A Japanese medical company says it has built a prototype of the world's thinnest hypodermic needle, which at just 0.2 millimetres wide can slide into skin with almost no pain. A spokeswoman for Tokyo-based Terumo Co. said the company expects to have a commercially viable model ready in one or two years. Thinner needles are "less invasive, both physically and psychologically," said Joan Erickson, a nurse educator who works with diabetics in British Columbia. "The bigger the needle, the bigger the hole is what it boils down to ... smaller's better." The newly designed needle is just two-thirds as wide...