Is your wallet the next relic of the digital age? Why pay with cash or plastic when you can use a smartphone?
That is what Ainsley Onstott did on a recent afternoon in Cambridge’s Kendall Square. She simply showed her iPhone to pay for a sandwich at Sebastians Cafe. “They scan it, and I get my receipt e-mailed to me,’’ said Onstott, 26, a special events manager at the American Heart Association.