Are injectable tracking devices even possible?

We often hear lately about nefarious plans involving injectable tracking devices... But is such a thing even possible? Given the current state of technology, would such a thing even work? Better yet, HOW would it work? After all, it's a long way from contactless payment cards to tracking chips floating inside inside millions of people who are constantly on the move. The answers to these questions surprised me - and they may surprise you, too!

Stuff mentioned in the vid:
- https://www.bichip.com/
- https://onlineweb.dkpto.dk/pvsonline/Patent?action=102&sagID=PA%202017%2000432
- http://www.nbcnews.com/id/17284751/ns/technology_and_science-innovation/t/hitachi-shows-worlds-smallest-rfid-chip/
- https://www.engadget.com/2006/02/06/hitachi-shows-off-7-5-micron-thick-mu-chip-rfid-tag/
- https://www.snopes.com/fact-check/smart-dust/
- https://rf-controls.com/passive-rtls-smart-antennas/
- https://www.rfidjournal.com/e-thread-provides-discrete-anti-counterfeiting-or-tracking-solutions

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