D4.2 - On-chip Biosensing with high-Q Amorphous Silicon Microdisk Resonators

T. Lipka, J. Amthor, H.K. Trieu & J. Müller
Low-loss hydrogenated amorphous silicon (a-Si:H) microdisk resonators which are employed as evanescent field refractive index sensors are presented. The resonances of the whispering gallery modes exhibit extinction ratios of >25dB and Q-factors ~10 4 in aqueous solutions. A sensitivity as high as >400nm/RIU was measured for NaCl-solved in DI-water. The resonators intrinsic limit of detection was calculated to be LOD=3.3x10 -4 and the minimum detectable amount of NaCl was experimentally determined to be 0.0375%. The...