Cryogenic temperature sensors

Here, Quantum Design UK and Ireland is focusing on Lake Shore Cryotronics' temperature sensors, summarising their performance and features. For the full summaries and sensitivity/resistance graphs, click and download the Temperature Sensor Selection Guide. 

Download the Temperature Sensor selection guide 

PT-100 platinum resistance thermometers (PRTs) are an excellent choice for use as cryogenic temperature sensing and control elements in the range from 30 to 873K (-243 to 600°C). Across this temperature span, PRTs offer high repeatability and almost constant sensitivity (dR/dT).

Cernox® 

Specifically designed by Lake Shore for the demanding requirements of cryogenic applications, Cernox thin film RTD sensors offer extremely consistent high-resolution measurements over a wide temperature range. Due to the materials used and the physical structure of the chip, Cernox sensors are inherently resistant to magnetic-field induced offsets and damage by ionising radiation. This makes Cernox a suitable choice for any traditional cryostat system. Cernox Page

Silicon diodes 

Silicon diodes are an excellent general purpose sensor with a wide operating temperature range, from 1.4 to 500K. With their adherence to a standard curve, silicon diodes are interchangeable. This makes them less complicated to operate and maintain. Silicon diodes have excellent accuracy and resolution below 30K, making them an outstanding choice below these temperatures. Above 30K their sensitivity is reduced. Due to orientation dependent magnetic offsets and a high susceptibility to ionising radiation, silicon diodes are only suitable for purely cryogenic environments. A number of mounting options are available for the silicon diode package. This gives the user flexibility in attaching the sensor to the optimal measurement location of a given experiment or environment. Silicon Diodes Page

Lake Shore can match sensors to read within 0.1K of each other at liquid nitrogen temperatures 

GaAlAs 

Gallium aluminium arsenide (GaAlAs) diode cryogenic temperature sensors lack the standard curve and interchangeability attributed to silicon diodes, however, they are particularly well suited for low to moderate magnetic field applications at low temperatures. Being a single junction direct band-gap device, GaAlAs sensors are effective in moderate magnetic fields up to 5T. Though sensitivity is poor above 50K, the GaAlAs sensing element exhibits high sensitivity (dV/dT) at low temperatures and a wide useful temperature range of 1.4 to 500K. Cernox or silicon diodes would be preferable in most setups. However, in magnetic field-enabled systems with maximum temperatures above 420K, GaAlAs sensors may be the best choice. Gallium Aluminium

Rox™ 

The Rox family are all ruthenium-oxide RTDs, but have quite different characteristics. In general, these are low-temperature sensors with useful maximum temperatures of 40K or less. Most Rox™ sensors are consistent enough to be considered interchangeable, with two accuracy bands available with each sensor model. Rox sensors are not suited for environments with ionizing radiation and also experience measurement shifts when exposed to magnetic fields, though these shifts can be compensated for. Four different Rox sensors are offered, each of them with different attributes suited to varied but specific environments and applications. Of the Rox models available, the RX-102 A is the most popular due to their interchangeability, low price, and sensitivity at liquid helium temperatures Rox Page

Platinum 

Platinum resistance thermometers (PRTs) are very popular due to their low price and are useful in higher temperature systems with operating ranges from liquid nitrogen temperatures (77.35K) to many hundreds of degrees Celsius, the only sensor capable of reading higher being thermocouples. Lake Shore’s 100 Ω PRTs adhere to the ISO standard temperature curve but have also been characterised for viable operation down to 14K. Above 70K, PRTs offer high repeatability and nearly constant sensitivity (dR/dT). Platinum resistors are also useful in magnetic field environments where errors approaching one degree can be tolerated. The physical material used in PRTs withstands ionising radiation. Users may trade accuracy for price with PRTs as they can be purchased fully calibrated, partially calibrated, or uncalibrated. Platinum Page

Lake Shore can also offer non-magnetic packaging options, namely, the PT-102 and PT-103 variants of the sensors  

The company uses controlled-purity platinum sensors, ensuring uniformity between devices from one device to another. 

Learn more

Simplifying large-scale cryogenic temperature measurement

The 240 Series offers a convenient, modular input solution for precision monitoring of cryogenic temperature sensors in large-scale applications employing distributed PLC-based control.

Further Reading:

• More about the 240 Series
• Native fieldbus integration
• Built-in temperature conversion
• Simplifying sensor excitation 

Discover the Lake Shore 240 Series

Lake Shore Cryotronics is represented in the UK and Ireland by Quantum Design UK and Ireland. If you have any questions, please contact Josh Hook ([email protected]), who would be delighted to run through your applications and requirements. For further information, email [email protected] or visit:www.qd-uki.co.uk