Studies on a micropump based on evaporation and capillary effects

An inexpensive micropump based on evaporation and capillary effects was developed. It was characterized by simple design, small dimensions, stable and adjustable flow rate during long working periods. The pump was composed of a water reservoir, liquid storage tube, water absorbing membrane, and evaporation apertures. Factors affecting the flow rate of the micropump were studied and discussed. The pump provideds steady flow rate in the mu L/min range within a working day under most ambient temperature and humidity conditions. The flow rate of the pump can be adjusted by changing the area of the evaporation aperture, and/or by using a blower. The flow rate precision of the pump is better than 3% RSD under most conditions.