First thing to know about finding the right detector is understanding the materials for sensing elements and wire materials for Resistance Temperature Detectors (RTDs) depends on the specific application requirements. Generally, the sensing element for RTDs is made of pure metals such as platinum, nickel, or copper, as they exhibit predictable and repeatable resistance changes with temperature.

For wire materials in RTDs, platinum is mostly used due to its excellent stability, accuracy, and wide temperature range. Platinum RTDs are probably the most popular and offer high accuracy and linearity over a broad temperature range.

Thermocouples, interestingly, utilize the Seebeck effect, where two dissimilar metals are joined together to create a temperature-dependent voltage. Different thermocouple types use different combinations of metals, and each type has a specific temperature range where it provides accurate measurements. Some common thermocouple types include Type K (chromel-alumel), Type J (iron-constantan), and Type T (copper-constantan).

Type K thermocouples are widely used and have a temperature range of approximately -200 to +1350 degrees Celsius. They are suitable for industrial applications due to their wide operating range and good accuracy.

As a specific example of an RTD, the platinum RTD (Pt100) is used a lot in various industries. It has a resistance of 100 ohms at 0 degrees Celsius and exhibits a predictable increase in resistance as the temperature rises. Pt100 RTDs offer high accuracy and stability, making them suitable for precise temperature measurements in industries such as pharmaceuticals, food processing, and HVAC systems.