Dual function sensor (DFS) is intended for concurrent measurements of temperature and magnetic fields in cryogenic applications. The DFS approach can also be applied to the problem in cryogenic thermometry of temperature measurements in high magnetic fields, since, by simultaneous, direct measurements of temperature and local magnetic field, it enables computational correction of the field effects on the thermometer.

The DFS consists of a Ge-on-GaAs film resistance thermometer and an InSb-on-GaAs film Hall-effect magnetic field sensor, which at constant current provides an output voltage proportional to magnetic field induction. These sensors are incorporated in a parallelepiped package, made from gold plated copper, sealed with epoxy. The dimensions of this package are 3.5 mm wide, 2.2 mm high and 10.1 mm long. The DFS has eight copper contact leads:- four leads for the resistance thermometer and four leads for the Hall-effect magnetic field sensor.

Two models of the DFS have been developed and produced for use in the 1.5 to 400 K (DFS-1) and 0.1 to 400 (DFS-2) temperature ranges.

Typical resistance and sensitivity (S=dR/dT) vs. temperature curves for DFS-1 and DFS-2 thermometers that are intended for operation in the 1.5 K to 400 K and 0.1 to 400 K temperature ranges, respectively

InSb-on-GaAs film Hall-effect magnetic field sensor characteristics

  Operating temperature range.........................................1 to 400 K
  Input resistance...........................................................10 to 20 Ohms
  Output resistance.........................................................15 to 30 Ohms
  Rated control current....................................................0.5 mA
  Magnetic sensitivity (at rated control current)..................5 to 6 mV/Tesla
  Zero field offset voltage (at rated control current)............0.1 mV (max.)
  Temperature coefficient of magnetic sensitivity................0.03 %/K (max.)

L I T E R A T U R E

 
1. V.F.Mitin, N.S.Boltovets, V.V.Kholevchuk, V.V.Basanets, E.V.Mitin, P.C.McDonald, F.Pavese. Dual function sensors for concurrent measurements of temperature and magnetic fields in cryogenic applications. Cryogenics, Vol. 48, pp. 413-416 (2008).



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