Pulsatory Mixing of Laminar Flow Using Bubble-Driven Micro-Pumps

Y-shaped microfluidic channels have been built with Computer Numerical Control (CNC) and laser cutting manufacturing techniques. Fluid is delivered to each port via external syringe pumps. Each Y-shaped channel contains thermal inkjet (TIJ) resistors built using conventional microfabrication techniques. The resistors vaporize water and generate drive bubbles. This work focuses on utilizing TIJ technology as an active mixing technique in microfluidics. By varying the electrical firing frequency of the resistors, fluid was successfully mixed with an effective mixing length equal to the length of the TIJ resistor. As such, we demonstrate the use of TIJ resistors as a scalable, active mixing approach in microfluidics. A metric to characterize the extent of mixing using TIJ resistors was proposed and utilized. In addition, the fundamental framework of TIJ bubble dynamics with respects to mixing was assessed.