Thermal Bubble-Driven Micro-Pumps: The Building Blocks to Bring Microfluidics to the Masses

Thermal bubble-driven micro-pumps (also known as inertial micro-pumps) are an upcoming micro-pump technology for moving fluid without the use of external pump sources. The ability to directly integrate such micro-pumps in micro/mesofluidic channels eliminates the need for large, bulky external syringe pumps as is common in most commercial micro/mesofluidic systems thus providing a means to truly enable “lab-on-a-chip” technologies. In general, thermal bubble-driven micro-pumps are high power thermal inkjet resistors. A current pulse heats up the surface of the resistor in microseconds causing vaporization of an interfacial fluid layer which forms a vapor bubble. This vapor bubble can then be harnessed to perform mechanical work. Inertial pumps can be thought of as the fluidic equivalent of a voltage source. One day, very-large-scale-integration of inertial pumps may enable complex fluidic operations similar to that seen today in modern electronics. Yet, thermal bubble-driven micro-pumps are still in their infancy. To date, few unit fluid operations have been demonstrated with this technology: namely only pumping, mixing, routing/sorting, and cell lysis. As such, this work focuses on (1) low-cost, rapid fabrication of thermal bubble-driven micro-pumps to accelerate learning cycles and increase accessibility and (2) prototype new unit fluid operations needed for lab-on-a-chip applications.