A comparative study of photonic transducers for lab-on-a-chip biosensors

Label-free photonic biosensors often utilize transducers that are sensitive to changes in refractive index. When biomolecules adhere to the sensor surface, the refractive index changes leading to a change in sensor response. A transducer needs a low limit of detection as well as the correct dynamic range for the analyte under study. Ring resonators and photonic-crystal based components are popular choices for photonic transduction elements. A photonic crystal ring resonator is evaluated by first obtaining characterization data of a simpler component, a regular ring resonator. This data is utilized for a finite element study of the photonic crystal component to determine the average thickness of the analyte layer. The component is then fabricated and simulation and characterization data are compared.