference electrode to establish the electric field required for ion creation by the opposite electrode, and vice versa. Unlike the conventional setup, with a single electrode generating ion wind with movement toward the reference electrode, in this configuration the air movement is parallel to the electrodes, and is directed away from the device. The airflow behavior is studied by both experiments and numerical simulation. The ion wind speed has a linear relationship with the square root of the discharge current, U ∝ √ I, and its measured values agree well with simulation. The characterization of the discharge current-voltage relationship was derived from mathematical processing in the general formThe ion wind speed and the current-voltage characteristics depend on the interspace between the electrodes and the electrode geometry. An ion wind speed on the order of ms −1 is created with a microampere discharge current, resulting in a total net charge of only several femtoampere. The proposed configuration is beneficial in minimizing the power consumption of the system, and in enabling air recirculation for airflow control applications, cooling applications, propulsion technology, and micropump design, especially for the applications where neutralized ion wind flow is required.Index Terms-Bipolar corona discharge, electrohydrodynamics, ion wind, parallel pin.0093-3813 of Engineering and Technology, VNUH. He has authored or co-authored more than 60 scientific articles and seven inventions. His current research interests include 3-D system integration technology and MEMS-based sensors, actuators, and applications.