Chip Scale Optical Microresonator Sensors Integrated With Embedded Thin Film Photodetectors on Electrowetting Digital Microfluidics Platforms

Miniaturized, portable, sensitive, and low cost sensing systems are important for medical and environmental diagnostic and monitoring applications. Chip scale integrated photonic sensing systems that combine optical, electrical, and fluidic functions are especially attractive for sensing applications due to the high sensitivity of optical sensors, the small form-factor of chip scale systems, and the low-cost processing possible for systems fabricated with well-developed mass production techniques. In this paper, a chip scale sensing system, which is composed of a planar integrated optical microdisk resonator and a thin film InGaAs photodetector, is integrated with a digital microfluidic system. This system was designed, fabricated, and experimentally characterized by dispensing and moving droplets of glucose solution from the reservoir to the microresonator sensor. The optical output of the resonator was transduced by the integrated photodetector to an electrical current signal for readout.