A Yule-Walker based, low-complexity voice activity detector is disclosed. Light from the light source is reflected from the surface being polished and the detector detects the reflected light. With this arrangement, the efficiency of exploitation of frequencies is improved. A channel is defined by the elongated body between the two lock-joints, the channel being sized for the placement of the tie. A method is also provided for forming a field effect transistor comprising a nano-component that has been doped using such a dopant.