Temperature sensing materials

Target gas Detection range Operating temperature Sensing material Fabrication technique Ref. 

TGA) and by emission quantum yield and emission lifetime measurements. This coordination polymer has a high emission quantum yield = 40 % for [Tb(hfa)3(dpbp)] at room temperature) and a temperature sensitivity over a wide temperature range of 200-500 K. The thermosensing dye composed of Tb(lll) and Eu(III) coordination polymers is expected to open up new fields in the molecular chemistry of temperature-sensing materials. 

Removal of liquid from phase that is a known thermal decomposition hazard ( strip-to-dryness ), i.e. liqiiid/solid level falls below temperature sensing device leading to overheating of thermally unstable material resulting in decomposition. 

A very recent example of the first case is presented by Vilaseca et al. [71] where an LTA coating on a micromachined sensor made the sensor much more selective to ethanol than methane. Moos et al. [72, 73] report H-ZSM5 NH3 sensor based on impedance spectroscopy using the zeolite as active sensing material. At elevated temperatures (>673 K) NH3 still adsorbs significantly in contrast to CO2, NO,... 

Iridium dioxide — Iridium oxide crystallizes in the rutile structure and is the best conductor among the transition metal oxides, exhibiting metallic conductivity at room temperature. This material has established itself as a well-known - pH sensing [i] and electrochromic [ii] material (- electrochromism) as well as a catalytic electrode in the production of chlorine and caustic [iii]. The oxide may be prepared thermally [iv] (e.g., by thermal decomposition of suitable precursors at temperatures between 300 and 500 °C to form a film on a substrate such as titanium) or by anodic electrodeposition [v]. 

Conventional humidity sensors of the electric resistance variable type use hydrocarbon polyelectrolyte as a moisture sensing material. Therefore, the sensors usually have insufficient heat resistance, and cannot be used at temperatures of 60°C or more. Another problem is that they deteriorate when in contact with cigarette smoke and oil contained in the air [64,65]. When the fluorinated pitch-deposited coating was breathed upon, the electrical resistance quickly decreased, but electrical resistance quickly recovered when this action was stopped. Then, how to develop a humidity sensor excelling in humidity response sensitivity, heat resistance and durability was attempted [66]. Two kinds of comb-like electrodes with different electrode gaps were made, and a thin film was formed on the surfaces by vacuum deposition of fluorinated pitch. The obtained fluorinated pitch sensors were left at rest in a thermostatic chamber, and electrical resistance was determined under the following conditions. 

The National Institutes of Standards and Technology (NIST, formerly the National Bureau of Standards (40)] sells a high-purity gallium standard in a Teflon and nylon container [Standard Reference Material (SRM) no. 1968] for use as a temperature standard. The melting point is 29.7 70 C and can be used to calibrate thermometers and other temperature-sensing devices. 

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