Velocity measurement of particles flowing in a microfluidic chip using Shah convolution Fourier transform detection

A noninvasive radiative technique, based on Shah convolution Fourier transf orm detection, for velocity measurement of particles in fluid flows in a mi crofluidic chip, is presented. It boasts a simpler instrumental setup and o ptical alignment than existing measurement methods and a wide dynamic range of velocities measurable. A glass-PDMS microchip with a layer of patterned Cr to provide multiple detection windows which are 40 mum wide and 70 mum apart is employed. The velocities of fluorescent microspheres, which were e lectrokinetically driven in the channel of the microfluidic chip, were dete rmined. re effects of increasing the number of detection windows and sampli ng period were investigated. This technique could have wide applications, r anging from the determination of the velocity of particles in pressure-driv en now to the measurement of electrophoretic mobilities of single biologica l cells.