Nanotechnology-Enabled Sensors

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Chapter 6: Inorganic Nanotechnology Enabled Sensors
Fig. 6.51 The schematic of a typical spin-dependent transport structures of a MTJ.
6.7.4 Other Nanotechnology Enabled Magnetic Sensors
Similar to many other effects, it is also possible to enhance the Barkhausen
effect (see Chap. 2) and use it for sensing applications. Vazquez
et al observed bi-stable magnetic behavior which they considered as a giant
Barkhausen jump. 131 This effect appears spontaneously in large magnetostriction
Fe-based wires and in nonmagnetostrictive Co-based wires
under particular thermal treatments. This effect can be also detected in micro-wires
as long as 2 mm exhibiting positive magnetostriction in its amorphous
state, as well as after transformation into nano or micro-crystalline
structures. The effect can be important for improving conventional bistable
materials for applications in various sensor devices, such as position
sensors, revolution counters, and magnetic codification systems.
Magnetic materials can also be used for gas sensing applications. For instance
Punnoose et al 132 demonstrated that a nanoscale magnetic hydrogen
sensor can be fabricated based on systematically varying the saturation
magnetization and remanence (remanence is the left behind magnetization
in a medium after removing an external magnetic field) of nanoscale anti-