Charged-coupled device (CCD) detectors for lab-on-A chip (LOC) optical analysis

Abstract

A critical element of any Lab-on-A-Chip (LOC) is a detector; among the many detection approaches, optical detection is very widely used for biodetection. One challenge for advancing the development of LOC for biodetection has been to enhance the portability and lower the cost for Point-of-Care diagnostics, which has the potential to enhance the quality of healthcare delivery for underserved populations and for global health. We describe a simple and relatively low cost charged-coupled device (CCD)-based detector that can be integrated with a conventional microtiter plate or a portable LOC assay for various optical detection modalities including fluorescence, chemiluminescence, densitometry, and colorimetric assays. In general, the portable battery-operated CCD-based detection system consists of four modules: (1) a cooled CCD digital camera to monitor light emission, (2) a LOC or microtiter plate to perform assays, (3) a light source to illuminate the assay (such as electroluminescence (EL) or light emitting diode (LED)), and (4) a portable computer to acquire and analyze images. The con fi guration of the fluorescence detector presented here was designed to measure fl uorogenic excitation at 490 nm and to monitor emission at 523 nm used for FITC detection. The LOC used for this detection system was fabricated with laminated object manufacturing (LOM) technology, and was designed to detection activity of botulinum neurotoxin serotype A (BoNT-A) using a fl uorogenic peptide substrate (SNAP-25) for botulinum neurotoxin serotype A (BoNT-A) labeled with FITC. The limit of detection (LOD) for the CCD detector is 0.5 nM (25 ng/ml). The portable system is small and is powered by a 12 V source. The modular detector was designed with easily interchangeable LEDs, ELs, fi lters, lenses, and LOC, and can be used and adapted for a wide variety of densitometry, fl orescence and colorimetric assays © Springer Science+Business Media, LLC 2013.