An array of bearing balls is attached to the gel of an optical tactile sensor, which captures the image of the gel from the opposite side. The sensor is pressed into a surface, pushing the bearing balls into the gel. An image is taken of the gel in this state, and is then processed to find the size of the circular imprints created by the bearing balls pressing into the gel. This size is compared to an expected value given the amount of force applied, and deviations from this value are noted as damage to the blade (protrusions or dents).