This thesis presents a fabrication process for medical microfluidic devices that is performed with purely silicon microfabrication methods, which is a better option for mass-production than commonly used soft lithography. The fluids passing through the channels of a microfluidic device that is fabricated using this developed method can be observed through a thin layer of silicon dioxide and thus solving the problem of silicon being opaque to light. The new method also allows for addition of electronic sensors to the fabrication of the microfluidic devices. Using the developed microfabrication method mentioned above, a medical microfluidic device working with cell mechanobiology principles to test and develop medicine is designed and presented. The device first measures the transit time of a cell passing through a restriction section with a width smaller than the cell diameter. The cell then passes through a long serpentine channel where it is treated by a medicine that is under development. The medicine diffuses into the microchannels with diseased cells from another microchannel that is running parallel with the cell channels through a porous membrane. The cells pass through another restriction section after being treated and the transit time is measured again. Comparison of transit times before and after treatment is an indication of the effectiveness of the medicine being tested.