Several billion dermal display nanorobots residing in the epidermis of a human hand can be used as display screens to access real-time physiological information or other stored data, as described byĀ Robert FreitasĀ inĀ Section 7.4.6.7Ā ofĀ Nanomedicine, Vol. I. In this fourth of four images, the user has called up a stored personal image file on her activated dermal display screen and also decided to select a new fingernail color (instantly implemented) for herself.