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Thin Film Thermometer MTFT
Measuring Highly Transient Temperatures

Application
Thin film thermometers consist on a ceramic substrate of zirconium oxide on which a thin film of nickel is deposited. This sensor is a magnitude more sensitive than our thermocouples. Temperature changes of only 0.1 K can be measured. The gauges can measure static to high transient surface temperatures with response times in the range of microseconds.
Due to the open metal film these sensors are quite sensitive but also delicate. Therefore for measurements in clean conditions and moderate heat fluxes the Thin Film Thermometer are recommended, whereas in harsh environmental conditions or high heat fluxes our Coaxial Thermocouples MCT is the better choice.
The MTFT are powered by a constant current source. The change of the film resistance leads to voltage changes proportional to the temperature change. The temperature change corresponds to

ΔT = (R – R0) / R · α

For transient temperature changes the Thin Film Thermometer is connected to our MFA 1000 Amplifier and power supply. This device has a bridge amplifier and offers constant current and voltage.
To mount the sensor we recommend gluing the gauge into the wall. Alternatively we provide a wall mount adapter for easy reuse. As an advantage to competitive thin film sensors we pass two platinum wires through the substrate soldered to the film. These embedded connections eliminate the challenge of connecting wires to the thin leads and makes the wall mount much easier. Further these two wires are extended with four cables, two for current supply, and two for measuring.

image
Thin Film Thermometer with connecting wires and cables

There are multiple applications for this type of sensor. The gauges are suitable for measuring constant temperature over time, but transient measurements e.g. testing wind tunnel models give their superior field of application, the change of cylinder wall temperature in a piston engine or for calculations of heat flux in a re-entry phase on a rocket model in a hypersonic wind tunnel.
In the case of measuring the re-entry simulation on the space shuttle Hermes, thin film thermometers were used on the surface of the delta wings, where smaller temperature changes were expected. Our thermocouples were used in the nose of the wing due to the very high heat flux, the higher mechanical stability and the adaptive sensor head to the curved surface.


Technical Data
Thin film material:Nickel
Substrate:Zirconium Oxide
Smallest measurable temp. change:0.1 K
Responds time:< 10 µs
Resistance:25 to 50 Ohm
Temperature Range:< 70°C for continuous operation
Sensitivity:α = 0.002 to 0.0025/K
p c k About 0.35 J/(K cm² √s )
Power supply:Constant current 7 – 10 mAh
Diameter:2.3 mm ± 0.1 mm
Length:3.3 mm
Calibration:Delivered calibrated by University Aachen
Periphery:The thin film thermometer needs a constant current source and an amplifier. The type of periphery depends on the application.
 
 
Ordering information
Article-No. 100-002-1:Thin Film Thermometer MTFT with soldered platinum wires


Images
Thin Film Thermometer with connecting wires and cables


Publication on Applications
Description-gauges
Olivier H., Grönig H.
Instrumentation Shock Wave Tunnel - ICIASF 1995
Dr. Müller Instruments
Hasengarten 35
61440 Oberursel
Germany

Tel.: +49 - 6172 - 380 37 27
Fax: +49 - 6172 - 177 077 4
Mobil: +49 - 171 - 431 9060
info@Mueller-Instruments.de