In the nanoworld, tiny particles of gold can operate like snow blowers, churning through surface layers of semiconductors to dig unerringly straight paths. This trenching capability, reported by scientists from NIST and IBM, is an important addition to "self-assembly" methods that researchers aim to harness for making useful devices. Applications include integrating lasers, sensors, and wave guides into lab-on-a-chip devices used for disease diagnosis and screening experimental materials/drugs.