In Sweden, the latest must-have gadget is small enough to be inserted under your skin. Thousands are having rice-sized RFID (radio frequency identification) microchips implanted into their hands. The chips let users make payments and gain access to homes, offices, gyms, and trains by swiping against digital readers. In fact, so many Swedes want the device that chip-making company Biohax International is having trouble keeping up with demand. But what about safety and privacy concerns? Experts say the chips are mostly protected from hackers, and Swedes tend to be less worried about sharing personal information than people in other countries. “Having different cards . . . verifying your identity to a bunch of different systems just doesn’t make sense,” Jowan Österlund, Biohax’s founder, told NPR. “Using a chip means that the hyper-connected surroundings that you live in every day can be streamlined.”