Faculté des sciences

Evaporation based micro pump integrated into a scanning force microscope probe

Heuck, F. ; Hug, T. ; Akiyama, Terunobu ; Frederix, P. L. T. M. ; Engel, A. ; Meister, André ; Heinzelmann, Harry ; de Rooij, Nicolaas F. ; Staufer, Urs

In: Microelectronic Engineering, 2008, vol. 85, no. 5-6, p. 1302-1305

A micro pump was integrated into a scanning force microscope probe for circulating liquid through its hollow cantilever and tip. The interior cross section of the cantilever was 2.25 μm × 3.75 μm. All fluidic parts were made of SiO2, while the tip apex was made of Si3N4. The key fabrication techniques were silicon wafer bonding and wet-oxidation. The pumping... Plus

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    Summary
    A micro pump was integrated into a scanning force microscope probe for circulating liquid through its hollow cantilever and tip. The interior cross section of the cantilever was 2.25 μm × 3.75 μm. All fluidic parts were made of SiO2, while the tip apex was made of Si3N4. The key fabrication techniques were silicon wafer bonding and wet-oxidation. The pumping mechanism was relying on the enhanced evaporation at an enlarged water/air interface at the exit of the microchannel. Capillary forces continuously wetted this interfacial area, thus drawing the liquid through the system. At room temperature, a pump rate of 11 pl s−1 was experimentally evaluated. The observed temperature dependence of the pump rate could be qualitatively understood by a plain model calculation.