Investigations and control of biological and synthetic nanoscopic species in liquids at the ultimate resolution of single entity, are important in diverse fields such as biology, medicine, physics, chemistry and emerging field of nanorobotics. Progress made to date on trapping and/or manipulating nanoscopic objects includes methods that use permanently imposed force fields of various kinds, such as optical, electrical and magnetic forces, to counteract their inherent Brownian motion.
The unmet challenges are exemplified by the need for intense fields (possibly harmful to biological species), the lack of versatility in handling different operating conditions and the limited functionality in solutions of high ionic strength necessary for biological applications. In this presentation, I will demonstrate a novel concept of switchable electrokinetic nanovalving, without moving parts, to confine and guide single nano-objects, including macromolecules, with sizes down to around 10 nanometers, suspended in a liquid in a lab-on-chip environment1. Unlike in membrane-based pneumatic microfluidic valves, the proposed nanovalves are based on spatiotemporal tailoring of the potential energy landscape of nano-objects using an electric field, modulated collaboratively by wall nanotopography and by embedded electrodes in a nanochannel system. Such nanovalves constitute basic building blocks in nanofluidic systems, and can be potentially combined to construct arbitrarily complex chip-based nanofluidic devices. To this end, we combine independently addressable nanovalves to isolate single entities from an ensemble, and demonstrate their guiding, confining, releasing and sorting. We show on-demand motion control of single immunoglobulin G molecules, quantum dots, adenoviruses, lipid vesicles, dielectric and metallic particles, suspended in electrolytes with a broad range of ionic strengths, up to biological levels. Such systems can enable nanofluidic, large-scale integration and individual handling of multiple entities in applications ranging from single species characterization and screening to in-situ chemical or biochemical synthesis and precise drug delivery in a continuous lab-on-chip process. In addition to above, I will present the optical methods used for tracking the very fast movements of nanoscopic species, down to biological macromolecules, in liquids.
Figure 1. Illustration of the electrokinetic nanovalve composed of two nanoelectrodes (yellow) placed on either side of the channel constriction and the schematic of an adenovirus. The valve is actuated by applying a voltage between the electrodes, and, depending on the state of the valve (closed or open), the virus is prevented from passing through or is able to move through the valve.
- Eberle, P., Höller, C., Müller, P., Suomalainen, M., Greber, U. F., Eghlidi, H. & Poulikakos, D. Single entity resolution valving of nanoscopic species in liquids, Nature Nanotechnology (2018), DOI: 10.1038/s41565-018-0150-y
Biography: Dr. Hadi Eghlidi is a lecturer and group leader at the Chair of Thermodynamics at ETH Zurich, where he initiated and leads research on nano-optics and nanofluidics. Prior to that, he received his PhD in experimental nano-optics from ETH Zurich (2007-2011), and was a postdoctoral fellow at the Institute of Biochemistry and Laboratory of Thermodynamics in Emerging Technologies both at ETH Zurich (2011-2014). Dr. Eghlidi’s current research is in the area of plasmonic metasurfaces for miniature optics and quantum optics, and interdisciplinary areas of tracking and electrokinetic motion control of nanoscopic objects in liquid and the use of plasmonics for thermodynamic phase change applications. Dr. Eghlidi is the lecturer of a course on advanced optical methods in nanotechnology and a co-lecturer of a course on thermodynamics & energy conversion in micro- and nanoscale technologies. He supervised two completed PhD theses and one postdoctoral fellow, and is currently supervising three PhD students, and closely collaborating with other researchers at the Chair of Thermodynamics toward combining the fields of plasmonics and thermodynamics. The two latest research projects, which he supervised, are accepted for publication in Nature Nanotechnology and ACS Nano.