In this paper a piezoelectrically driven silicon membrane pump with passive dynamic valves is described. It is designed to pump gases and liquids and to be tolerant to gas bubbles. Reducing the dead volume within the pump, and thus increasing the compression ratio, one achieves the gas pumping. The main advantages and novel features of the pump described in the paper are the self-aligning of the membrane unit to the valve unit and the possibility of using screen-printed PZT as actuator, which enables mass production and thus low-cost micropumps. A liquid pump rate of 1500 μl min−1 and a gas pump rate of 690 μl min−1 were achieved.

The authors explore the impact of femtosecond light pulses on the field-emission properties of single-gate molybdenum field-emitter arrays with nanometer scale tip apex. Despite the small fraction of the emission area, we observed a single-photon photoelectric current from the emitter tips on top of the dc field-emission current under the irradiation of 50 fs laser pulses at a wavelength of 800 nm with an external quantum efficiency up to ϳ2 ϫ 10 −7 and the emitter tip quantum efficiency of ϳ10 −2. The result indicates that metallic field-emitter arrays are promising for applications that require high-brightness short electron beams.

We have fabricated thermal actuators based on vertical bimorphs, which consist of silicon beams side-coated with aluminium. When they are heated by an electrical current they bend like a bimetal and produce movement in the wafer plane. The fabrication process is based on silicon-on-insulator substrates and uses standard silicon micromachining techniques combined with a special aluminium sidewall deposition process. The displacement has been measured as a function of the input power and the results have been compared with an FEA-simulation.

Thermal vertical bimorph actuators consist of silicon beams side-coated with aluminium. Upon heating they bend like a bimetal and produce movement in the wafer plane. We have measured the time constant describing the deflection response of the actuator to input pulses. Depending on the dimensions of the actuator, the time constant ranges from 0.5 ms to 3.8 ms. Lateral resonances of the first mode have been measured using thermal excitation and are found to be between 20 and 85 kHz.

Articles you may be interested inNanosecond pulsed field emission from single-gate metallic field emitter arrays fabricated by moldinga) J. Vac. Sci. Technol. B 29, 02B117 (2011); 10.1116/1.3569820 Fabrication and characterization of Spindt-type field emission arrays coated with ZrC thin films Full scale simulation of a field-emitter arrays based electron source for free-electron lasers Pulsed field emitted current from different commercial samples in the purpose of a free electron laser application J. Vac. Sci. Technol. B 23, 680 (2005); 10.1116/1.1857892High current, high current density field emitter array cathodesThe properties of the electron source define the ultimate limit of the beam quality in linear accelerators such as free electron lasers ͑FELs͒. The goal is to develop an electron gun delivering beam emittance lower than the current state of the art. Such a gun should reduce the cost and size of an x-ray FEL ͑XFEL͒. In this article we present two concepts of field emitter cathodes which could potentially produce low emittance beam. The first challenging parameter for such cathode is to emit peak current as high as 5 A. This is the minimum current requirement for the XFEL concept from Paul Scherrer Institut ͑http://leg.web.psi.ch͒. Maximum currents of 0.12 and 0.58 A have been reached, respectively, with field emitter arrays and single needle cathodes. Laser assisted field emission gave encouraging results to reach even higher peak current and to prebunch the beam.