Posted to News on 9th Apr 2010, 11:23
High-precision thermistors for low-temperature applications
Variohm-EuroSensor is supplying Measurement Specialties' epoxy NTC high-precision thermistors for use in equipment that automatically processes human tissue samples at cryogenic temperatures.
Thermo Fisher Scientific's Microm HM525 Cryostat is used in the preparation of tissue section slides for clinical analysis; tissue samples taken from biopsies and other surgical procedures are automatically frozen, sliced and disinfected, then stored for later laboratory examination. The process requires absolute precision, complete reliability and fast throughput to meet the demands of modern clinical investigations and, at the heart of the machine, Variohm-EuroSensor supplies high-reliability, ultra-small-bead, high-precision thermistors from Measurement Specialties to monitor chamber temperatures down to -55degC.
The cryostats' temperature control process uses the resistive output from the epoxy NTC thermistor to help maintain a constant temperature that is precisely matched to recommended sub-zero temperature ranges for different types of tissue sample. Temperature output accuracy from the thermistor across this -10 to -35degC critical temperature range must be with in +/-0.2degC. Furthermore, the thermistors' thermal time constant must be capable of tracking the rapid cryochamber response times necessary to guarantee fast sample processing throughput.
Thermo Fisher's HM525 cryostat is typical of the high-reliability temperature requirements for Measurement Specialities thermistor products, which are supplied and supported in the UK exclusively by Variohm-EuroSensor Ltd. These thermistors are used for demanding temperature control, monitoring and compensation applications across aerospace, deep space, subsea and many other areas where 'safety without doubt' is a critical prerequisite.
The Measurement Specialties thermistor range is characterised by its robust construction, miniature size and excellent stability. For this application Variohm adds value by supplying the thermistor in a stainless steel probe housing that simplifies assembly in the cryochamber. Measurement Specialities temperature sensors are also used in biomedical, automotive, instrumentation, HVAC, consumer industries and instrumentation applications.
