Peter F Hamilton

Also referred to as "OCtattoo," organic circuitry is a Commonwealth technology that implants computer technology in its users, allowing them to communicate with the Unisphere, control machinery, and running an assistant program referred to as an "e-butler" or "u-shadow."

OCtattoos, as the name suggests, are tattooed onto individuals and can be visible or not at the user's discretion. The most striking use of OCtattoos in the series is by Gore Burnelli, who in order to maximize his control over his commercial empire, receives so many OCtattoos that his skin appears to be completely gold. Later in the series, many people execute similar functions with biononics.

When an individual undergoes rejuvenation, the OCtattoos are removed from the body and new ones are needed. These are susceptible to antibody attack but generally last for decades.

In 2015 first steps towards real-world OCtattoos were reported by researchers at the University of California, San Diego (UCSD), who developed sensor inks capable of monitoring blood sugar levels and detecting other problems such as toxic pollutants and nerve agents.