Acoustic Resonance for Microfluidic Flow Control

Operation of pressure-driven droplet-based microfluidics requires accurate control of multiple pressure inputs. Unfortunately, this level of control often comes at the expense of disproportionately large external control infrastructures, and cumbersome external fluidic connections. In an effort focused on moving toward self contained microfluidic systems, we have developed an acoustically driven pressure regulation concept capable of generating multiple independently tunable pneumatic output pressure signals from a single electronic input. The core components of the device are a resonance cavity and a flow rectification structure. The operational premise utilizes acoustic resonance i.e. the selective amplification of a specific frequency from a multi-tone signal, as a decoding platform for distributed pressure control. The flow rectification structure introduces a Reynolds number bias that serves to convert oscillatory resonance cavity pressure into useful positive gauge pressures. We present theoretical and experimental results to explain the central operating principles of the aforementioned components in addition to data obtained from macro scale prototypes. Finally, we discuss device scaling and incorporation into microfabracted systems.