Thermoelectrics are easy-to-service, costeffective systems that encompass high cooling efficiency in small sizes. With a wide range of heat pumping capacities, Thermoelectric Modules (TEMs) and Thermoelectric Assemblies (TEAs) afford precise temperature control, making them the only effective thermal management solution for many medical laser applications.
Many medical laser applications have tight space constraints and low weight requirements, making thermoelectrics a better choice than compressor-based systems. In addition, the solid-state assemblies have higher reliability with fewer moving parts and require less maintenance, resulting in less downtime over the extended product life cycle.
Thermoelectrics offer the ability to cool down to well below room temperature, DC operation with reverse polarity to accommodate heating and cooling in one system, and are easily optimized to minimize vibration and noise. The units can also be customized to accommodate medical regulation standards put in place to minimize bacteria infections, surgical complications, and recovery time. All of these factors, as well as being environmentally friendly and with a low-cost of ownership, make thermoelectrics an excellent choice for medical laser applications.
Thermoelectric Assemblies (TEAs) are cooling and heating systems utilizing Thermoelectric Modules (TEMs) to transfer heat by air, liquid or conduction methods that include integrated temperature controls. TEAs remove the passive heat load generated by the ambient environment in order to stabilize the temperature of sensitive components used in medical lasers.
Thermoelectric Operation TEAs use TEMs to dissipate heat. TEMs are solid-state heat pumps that require a heat exchanger to dissipate heat utilizing the Peltier Effect. During operation, DC current flows through the TEM to create heat transfer and a temperature differential across the ceramic surfaces, causing one side of the TEM to be cold, while the other side is hot.
A single-stage TEM can achieve temperature differentials of up to 70°C and transfer heat at a rate of up to 150 watts. In order to increase the amount of heat pumping capacity, the TEM’s modular design allows for the use of multiple TEMs mounted side-by-side, which is called a TE Array. TEMs are composed of two ceramic substrates that serve as electrically insulating materials and house P-type and N-type semiconductor elements. Heat is absorbed at the cold junction by electrons as they pass from a low-energy level in the P-type element onto a higher energy level in the N-type element. At the hot junction, energy is expelled to a thermal sink as electrons move from a high-energy element to a lower-energy element.
Reversing the polarity changes the direction of heat transfer. TEMs are rated at maximum parameters (ΔTmax, Imax, Vmax, and Qmax) under no load conditions, with temperature control accuracy achieving ±0.01°C under steady-state conditions. TEMs can be used as power generators and create from 1 to 2 watts of energy per TEM.
They can cool to -100°C (6-stage) and pump up to 150 watts of heat, with higher heat pumping capacities achieved by wiring TEMs into an array. Their geometry can vary from 2x2 mm to 62x62 mm and are much more efficient in heating mode than resistant heaters. They also fit into tight geometric space constraints that cannot accommodate a much larger compressor-based system.