Magnetic sensors and actuators

Sensors and actuators have assisted human activity during the last decades. Among them, those based on magnetic technology have emerged as a powerful tool due to their low cost, simple structure, the availability of different magnetic materials, and the capacity of contactless detection favoring their application in hard-working environments.

In this sense, our group has developed its activity in the design of magnetic devices based on soft magnetic Co-Fe based amorphous alloys The soft magnetic behavior promotes at high enough frequencies (> 100 kHz → 10 MHz), the appearance of the Giant Magnetoimpedance effect (GMI), that is, the large variations of electrical impedance under an external magnetic field (magnetic sensors). An analogous effect called Giant Stress-impedance effect (GSI) is observed when mechanical stresses are applied to the samples permitting the design of magnetoelastic sensors. So, both effects were used for the design of novel sensors and actuators for different technological sectors:

• Magnetoelastic sensors: applied in agronomics for the monitorization of hydric state in plants (1), monitorization of variation in the dimensions of cylindrical pieces (2), determination of liquids flow (3), etc. 
  
  
  Image: Ribbon-based magnetoelastic sensor prototypes for the monitoring of: (1) cyclical variations of plant trunk diameter, (2) variation of dimensions of cylindrical pieces and (3) liquid flow.

• Magnetic sensors: non-contact position sensor applied in agronomics (4), detection of nanoparticles,  characterization of low-frequency vibrations in simple magnetic systems (5) and complex systems (electromagnetic vibrational harvesters, 6), etc.
  
  
  Image: Wire-based non-contact magnetic sensor prototypes for the monitoring of: (4) cyclical variations of plant trunk diameter and vibrations in (5) simple and complex (6) magnetic systems (electromagnetic vibrational energy harvesters).
   

Contact: Cristina Gómez Polo