Three-dimensional elastomer bellows microfluidic pump

A key challenge for microfluidics is efficient pumping of fluids, which typically requires equipment that is significantly larger than the pumped fluid volume. This paper presents a miniature elastomer bellows pumps that can be integrated with a microfluidic cartridge. The bellows pump features three-dimensional geometries enabled by additive manufacturing in elastomer materials. To explore a large design space and investigate how pump performance depends upon geometry, we parameterized the design space, fabricated 146 pumps, and performed detailed characterization of pump mechanical properties and fluid-pumping performance. Mechanical property measurements of fluid-filled and unfilled pumps showed linear elastic (LE) stiffnesses from 0.15 to 6.4 MPa and critical stresses from 0.06 to 1.86 MPa. The pumps can deliver between 77 µL and 2.4 mL with a single stroke, and pump efficiency is between 54% and 92%, depending on the design. We explore the size, shape, and number of bellows features and the relationship between mechanical design parameters and pump performance. We find that the pumped volume mostly depends upon the radius and height of the bellows pump. Some pumps buckle under compression which limits the consistency of fluid delivery. The fluid-pumping performance strongly depends upon the bellows design and not on the geometry of the connected microchannels into which fluid is pumped. The research highlights opportunities for miniaturization and integration of microfluidic pumps, as well as opportunities for microfluidic components made from additively manufactured elastomers.