Robots have been picking up parcels and parts in factories and warehouses for years. But they generally avoid humans in these situations, and they almost always work with consistently shaped objects in clutter-free environments. Life is far less structured for any robot that ventures beyond the factory floor. If such a machine ever hopes to work in homes or hospitals, it will need an advanced sense of touch capable of detecting nearby people and cherry-picking one item from an untidy collection of stuff.
These are difficult skills for a robot to learn. Traditionally, scientists avoided touch altogether, programming their machines to fail if they made contact with another object. But in the last five years or so, there have been significant advances in compliant designs and artificial skin. Compliance refers to a robot's level of flexibility. Highly flexible machines are more compliant; rigid machines are less so.
In 2013, Georgia Tech researchers built a robot arm with springs for joints, which enables the appendage to bend and interact with its environment more like a human arm. Next, they covered the whole thing in "skin" capable of sensing pressure or touch. Some robot skins contain interlocking hexagonal circuit boards, each carrying infrared sensors that can detect anything that comes closer than a centimeter. Others come equipped with electronic "fingerprints" -- raised and ridged surfaces that improve grip and facilitate signal processing.
Combine these high-tech arms with improved vision systems, and you get a robot that can offer a tender caress or reach into cabinets to select one item from a larger collection.