Abstract: A peristaltic pumping mechanism is provided with a non-permeable peristaltic circuit comprising two strips of thin metal laser bonded at their edges to form a tube. In one embodiment, the non-permeable tubing takes the form of a continuous loop having input and output ports. In another embodiment, the tubing is open and generally U-shaped. In still another embodiment, a dual-tube circuit is provided, wherein a central, metal tube is disposed within an outer elastomeric tube having an inner diameter larger than the outer dimension of the metal tube. The elastomeric tube supports the metal tube only at the ends of the circuit, enabling the metal tube to “float” within the elastomeric tube.