PROBLEM: Large pressures can induce detrimental deformation in micro- and nano-fluidic channels. Although this has been extensively studied for systems driven by pressure and/or capillary forces, deflection in electrokinetic systems due to internal pressure gradients caused by non-uniform electric fields has not been widely explored
NOVEL APPROACH: Finite electric double layers within nanofluidic channels can further complicate the physics involved in the deformation process. In order to design devices and experimental procedures that avoid issues resulting from such deformation, it is imperative to be able to predict deformation for given system parameters. In this work, we numerically investigate pressures resulting from a step change in conductivity and/or surface charge in micro- and nanofluidic channels with both thin and thick double layers.
FINDINGS: We show an explicit relation of pressure dependence on concentration ratio and electric double layer thickness. Furthermore, we develop a numerical model to predict deformation in such systems and use the model to unearth trends in deformation for various electric double layer thicknesses and both glass and PDMS on glass channels. Our work is particularly impactful for the development and design of micro- and nanofluidic-based devices with gradients in surface charge and/or conductivity, fundamental study of electrokinetic-based cavitation, and other systems that exploit non-uniform electric fields.
The Pennathur Laboratory focuses on understanding and exploiting fundamental micro- and nanoscale phenomenon and coupled physics at the solid-liquid interface towards real-world applications in medical diagnostics, therapeutics, and energy. We specialize in the fields of MEMS, electrokinetics, electrochemistry, microfluidics and nanofluidics, utilizing theory, numerical simulations and well-defined experiments to reveal and exploit coupled physics within microdevices.
When her daughter was diagnosed with T1D in five years ago, Dr. Pennathur envisioned new ways to apply her research to T1D treatment. She has proposed a painless, minimally invasive micro-needle “patch” for continuous glucose monitoring (CGM) applications.