On-chip absorption measurements using an integrated waveguide.
Square hollow waveguides are used to integrate measurement of absorption with chip-based electrophoresis. The 50x50 microm liquid channel and 50x50 microm waveguide are etched as a negative pattern into a silicon master and replicated as a positive in poly-dimethylsiloxane (PDMS). The uniform refractive index of the chip prevents guiding by total internal reflection. Instead, light at 488 nm is guided by reflection at the air-PDMS interface. The waveguide has a 60% efficiency over a distance of 3.2 cm. Separation of fluorescein and the dye BODIPY is demonstrated. A detection limit (S/N=3) of 200 microM fluorescein is obtained using a 50 microm pathlength and a simple photocell detector.
Splawn
Bryan G
BG
Chemistry Department, 1393 Brown Laboratories, Purdue University, West Lafayette, IN 47907-1393, USA.
Lytle
Fred E
FE
D000042:Absorption; D001896:Boron Compounds; D002138:Calibration; D004129:Dimethylpolysiloxanes; D004563:Electrochemistry; D019075:Electrophoresis, Capillary / Q000295:instrumentation*; D004867:Equipment Design; D019793:Fluorescein; D005453:Fluorescence; D008855:Microscopy, Electron, Scanning; D008904:Miniaturization; D012031:Refractometry; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012825:Silicon
C095489:4,4-difluoro-4-bora-3a,4a-diaza-s-indacene; D001896:Boron Compounds; D004129:Dimethylpolysiloxanes; D019793:Fluorescein; D012825:Silicon