Computational Study of Compact Microring Resonator Biosensors for Label-Free Detection

High Q microcavities have been investigated for chemical/biological sensing due to their highly sensitive response to binding events. In this work, we design and simulate a feasible and near minimally sized microring resonator sensor with large enough sensitivity to detect a single cellular analyte. Sensor performance is evaluated by varying waveguide material and dimension, and light polarization and wavelength, to maximize the detectable resonant wavelength shift due to a single cellular analyte. 3D simulations using a finite-element based method show a 2.5 $\mu$ m radius sensor (approximately the length of one cell) produces a 125 pm wavelength shift, Q of 1150, and 6.4dB extinction ratio for a single bound cellular analyte, making the design promising for high sensitivity cellular sensing.