Micromachined flow cytometers with embedded etched optic fibers for optical detection

This paper presents a device that integrates a micromachined flow cytometer with two embedded etched optic fibers in order to carry out on-line detection of particles and cells. A simple and reliable fabrication process is used to fabricate the cytometer on soda-lime glass substrates. It is shown experimentally that particles/cells can be squeezed hydrodynamically into a narrow stream by two neighboring sheath flows such that they flow individually through a detection region. The resulting scattered light is then detected by etched optic fibers downstream. The proposed approach has the advantage that particles/cells can be counted without the need for fluorescent labeling or delicate optical alignment procedures. The current study confirms the success of the proposed microchip in the counting of polystyrene beads and human blood cells. The results also indicate that the intensity of the scattered light is proportional to the size of the particles/cells, which suggests that the proposed device may offer the potential to distinguish between particles/cells of different sizes.