Optothermal Marangoni convection and sensing at the nanoscale

Research Project, 2020 – 2024

Effective detection of biological nano-objects, such as biomacromolecules or virus particles, remains a key challenge in medical diagnostics and pharmaceutics, in spite of enormous progress in the development of a wide variety of ultrasensitive biosensors over the past two decades. One of the core problems is to effectively deliver the target analyte to the sensor at low concentrations. The standard approach is to combine the sensor with advanced microfluidics, but this comes at the expense of dramatically increased complexity and cost. In this project, we will instead explore the possibility to utilize opto-thermally driven Marangoni convection for effective delivery of analytes to surface-bound nanosensors. The Marangoni flow is induced by thermal surface tension gradients around nanometric gas bubbles that we generate by laser irradiation of resonant nanoparticles. Preliminary results show that we can generate record flow speeds on the order mm/sec at kHz dynamic rate using this methodology. This is likely to decrease target delivery time by several orders of magnitude compared to diffusive transport. The project involves advanced flow quantification based on holographic optical tweezers technology; state-of-the-art nanofabrication and electrodynamics optimization; and established methods for functionalization and analysis of label-free nanoplasmonic biosensors.