Temperatures taken in the realm of the tiny

Some materials can be self-thermometers at the nanoscale

Nanowire temperature diagram

HEATING UP  This diagram shows the range of temperatures along a nano-sized aluminum wire injected with electric current. The marked area in the bottom left is about 310 kelvins (37° Celsius); the marked area top right is about 390 kelvins, hotter than the boiling point of water.

M. Mecklenburg et al/Science

To take the temperature of very small things, scrap the thermometer.