Monitoring shear stresses is increasingly important in the medical sector, where the sensors need to be unobtrusive, compact and flexible. A very thin and flexible sensor foil is presented based on the shear stress dependent coupling change of optical power between a laser and photodiode chip that were separated by a deformable sensing layer. These opto-electronic components were embedded in a very thin foil of only 40 mu m thick. The sensitivity and measurement range can be modified by selecting the material properties of the sensing layer. The sensor response showed to be reproducible and the influence of normal pressure on the sensor was very limited.