Humanity’s most underrated sense is touch. Our ability to feel is so fine that if our fingers were the size of Earth, we could tell the difference between individual cars on the street. But now even our fifth sense is under siege from robots, as researchers in Beijing have developed a self-powered robot “skin” precise enough to sense a bee flying near it.

The technology is designed to work with prosthetic limbs, potentially reviving the ability to feel touch in those who have lost body arms and legs. And while it’s not the first model of robot skin developed, it uses a fourth of the number of electrodes as older versions, lowering costs, and does not require an exterior power source. The skin harvests the mechanical energy generated by the use of the prosthetic limb to power the four sensing electrodes.

The skin is actually just an ultra-thin plastic film and the electrodes tiny silver wires. Without the bulk of batteries or expense of more than a dozen electrodes, the new development appears poised to speed the commercialization of robotic touch sensors. Prosthetics offer a clear market, but the potential for robotic sensors go well beyond it as well.

The development of an advanced skin could help improve how robots move and sense their environments. It is no secret that despite their intelligence, robots still lag in many physical dimensions. The contradiction is the subject of the Moravec’s paradox, named for Hans Moravec, who wrote in The New York Times in 1988: “It is comparatively easy to make computers exhibit adult-level performance on intelligence tests or playing checkers, and difficult or impossible to give them the skills of a 1-year-old when it comes to perception and mobility.”

Wrapping robots in sensitive skins would help the bots sense their environment and in turn gain a better grasp of it. Humanoid robots in particular need to be able to match humans’ sense of touch, and lots of companies are looking for ways to improve their prototypes. So we should be careful. It seems our mastery of the physical world may be only skin-deep.