A microfluidic device, a diagnostic device including the microfluidic device and a method for making the microfluidic device are provided. The microfluidic device includes: (i) a transparent substrate comprising a cavity, the cavity opening up to a top of the transparent substrate; (ii) a transparent layer covering the cavity, and (iii) a semiconductor substrate over the transparent layer and the transparent substrate, wherein the semiconductor substrate comprises a through hole overlaying the cavity and exposing the transparent layer.