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 by Robert Freitas in Section 7.4.6.7 of Nanomedicine, Vol. I. In this first of four images, the user has activated her dermal screen by pressing the correct spot on the backside of her hand, causing the previously invisible screen to begin to power up, and become visible.