Session: 16-01-01: Poster Session: NSF-Funded Research (Grad & Undergrad)

Paper Number: 88403

88403 - 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. Since thermal bubble-driven micro-pumps are based on thermal inkjet technology, the infrastructure to mass produce components with thousands of inertial pumps as well as associated microfluidics is readily available due to the commercial success of thermal inkjets by Hewlett-Packard. 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 its 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.

In this work, low-cost, rapid fabrication of thermal bubble-driven micro-pumps is achieved using laser cutting of thin films to form a single material thermal inkjet resistor and laminate materials to form the microfluidic channels. In this study, a commercial fiber and UV femtosecond laser are used and characterized for resistor and micro-channel fabrication. In contrast to standard semiconductor micro-fabrication workflows, our proposed non-fab fabrication approach reduces the turn around time from weeks/months to a matter of hours/days greatly accelerating R&D learning cycles. The ability to “fail fast and fail often,” enables rapid prototyping of inertial pump technology previously impossible. Furthermore, this non-fab fabrication process is used to prototype inertial focusing, a new unit fluid operation, used to hydrodynamically separate cells in micro-channels. High speed imaging is used to study the functionality of thermal bubble-driven micro-pumps. Unit fluid operations are needed in order to form more complex systems in direct analog to how NAND, NOR logic gates in electronics form the building blocks of more complex systems such as a multiplexor. In general, we envision thermal bubble-driven micro-pumps as a means to one day democratize microfluidics by bringing low-cost lab-on-a-chip devices to the masses.

Presenting Author: Brandon Hayes University of Colorado Boulder

Presenting Author Biography: Brandon is a PhD student at the University of Colorado Boulder in mechanical engineering. His research focus is on 3D printing, microfluidics, and thermal inkjet systems through theoretical, computational, and experimental analysis. Brandon is an NSF GRFP fellow and seeks to study and apply inertial pumps to new fields and applications.

Authors:

Brandon Hayes University of Colorado Boulder
Robert Maccurdy University of Colorado Boulder