The embodiments disclosed herein relates to a system and method for calculating the velocity of a fluid in a channel by measuring optical refraction method. The system comprises a micro channel which has a reservoir on the top of it. Reagent or the fluid is kept 5 within the reservoir.

The fluid from the reservoir is allowed to flow through the micro channel. Light rays are made incident on the micro channel at different angles of incidence. The velocities at which the two incident angles refract normal to the channel are calculated using formula. From this, the velocity of the 10 fluid in the micro channel is calculated.