Detection of Legionella Bacteria Using a Silicon-Based Photonic Microring Resonator Biosensor Enhanced by Dielectrophoresis.

Silicon-based photonic biosensors, such as microring resonators and Mach-Zehnder interferometers, offer label-free detection, high sensitivity, and full compatibility with semiconductor fabrication processes. Yet, the detection of living bacteria remains difficult due to the limited probability of cell binding on nanoscale waveguide surfaces. We present a microring resonator integrated with a nearby electrode that enables active cell transport via dielectrophoresis. Application of an alternating electric field concentrates cells within tens of micrometers of the sensing region, significantly enhancing detection efficiency. Using this approach, we demonstrate label-free detection of living Legionella bacteria. The method also enables future applications for distinguishing between live and dead cells, opening new possibilities for dynamic biological sensing.