How do Peltier refrigerators cool small objects without moving mechanical parts?

Peltier refrigerators cool small objects by utilizing the Peltier effect, a phenomenon where the flow of an electric current through a junction of dissimilar materials—typically n-type and p-type semiconductors—causes heat to be absorbed at one junction and released at the other.12

Because these devices rely on solid-state electron flow rather than traditional compression cycles, they function without any moving mechanical parts. In a typical configuration, multiple semiconductor thermocouples are connected electrically in series and thermally in parallel. When current is applied, a temperature difference develops between the junctions. By keeping the hotter junction cool through external heat removal, the colder junction can reach temperatures tens of degrees lower, effectively acting as a refrigerator.132

This technology is highly valued for its compact size and its ability to be regulated to maintain precise, stable temperatures, making it ideal for applications such as cooling samples on a microscope stage.12