Bio-mechanical tattoos are realistic, three-dimensional impressions of a robotic bio-realm beneath the skin. It's a 'tromp l'oeil', or 'trick of the eye', since the skin often appears to be peeled back to reveal what you're truly made of - an improbable (but somehow sublime) combination of mechanics and flesh. Where there should be a mess of blood and bone, tendons and sinew, we might see mechanical components - gears, tubes, and levers. Some say these titanium parts represent our hidden potential.
In popular culture, the biomechanical phenomenon is best represented by the Star Trek cyborgs, a cloned race known as Borgs. Where hoses, pipes and wires co-mingle with corporeal limbs and orifices, here we have biomechanics. Skilled tattoo artists can cleverly replicate this fiction (or science fiction) in two dimensions.
More popular with guys than gals, these biomechanical designs are usually inked over the body's most powerful musculature - the upper arms, calves, thighs, back, and sometimes the wrist. Traditionally, they're done in black and grey, which lends itself to the accepted notion of metal and robotics. But full colour better serves an 'interior life' composed of fanciful objects found therein, like butterflies, and 'the light' of our true nature.