Palm scanning technology uses vein patterns that are difficult to replicate, but experts say fraudsters are always coming up with new ways to scam people. SINGAPORE: Hold your palm over a scanner for two seconds, then wait a few more for payment to be processed. That’s how some Visa employees have been paying for their coffee at a cafe near Tanjong Pagar. The Visa-Tencent pay-by-palm machine at the Alchemist 71 Robinson was set up in October, but for now, it's only available to selected