Ancient Chinese used their thumbprints to sign documents and authorize payments. Now a technology company is targeting hip young people who want to pay by finger.

We've heard about letting your fingers do the walking, through the Yellow Pages, but now you can let your fingerprints do the paying, at least in some spots.

Pay-by-finger debit technology - a kind of biometric recognition linked to your bank account - is considered very hip by some young people.

The manufacturer of Live by Touch says it has 100,000 registered users in Shanghai and 5,000 retail venues, and more to come. Its target audience is young people who want to be cool and are open to new ideas and innovative technology.

After all, the ancient Chinese used their thumbprints to sign documents and contracts and authorize payments, so there may be more cultural receptiveness to biometric finger scanners than in the West.

It's just getting started, many retailers are unfamiliar with it and it's unlikely that prints will take the place of plastic. Still, it has its appeal: If you don't have enough cash and aren't carrying a debit or credit card, just use your finger. It could make purchases very easy, and retailers like that.

So far they are in some inexpensive restaurants, ice cream stories, convenience stores, cinemas, clothing stores and department stores.

One pay-by-finger wannabe is Jessica Zhao. She finishes dinner with friends at a popular Japanese buffet chain restaurant on Nanjing Road Pedestrian Mall. She asks to pay by fingerprint.

"Wow, you can do that in Shanghai?" Zhao is flattered that her friends think she is so cool. But the waitress says she has to pay at the counter because she can't take the print pay device to the table.

A little embarrassed, Zhao goes to the counter to find a machine like that for swiping cards - except there's a small square at the bottom for a print. The staff member says it could be taken to the table, as with a debit card, but the waiters are unfamiliar with it.

"That's because you're our first customer," one tells her.

"I really like the service because it's convenient and hip. In Japan, you can pay by cell phone, but now we can only use our fingerprints, the way our ancestors did," says Zhao.

But it's still so new that the service hasn't caught up with the technology.

Pay by finger, as it's commonly called, is a new technology for retail payment developed and promoted by Shanghai-based technology company Live by Touch. It came out in Shanghai at the end of 2007 when some convenience stories were equipped with the system.