With the growing demand for lab-on-a-chip devices each year, it is critical that resources be invested into the development of new and improved microstructures that are capable of moving and manipulating fluids in a controlled manner throughout these devices. Micropumps and microvalves are the structures that perform these operations, and are critical components to overall device performance. For this work, successful fabrication of a robust peristaltic micropump was performed. The performance of this micropump demonstrates it has great potential for integration into a variety of instrumental and microfluidic device platforms.

Fabrication of this micropump was performed using soft lithography techniques. A novel fabrication approach was used for construction of the microchannels. In brief, PDMS is cured over a raised structure, created by molding aluminum foil over a 75 µm diameter wire preadhered to a glass substrate. The resulting microchannel cross-sectional geometries have a rounded, Gaussian curve-like shape, and thus are ideal for complete valve shutoff. A membrane of thickness ~125 µm seals the channel from the outside world. Actuation of the micropump is achieved with piezoelectric cantilever motors. Adhered to the tip of these motors are precision machined aluminum edge masses that serve as valves for the micropump. When three signals with different phases are sent to the cantilevers, a wave-like motion creates a net flow of fluid through the device.

A substantial amount of characterization data for this micropump will be presented. The dynamic range for flow rates in this device is large, ranging from ~50-320 nL/minute. Different flow characteristics were observed depending on the phase of the input signal delivered to each of the respective cantilever motors. Net pumping of fluid occurs against backpressures recorded as high as 36,759 Pa, using an electronic pressure sensor. Valve performance data for this device will also be presented, including valve closing/opening characteristics and valve leakage. This micropump was developed for inline integration of a direct sampling probe with online capillary electrophoresis analysis, for the purpose of studying neurochemistry in rodent brains. Current efforts are underway to optimize this micropump before being fully integrated into the online capillary electrophoresis instrument.