The solution is rather simple ..... a braile mark embossed into the surface which is easily incorporated into the manufacturing process.
I'm not sure this would be practical. Greenbacks tend to age rather quickly. They're more like cloth than paper.
That is because paper money is not actually paper, but a very, very, very fine linen. The way to go would be the Australian way, plastic paper money (they have had it since 1988!!!!!). It last a lot longer and if it gets wet it does not matter. If you used that method, embossing would probably last a lot longer than on paper. Also with plastic it would probably be possible to put a very slight wave in the thickness for example to aid identification without effecting the ability to fold he note.
Plastic moneyHowever, rather than go to another country and ask how it is done, we can instead spend billions researching the problem plus court costs from various interested parties and sending politicians on
holidays research and development trips funded by the tax payer.....us, just like the UK ID card instead of asking Germany, France or Holland how they do it. I have recently taken duel nationality, my ID card here is Germany,
"A bit of a pickle" - British translation: A catastrophically bad situation with potentially fatal consequences.
PETA

People Eating Tasty Animals.
B1 (Cat C) licenced engineer, Boeing 737NG 600/700/800/900 Airbus A318/19/20/21 and Dash8 Q-400
1. Captain, if the problem is not entered into the technical logbook.........then the aircraft does not have a problem.
2. And, if you have time to write the fault on a napkin and attach to it to the yoke.........you have time to write it in the tech log....see point 1.