Ultrahigh Q Polymer Microring Resonators for Biosensing Applications

The capability of an ultrahigh Q polymer microring resonator as a biosensing system is systematically investigated. By optimizing the device design and fabrication process, the device operates in the slightly under-coupled regime with a record intrinsic Q factor of 8.0 × 10
⁵
, which offers a high sensitivity and low detection limit. In surface mass detection, a surface mass density of 12.7 pg/mm
²
of bovine serum albumin is detected due to the physical adsorption. The noise-equivalent detection limit is approximately 5.3 pg/mm
²
in a wavelength-shift scheme and 55.9 fg/mm
²
in an intensity-variation scheme. These results show that the best sensing performance with the on-chip polymer ring resonator system is achieved.