The outer layer of skin cells on your finger does not detect anything. The outer layer of your skin contains cells that are dead. In fact, the outermost 25 to 30 cell layers of your skin consist of dead cells that do nothing beyond providing a physical barrier that keeps water in and chemicals out. Furthermore, all regular skin cells (keratinocytes), whether alive or dead, don't detect physical sensations since they are not designed to do this. Physical sensations that are experienced when touching an object are detected by special receptors that sit in lower layers of the skin. Such sensations include pressure, temperature, vibration, and skin stretching. Therefore, in order for you to detect a physical effect, it must first pass through all the layers of dead skin. For instance, in order for you to feel that a frying pan is hot, heat from the pan must travel through the outer layers of dead skin before it can reach the thermoreceptors nestled in the lower layers of the skin. The thermoreceptors then detect the heat and in response send an electrical signal along your nerves to your brain.