An extremely simple thermocouple made of a single layer of metal.

A novel temperature sensor consisting of a single layer of metal (Ni, Pd, W, or Pt) is constructed. Its configuration challenges a long-established concept and may lead to development of a new category of devices. Reliable two-dimensional mapping of local temperatures is demonstrated using an array of these sensors. These single-metal thermocouples (SMTCs) can be readily applied on flexible substrates or at high temperatures.