To measure ambient temperature from -35 C down to -200 C for some special applications like vaccine storage, laboratory facility... you should not use ATE probe, but using the other type sensors such as RTD or thermocouple.

I. When do you use the RTD sensors for Cryogenic applications?

Advantages of RTD sensors:

• Measure temperature over a wide and precise range.
• Diverse design, high durability, and many different sizes.
• Good electrical conductivity.
• High stability, low error (0.1%/year)

Disadvantages of RTD sensor: 

• The temperature range that can be measured is not as wide as a thermocouple, only -200°C to a maximum of 850°C is well felt.
• Slow heat response.

II. When do you use Thermocouples for Cryogenic applications?

• Meanwhile, the thermocouple can measure up to 1700°C with R or S thermocouple
• Faster thermal response than RTD sensor
• And measured continuously due to high-grade porcelain or 316L stainless steel construction and high Platinum composition, but the accuracy is not equal to RTD

That is why Thermocouple Sensors are often used in harsh industrial applications, can measure continuously with high frequency.

In summary:

III. After you got the right sensor, how can you connect it to an IoT system or an Automation system?

Wireless methods

For RTD Pt100 sensor

• The RTD Pt100 sensor can be connected to the Wireless Sub-GHz transmitter at this link: https://www.daviteq.com/en/?prd=_WS433-PT100_wireless-pt100-temperature-sensor
• The RTD Pt100 sensor can be connected to LoRaWAN device: https://www.daviteq.com/en/?prd=_WSLRW-PT100_lorawan-pt100-temperature-sensor
• The RTD Pt100 sensor can be connected to Sigfox device: https://www.daviteq.com/en/?prd=_WSSFC-PT100_sigfox-pt100-input-sensor

For Thermocouples sensor

• Thermocouple sensor can be connected to Wireless Sub-GHz transmitter: please contact us
• Thermocouple sensor can be connected to LoRaWAN device as this link: https://www.daviteq.com/en/?prd=_WSLRW-TCK_lorawan-thermocouple-type-k-temperature-sensor
• Thermocouple sensor can be connected to Sigfox device: please contact us

Wired methods

RTD or thermocouple can be connected to a transmitter that can deliver output 4-20mA or RS485 Modbus RTU. Please contact us for more details.