Imaging of chemiluminescent reactions in mesoscale silicon-glass microstructures

Chemiluminescent reactions in mesoscale analytical structures (chips) containing micrometre-sized interconnecting channels and chambers (pL-nL total volume) were imaged. The chips were fabricated by bonding Pyrex glass to etched pieces of silicon using a high-temperature diffusive bonding technique. In initial experiments light emission from an enhanced chemiluminescent horseradish peroxidase reaction and from a peroxyoxalate reaction contained in straight channels (300 microns wide x 20 mu deep; volume 70.2 nL) and open chambers (812 microns wide, 400 microns deep, 5.2 mm long) linked by channels (100 microns wide, 20 microns deep) to an exit and entry port were studied using a specially modified microplate holder and an Amerlite microplate luminometer. Light emission from more complex structures (two chambers interconnected by a branching channel 100 microns wide, 20 microns deep) filled with a solution containing alkaline phosphatase, Emerald, and CSPD was imaged using a Photometrics Star 1 CCD camera. Detailed investigation of the detection and spatial resolution of the signal was performed on a Berthold Luminograph LB 980 using both the enhanced chemiluminescent horseradish peroxidase reaction and a peroxyoxalate reaction. We successfully resolved light emission from silicon structures with dimensions 100 microns wide and 20 microns deep. These simple silicon structures served as models for more complex designs that will be used for simultaneous multi-analyte assays in which an imaging system resolves and quantitates light emission from different locations on a silicon-glass analytical device.