ABSTRACT
Aimed at beta spectrometry and dosimetry for mixed beta-gamma fields, a Si-plastic scintillator coincidence beta-ray spectrometer has been developed. The spectrometer collects pure beta-ray spectra by rejecting the gamma-ray detection events through coincidence. Both pulse height and arrival time of each detection event were recorded in list mode by a compact digital processing system. Spectral measurements were carried out using mixed beta-gamma fields from 90Sr/90Y and 137Cs sources for various beta and gamma count rates to evaluate the system performance. Coincidence beta spectra were collected for four fixed beta count rates (7.3-241 cps) from 90Sr/90Y while the gamma count rate from 137Cs was varied from 500 to 8000 cps. The coincidence beta spectrum was stable and unperturbed by the gamma detection events for most measurements while notable perturbation was observed in the low energy region when the beta to gamma count ratio is very low.
ABSTRACT
Despite the wide use of cytometry for white blood cell classification, the performance of traditional cytometers in point-of-care testing remains to be improved. Microfluidic techniques have been shown with considerable potentials in the development of portable devices. Here we present a prototype of microfluidic cytometer which integrates a three-dimensional hydrodynamic focusing system and an on-chip optical system to count and classify white blood cells. By adjusting the flow speed of sheath flow and sample flow, the blood cells can be horizontally and vertically focused in the center of microchannel. Optical fibers and on-chip microlens are embedded for the excitation and detection of single-cell. The microfluidic chip was validated by classifying white blood cells from clinical blood samples.
