Novel Valveless Micro Suction Pump Using a Solid Chemical Propellant

Abstract

Recently, various micro injection pumps with different driving forces have been reported. However, attributed to the poor performance and reliability of valves in the micro scale, no micro suction pump has found a successful application thus far. In this paper, a valveless micro suction pump, using a solid chemical propellant, azobisisobutyronitrile (AIBN), is developed for the first time. This novel pump is designed based on the Bernoulli Principle applied to a Venturi tube. That is, for an incompressible fluid, a negative pressure is generated as the fluid is accelerated through a vena contracta section. In the designed pump, the width of the vena contracta section is 350 µm, and the width ratio of the input fluid inlet and the vena contracta section is approximately 8.5:1. The core of this pump is a propellant chamber with an AIBN matrix, which generates biologically inert N₂ gas as it is heated by an underlying micro heater. The generated gas passes through the Venturi tube producing a negative pressure at the front section of the vena contracta in the Venturi tube. The pump and channels are fabricated by curing polydimethylsiloxane (PDMS) on a silicon mold which was patterned using the deep RIE process. The micro pump is tested for sampling porcine gastric juice. Heating the AIBN core for 3 seconds successfully pumped approximately 20 µℓ of gastric juice, showing the pump’s potential applicability to various lab-on-a-chip devices and systems.