Fascinating development. That means much, much greater control over ink deposition.

No doubt a potential worry for currency producers. Inkjets that have control over the physical build up of ink structure would pose an even greater threat of counterfeiting.

No doubt mints can introduce countermeasures to detect such threats but I'd suggest this tech (if perfected) will likely be too good for humans to detect a forgery at a glance. Reckon machine readers will become the order of the day, that's if physical paper/plastic currency continues to exist.