It’s called MintChip. From Hacker News:
Every MintChip has an ID, and every transaction is logged on both the sending and receiving device with the ID of the other device. This means that if someone takes your chip, they get a complete record of every transaction you’ve ever made. In other words, it’s not anonymous at all.
The details are vague, but tying cash to a ‘tamper-proof’ hardware seems like the wrong direction.

Jerry Brito is a senior research fellow at the Mercatus Center at George Mason University and director of its Technology Policy Program. He also serves as adjunct professor of law at GMU and is a regular contributor to TIME.com.