Applications of electroplated magnetic materials in sensors

Prof. W. G. Hurley,  Dr. Sai-Chun Tang 

Research objectives: Develop magnetic materials, processes, and techniques for the fabrication of integrated current sensors and demonstrate their use. To investigate the use of AMR (Anisotropic Magneto Resistance) and GMR (Giant Magneto Resistance) magnetoresistive sensors in automotive applications and demonstrate their use.

Many sensors, especially for proximity, speed sensing etc. are based on magnetic field detection principles because of their ability to provide a non-contact means of sensing. Almost all such sensors make use of magnetic materials, either as an integral part of the sensor (e.g. AMR, GMR, fluxgates), as a field concentrator or as a source of the field to be detected. At present, most of the discrete poison detectors use Hall sensors. Similarly many current sensing applications also make use of Hall sensors, which can be quite a bulky component because of their need for large magnetic cores to concentrate the field. Although these semiconductor sensors are cheap and can address today’s requirements, their potential is almost fully realised, their main disadvantages being, low sensitivity, piezoelectric effect and temperature drifts. Recent advances in magnetic sensor technology, e.g. GMR and AMR, sensors have allowed the miniaturisation and the improvement of the sensitivity of such devices. For example these developments can allow smaller less expensive magnets to be used in sensor systems and can facilitate the implementation of much smaller current sensors. This project will develop magnetic materials and processes for their deposition by electroplating. In particular the integration of these materials with MR based sensor systems will be investigated. The sensor systems to be investigated will include integrated current sensors and position sensors in automotive applications, e.g. geartooth sensing. The application of the materials and processes in novel senor systems will be demonstrated.

Start date: 1st of September 2001. This project has been completed.

Project Publications

Patent
M. Duffy, W. G. Hurley, P. Ripka, S.-C. Tang, "Excitation Circuit for a Fluxgate Sensor", NAT101/C/US, Patent No 6,867,587, March 2005.

Journal
S.-C. Tang, M. Duffy, P. Ripka, W. G. Hurley, "Excitation Circuit for Fluxgate Sensor Using Saturable Inductor", Sensors and Actuators A:Physical, vol. 113, no. 2, pp. 156-165, July 2004.

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