A numerical design study of the valveless diffuser pump using a lumped-mass model

Abstract

This paper presents a lumped-mass model especially developed for valveless diffuser pumps. It is implemented using MATLAB. The model is tested for different previously reported valveless diffuser pumps and shows good agreement with the experimental results. The model predicts the flow-pressure characteristics for different excitation levels. The model makes it possible to study flows and pressures inside the pump. The simulations show that the maximum excitation level for the valveless diffuser pump is probably limited by low chamber pressure. Modified designs are tested and it is shown that a pump with two serially connected pump chambers working in anti-phase is advantageous compared with a single chamber pump for both the maximum volume flow and maximum pump pressure. The simulations also indicate that scaling down the diffuser elements from an 80 × 80 µm 2 throat cross-sectional area to a 40 × 40 µm 2 throat cross-sectional area probably increases the attainable pressure head.

A PMMA valveless micropump using electromagnetic actuation

“…The combination of the nozzle/diffuser elements with an electromagnetically actuated PDMS membrane, characterized by a large deflection amplitude, resulted in a self-priming micropump with which we successfully pumped both water and air. Its flow rate-backpressure performance has been characterized and the micropump resonance frequency showed good agreement with the theoretical models of Olsson et al (1999) and Pan et al (2003). The frequency-dependent flow rate can be well understood by a fluidic damped oscillator model.…”

“…Our experiments are the first ones that directly demonstrate the damped resonance behavior of a nozzle/diffuser micropump. Although resonance frequencies are correctly predicted by the models of Olsson et al (1999) and Pan et al (2003), the damping behavior is strongly underestimated in the theory of Pan. Indeed, to correctly fit our experimental data, the losses in the theory of Pan need to be overestimated by a factor 100.…”

“…A resonance frequency of $12 Hz can be observed. For water pumping, the resonance frequency of a nozzle/diffuser reciprocating pump was theoretically calculated by Olsson et al (1999). They used an energy analysis technique, where the total energy (not taking into account losses) oscillates between the maximum kinetic energy of the fluid in the nozzle/diffuser element and the maximum potential energy of the diaphragm.…”

“…A major advance in valveless pumping was demonstrated by Stemme and Stemme (1993) who substituted check valves by nozzle/ diffuser elements with fluid-directing effects. Follow-up work by Olsson et al (1995) and Olsson (1998) on the realization of in-plane nozzle/diffuser elements triggered great interest in the field of microfluidics (Gerlach et al 1995;Gerlach 1998;Olsson et al 1999;Nguyen and Huang 2001;Pan et al 2003). Nozzle/diffuser micropumps are of particular interest for disposable lTAS applications because of the simple realization of the diffuser element that significantly lowers fabrication costs.…”

“…A large-stroke membrane deflection ($200 lm) is obtained using external electromagnet actuation. We present a detailed analysis of the magnetic actuation force and the frequency-dependent flow rate of the micropump and analyze our experimental data using the theoretical models of Olsson et al (1999) and Pan et al (2003).…”