The design of a novel, microfluidic chip with an integrated micro peristaltic pump and chambers for DNA amplification is described. This chip contains three reaction chambers stable at 90 • C, 72 • C and 55 • C for PCR amplification, a bi-directional peristaltic pump and optical integrated detection of the droplet. A reactant droplet is to be introduced into the device, pumped back and forth between the chambers by the micro peristaltic pump for sample processing. The static behaviour of the micro pump was modelled theoretically in order to evaluate the optimal dimensions for the pump membranes and to obtain the maximum flow rate. Thermal analysis by the finite element method was performed to optimize the location of the heaters and the temperature uniformity over the three reaction chambers. Transient thermal analysis indicates that the reactant droplet can be heated/cooled in the proposed device in less than 1 s to achieve the desired temperatures.

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A new silicon-based micropump is described in this paper. The key element of the device is a thick-film/silicon micromachined hybrid actuator. The actuation principle relies on the flexure of a screen printed piezoelectric lead zirconate titanate (PZT) layer on a silicon membrane ( 8 mm X 4 mm X 70 km). An investigation into the deposition technology of the bottom electrode for the piezoelectric material showed that a gold resinate or Pt evaporated electrode on a 500 nm thick SiQ covered silicon wafer achieved best results for the membrane actuator. Met and outlet valves are of the cantiiever type and use deep boron diffusion together with KOH etching. Pump rates of up to I20 ~1 min-' have been achieved. A maximum backpressure of 2 kPa was measured when using a 600 V,, sinusoidal drive voltage at 200 Hz across a 100 pm thick PZT layer. The pump was compared with a conventional surface mounted piezoelectric driven micropump. The conventional pump achieves a performance which was a factor of 3-6 more efficient, but does not allow mass production, 0 1998 Elsevier Science S.A. AU rights reserved.

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This paper reports the design and fabrication of a micromachined Coulter counter. Calculations have been performed to estimate the behaviour of the counter for passing particles. A relative resistance change of 1.8% has been derived for a particle of 1.5 µm radius flowing through a capillary of 5 µm side length and an electrode spacing of 40 µm. The fabrication technology has been based on similar micromachining steps to a micromixer, and allows further design modification to generate other microfluidic devices. Thus, integration of other microfluidic devices is possible with this technology. The fabrication relies on silicon trench etching and subsequent deposition of metal electrodes over the trench edges. Finally, a Pyrex wafer is anodically bonded on top of the silicon to seal the capillaries.