An easy fabricated, simple control and label-free micro-detection system was demonstrated in a PDMS chip and a new method to distinguish particle’ size in a FBG-FP cavity is exhibited. In our experiment, The period of FBG is 535.5 nm and the left and right length of the FBG is 5 mm and 3 mm, respectively. An amplified spontaneous emission (ASE) source with wavelength from 1528 nm to 1573 nm is coupled into the input fiber. The output signal is detected by an optical spectral analyzer (OSA, MS9740A) with a resolution of 0.03 nm. Two 25-μm particles pass through the cavity continuously and the flow rate is about 5 μL hr-1. The high-speed OSA clearly shows a rapid spectral change when a particle passes through the cavity
