Microfluidic device capable of sensing ultrafast chemiluminescence

Based on the principle of liquid core waveguide, a novel microfluidic device with micro-scale detection window capable of sensing flashlight emitted from rapid 1,1'-oxalyldi-4-methylimidazole (OD4MI) chemiluminescence (CL) reaction was fabricated. Light emitted from OD4MI CL reaction occurring in the micro-dimensional pentagonal detection window (length of each line segment: 900.0 mu m, depth: 50.0 mu m) of the microfluidic device with two inlets and one outlet was so bright that it was possible to take an image every 1/30 s at the optimal focusing distance (60 cm) using a commercial digital camera. Peaks obtained using a flow injection analysis (FIA) system with the micro-scale detection window and OD4MI CL detection show excellent resolution and reproducibility without any band-broadening observed in analytical devices having additional reaction channel(s) to measure light generated from slow CL reaction. Maximum height (H-max) and area (A) of peak, reproducibility and sensitivity observed in the FIA system with the microfluidic device and OD4MI CL detection depends on (1) the mole ratio between bis(2,4.6-trichlorophenyl) oxalate and 4-methyl imidazole yielding OD4MI, (2) the flow rate to mix OD4MI, H2O2 and 1-AP in the detection window of the microfludic device, and (3) H2O2 concentration. We obtained linear calibration Curves with wide dynamic ranges using H-max and A. The detection limit of 1-AP determined with H-max and A was as low as 0.05 fmole/injection (signal/background = 3.0). (c) 2009 Elsevier B.V. All rights reserved.