title: On-chip spectrophotometry for bioanalysis using microring resonators.
abstract: We measure optical absorption in color-producing enzymatic reactions for biochemical analysis with a microscale optofluidic device. Cavity-enhanced laser spectrophotometry is performed on analytes within a microfluidic channel at visible wavelengths with silicon nitride microring resonators of 100 µm radius and quality factor of ~180,000. The resonator transmission spectrum is analyzed to determine optical absorption with a detection limit of 0.12 cm(-1). The device can be used to detect the activity of individual enzymes in a few minutes within a 100 fL sensing volume. The high sensitivity, small footprint, and low analyte consumption make absorption-based microring resonators attractive for lab-on-a-chip applications.
authors.forename: Arthur
authors.initials: A
authors.lastname: Nitkowski
authors.forename: Antje
authors.initials: A
authors.lastname: Baeumner
authors.forename: Michal
authors.initials: M
authors.lastname: Lipson