PRIVATE equity group YFM has invested £1.1m in Peratech, the North Yorkshire technology firm.It plans to use the cash to grow overseas sales and fund further research and development of its quantum tunnelling composite (QTC) technology.This touch sensitive technology enables devices such as mobile phones to incorporate very thin touch and pressure sensors.Philip Taysom, joint chief executive of the Richmond-based firm, said: "In these financially challenging times, it is a real testament to both the QTC technology and the tea......for the full story register now for free or login below...