You might have chipped your pet, but would you chip yourself?

Wellington man Ryan Wolstenholme has joined the "biohacker" or "grinder" craze that's picking up steam worldwide, merging man (or woman) and machine.

The Xero software developer implanted an RFID (radio frequency ID) chip into the webbing of his left hand.

He uses it to store his smartphone's address book. Hover your phone over his hand, and it offers to add him as a contact.

But the chip also supports the NFC (near-field communication) standard used for Paywave, so he hopes to one day use it for contactless payments too, or instead of a HOP card for tapping on to public transport.

Hover your phone Ryan Wolstenholme's hand, and his implanted chip will beam his contact details to it.

And he could also use it in lieu of his office swipe card, too, though his employer is not up for that at this point, for security reasons, and he understands that point of view. "If I wasn't flatting, I'd get it programmed for my door at home," he says.

Wolstenholme also has a Firefly 2 chip in his right forearm, for a cyborg-like glowing effect.

And he had a "Sensing Magnet" implanted in his left ring finger.

Why a magnet?

"It's strong enough to pick up at least four paperclips. It's fun to play with. It's like a sixth sense. It tingles in a magnetic field. I can sense my laptop fan, microwave and stovetop."

It might sound a bit of a playground effort to add superpowers, but for Wolstenholme it's about, "Understanding how your body works, and integrating technology with that. It's a form of personal expression. It's about ownership of your body. You can have the autonomy to add something to it."

Wolstenholme implanted the Firefly chip in his forearm in his flat, DIY style, using an injection kit designed for vets.

For his other two implants, he turned to Wellington tattoo parlour Flesh Wound, where a tattoo artist carved out a parcel of flesh, then "used a damp towel to gently push the chip into place".

In parts of the world, it's becoming quite the thing.

An RFID chip of the same size as the one implanted into Ryan Wolstenholme's hand.

NPR reports that somewhere north of 4000 people in Sweden now have microchips under their skin.

In the US, a software engineer caused a social media sensation this week after she took the chip off the card that opens her Tesla Model 3, then implanted it in her arm.

And the BBC recently profiled a man who has implanted a chip in his chest that gently vibrates when he faces north - making it a breeze to orientate himself when he uses Google Maps (although the Herald wonders whether it might not get a tad annoying at other times).

And Wolstenholme's tattoo artist, Flesh Wound's Hamish Halley, tells the Herald he's chipped around 10 people in Wellington. In case you're wondering, there's no anesthetic. It's a case of grin-and-bear-it, but Halley says "it's quick, like a piercing."

Wolstenholme says corrosion was an issue in the early days of the body-mod scene, but he, but not now.

Andrew Tabener, an associate professor with Auckland University's Bioengineering Institute, says while he's loathe to endorse amateur implants, they present no danger if done properly.

He notes cochlear implants routinely use implanted magnets to hold an external power supply in place.

And as for RFIDs, "Many people chip themselves, and have done so for more than a decade. Some magazines have even provided DIY instructions. It's safe if done properly with due attention to sterility and cleanliness - same as it is for your cat," he told the Herald.

But if you don't pay due attention, things could rapidly go south, warns Dr Greg O'Grady, who is with Auckland University's School of Medicine.

Ryan Wolstenholme points to his implanted RFID, and holds a syringe used for injecting chips. He paid a tattoo artist to carve out a small pocket of flesh, then nudge in the chip with a wet towel.

"Biohacking" these chips into humans seems to be getting plenty of attention. But it would be very unwise to implant anything experimental that is not biomedical grade, and amateur surgery is not a great idea at all," he said.

"The risks include serious infections, injuries and foreign-body reactions. The bar for medical devices to be cleared for human use is very high for implants - for a very good reason - and if a device has not cleared that process for human use, then it cannot be considered safe or smart to be doing it."

Last month, Facebook caused a stir by publishing a lengthy breakdown of its research into a brain-computer interface (or "BCI"), which is being carried out in partnership with the University of California.

The BCI programme's aim is to "let people type by simply imagining themselves talking", Facebook vice-president Andrew Bosworth said.

Initially, the technology is designed to help those who are neurologically damaged. But, ultimately, Facebook sees us using it for everyday social media.

If it does, expect the debate over Facebook privacy to get super-charged.

Would you accept a memory upgrade or other type of brain boost if the trade-off was that Mark Zuckerberg could potentially track your every thought and movement?

On a similar tack, last month Tesla and Space X founder Elon Musk revealed his latest venture is Neuralink - a "brain-machine interface" startup. Musk says Neuralink has developed "threads" that can be injected into the brain to detect neural activity.

The entrepreneur said unless we upgrade our brains using such hardware, artificial intelligence will leave us behind.

Wolstenholme, who has been following Musk's early efforts, says bring it on.

"The symbiosis of humans and technology is going to be an ever-increasing field as we work out how to make things smaller, and more compatible with the human body," he says.

But in the immediate future, his biohacking ambitions are more modest in scale.

He's thinking of inserting a Paywave chip in his arm.

And he might upgrade to a bigger sensing magnet.

"If I don't like it, it's easy to reverse with a scalpel," he says.