Detection of Beta Particles in a Microfluidic Chip Using a Scintillator and CCD

A new device is being developed that will allow imaging of the distribution of charged particles in microfluidic circuits, using a scintillator, a lens and a charge coupled device (CCD). Microfluidic chips are an emerging technology that will facilitate the study of molecular processes in pico-liter levels in a finely controlled manner. The ability to quantify low amounts of radioactivity in a microfluidic chip will provide researchers with a platform to investigate molecular processes in a controlled in-vitro environment. The new detector system consists of a plastic scintillator, a C-mount compact lens, and a Sony ICX285AL interline-transfer CCD cooled with a Peltier device. A microfluidic chip filled with fluoro-deoxy-glucose (FDG) solution was coupled to a plastic scintillator and the set up was placed inside a light-tight box for imaging. Preliminary studies were performed to test the feasibility of using the scintillator-based CCD detector system for this application. The CCD performance parameters were characterized by the photon transfer curve. The camera gain constant and read-out noise were measured to be 0.746 e-/ADU (analog-to-digital unit) and 8 e-, respectively. The dark current was also investigated with different temperatures and binning factors. The spatial resolution was measured and line pairs of FDG in a microfluidic chip were discernable down to a 0.5 mm separation. The system was able to quantify the activity level reliably down to 5 nCi/mm².