Electrokinetic Separation and Droplet Generation Realized in Conventional Microfabricated and 3D Printed Microfluidic Devices

Description:
Microfluidic devices have been used for numerous analytical applications with some of the most successful realizations achieved through the development of separation mechanisms based on electrokinetic phenomena. Over the past years, there has been interest in exploiting dielectrophoresis (DEP) as an additional physical mechanism to achieve separations, based on the dielectric properties of biological analytes and their surrounding medium and the resultant analyte migration in an inhomogeneous electric field. DEP has been applied for a variety of analyses including cells, and recently also for subcellular organelles and vesicles. We have developed insulator-based DEP (iDEP) devices and demonstrated approaches that induce ratchet-like migration for effective separation of sub-µm particles including mitochondria. Our iDEP developments have also included manipulation and separation with biomolecules, such as DNA and proteins. The latter remains a challenging task due to the extremely high electric fields required and limitations due to traditional lithography approaches used for the fabrication of iDEP devices. We have therefore explored high resolution 3D-printing and could demonstrate the successful iDEP manipulation of ferritin and phycocyanin. In addition, we used high-resolution 3D-printing to design microfluidic droplet generators. We developed suitable methodology to integrate electrodes in 3D-printed devices and demonstrated the use of electrowetting effects to stimulate droplet generation with externally applied potentials. This approach allowed us to design droplet generators for serial crystallography with X-ray free electron lasers (XFEL), where droplets laden with protein crystals in their mother liquor are generated and their arrival at the X-ray interaction point is synchronized with the pulsed XFEL. We have demonstrated this approach to reduce sample waste by >60% for serial crystallography with proteins both at the European and the Stanford XFEL.

Speaker: Alexandra Ros - Arizona State University
Dr. Alexandra Ros is Professor in the School of Molecular Sciences and faculty member of the Center for Applied Structural Discovery at the Biodesign Institute at Arizona State University. She received her PhD from the Swiss Federal Institute of Technology in Lausanne (EPFL), Switzerland, and her Habilitation in Experimental Physics from Bielefeld University. Dr. Ros joined Arizona State University in 2008 as Assistant Professor where she was promoted to Professor in 2020. She is recipient of an NSF Career Award, a Fellowship for Experienced Researchers from the Alexander-von-Humboldt Foundation, Germany, the FACSS Innovation Award and the AES Midcareer Award. Dr. Ros’ current research interests include migration mechanisms in the micro- and nanoenvironment for biomolecules and sub-cellular species with a focus on electrokinetic methods, hyphenation of analytical approaches for single cell analysis, and developing microfluidic tools for emerging crystallography techniques.