Performance of an integrated microfluidic chip and position sensitive APD for the detection of beta emitting probes in cell cultures

A new device has been developed that allows imaging of charged particle emitting probes in a microfluidic circuit using a position sensitive avalanche photodiode (PSAPD). Microfluidic chips are an emerging technology that have been used in applications such as the synthesis of new molecular probes and incubation of live cell cultures in microfluidic chambers. This new device works by direct contact of the PSAPD detector with the substrate layer of a microfluidic chip and provides 2- dimensional images of the distribution of beta emitting probes over time. The spatial resolution of the PSAPD detector for beta particle imaging was evaluated with ¹⁸F line sources. The FWHM was measured to be 0.4 mm at the center of the field of view. The sensitivity of the device for ¹⁸F beta particle detection was evaluated as a function of substrate thickness between the source and detector surface. One of the applications of this new detector system is for the imaging of live cell cultures in a microfluidic environment. Preliminary images have also been acquired showing the uptake of [¹⁸F]fluorodeoxyglucose ([¹⁸F]FDG) probes in live cells incubated in a microfluidic chamber. Images of [¹⁸F]FDG uptake were acquired with less than 200 incubated cells over a period of 3 days. An increase in cellular [¹⁸F]FDG uptake was also observed by increasing the time period between cell feeding and [¹⁸F]FDG incubation in the cell chamber.