In most respects it’s an everyday picture. A waiter stands by a young couple in a coffee bar with a handheld terminal, ready to take a routine digital payment. The man raises his wrist to the machine. But he’s not wearing a smartwatch or offering a contactless card. He’s completing the transaction using a microchip that sits permanently beneath the skin on his hand.

“I believe that one day implants will be as popular as payment cards,” says Wojciech Paprota, founder of London-based tech start-up Walletmor, who claims to have created the world’s first microchip implant for contactless payments. For the man buying the coffee, the benefits of such technology are seemingly limitless. “Unlike a standard payment card,” says Paprota, “it cannot end up in the wrong hands. It will not fall out of your wallet, and no one will take it from there. The implant cannot be scanned, photographed or hacked.” The passive device can be fitted under local anaesthetic and...