Chemical Money would require a sufficiently unique Identity, a communication channel, and at least rudimentary computational capabilities.

Microfluidic Reactors would do the job! https://managainstthemicrobes.substack.com/p/full-upload-of-our-podcast-with-michael

Forward to timecode 1:17:15

ID could be part derived part entropy, broadcast to the local WBAN and write-once to all receiving nanosensor non-volatile storage for later tap to “pay” 
https://m.primal.net/IFnX.jpg 

 Oh, holy smokes!