Chip-Scale Whispering Gallery Mode Glass Shell Resonators for Calorimetric Biosensing Applications

In this work, we demonstrate high Q-factor chip-scale whispering gallery mode (WGM) glass microshell optical resonators thermally coupled to a microfluidic system as sensitive calorimetric biosensors. Optical resonance is induced in spherical borosilicate glass shell structures released from silicon substrate using tapered fiber and 1550 nm laser. Temperature change induced from highly selective enzymatic reactions induces thermal expansion and thermorefractive changes in the glass microshell resonators which manifest as changes in the optical resonance characteristics. As an initial proof of biosensing concept, urea-urease reaction is sensed using this system.