A Dutch bitcoin entrepreneur has had two microchips containing the virtual currency injected into his hands to help him make contactless payments.
The chips, enclosed in a 2mm by 12mm capsule of "biocompatible" glass, were injected by a professional using a special syringe.
They emit a tiny radio signal using Near Field Communication (NFC) and can store up to 888 bits of information each.
"We wanted to do this experiment to push further the concept of the virtual wallet," Martijn Wismeijer, co-founder of MrBitcoin which installs bitcoin cash distributors, told AFP.
Using NFC, the chips can communicate with devices such as Android smartphones or tablets.
"What's stored on the microchips should be seen as a savings account," rather than a current account, Wismeijer said.
"The payment device remains the smartphone, but you transfer funds from the chips," said Wismeijer, who was injected with the chips along with a handful of other people on November 3.
His experiment has garnered so much publicity that he has temporarily withdrawn the money from his hands for security reasons.
"The aim wasn't for everyone to know about it," he said, laughing.
The chips are available on the Internet, sold with a syringe for $99 (around 80 euros) by the Dangerous Things company.
"It's really not recommended to do this yourself, you should find a specialist if you want to avoid infections," Wismeijer said.
Besides storing bitcoins, the chips can be programmed with a smartphone to do such things as open doors electronically or turn an alarm clock off if placed in a certain position.
Around 1,500 people around the world have already had such chips injected, Wismeijer said, but he did not know how many carried bitcoins.
Such experiments are important to make the technology acceptable to society, he said.
"Imagine having a tattoo that is normally invisible but turns red if you have a heart attack: you scan the tattoo with your smartphone and your doctor is immediately alerted."
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