Many pharmaceutical and life science assays require accurate and constant temperature control in order to acquire meaningful data. Moreover, kinetic measurements are extremely susceptible to variations in temperature, especially over long measurements. In order to provide accurate and precise temperature control, many researchers have discovered that Peltier-based devices provide a low maintenance, cost-effective and efficient alternative to traditional liquid thermostatted methods.
Peltier devices are small, solid-state devices that control temperature by transferring heat from one side of a Peltier block to the other using electrical energy. The Peltier effect was first observed in 1834 and occurs when an electrical current is passed through two different metals connected to each other at two Peltier junctions. The current facilitates a transfer of heat from one junction to the other. One junction cools while the other is heated, thus bringing one side of the Peltier block to the appropriate temperature. Varying the electrical current allows precise temperature control and rapid equilibration.
To run efficiently, Peltier devices require a heat dispersal system to remove heat that builds up during operation. Using forced air flow, instead of recirculating liquid, to dissipate the heat build-up, the Air-Cooled Peltier accessory provides scientists with a maintenance free solution by eliminating the laborious procedure of monitoring recirculating water levels and adding anti-freeze and anti-bacterial mixtures to a recirculating water system.
How a Peltier system achieves thermal equilibrium is also very important. The Thermo Scientific Peltier temperature control accessories use a high-performance ramping method that reaches the set point temperature rapidly. This method does not take the Peltier block temperature above the set point temperature. For example, if a Peltier block temperature of 37°C is required, this temperate will never be exceeded. Many samples, like biologicals, can unfold, denature, or be damaged by high temperatures, making this ramping methodology particularly useful.
Another important consideration for liquid temperature control is sample stirring. Built-in magnetic stirring helps maintain thermal equilibrium throughout the sample by eliminating thermal gradients within the cuvette.