Quantum Well Hall Effect Sensors for MPI/DPI inspections

The project is developing methods and electronic systems to detect flaws within a variety of materials, welds and components.
These Non Destructive Evaluation (NDE) technologies and methods are based on using advanced Quantum Well Hall Effect Sensors (QWHE) to detect minute changes in magnetic fields caused by defects within sample metals.
The potential scope of my research and the application of these sensors includes the development of portable handheld devices, automatic detection of defects using systems incorporated into the production line; as well as microstructure characterisation and reconstruction.
The intention of this research is to develop an industry focussed, accepted method of NDE, with the usability and simplicity of current methods (such as Magnetic Particle Inspection and Dye Penetrant) with the resolution and complex depth profiling that is offered by other NDE methods (such as Ultrasonic Testing), without the limits, restrictions and health impacts of Radiography.
Current research (February 2017 onwards) involves exploiting the characteristics of the QWHE sensor (high linearity and low noise at high frequencies) to use alternating magnetic fields of 50 Hz - 250 kHz to detect surface breaking defects as small at 1m (in length, width or depth).
Although Eddy Current Testing is a widely accepted electromagnetic method of NDE which is similar to our research, it uses coils to detect the magnetic field interactions caused by deviations in eddy current paths within a sample, caused by a defect.
Our research at high frequencies imitates this process; however, our QWHE sensors measure the direct interactions between eddy currents and the magnetic fields they produce, rather than detecting a secondary effect of impedance change in a detector coil. As such, our research is conceptually simpler and has the scope to give much more detailed defect characterisation.
In addition, the QWHE sensor detects the magnetic flux density whereas coils only detect the flux. As such, for coils to be sensitive at low-strength magnetic fields or at high frequencies, they have to be disproportionately large (in excess of 50 cm diameter to detect the flux). This restricts the portability of devices using these large coils as they are bulky and heavy. In comparison, the QWHE sensor is a semiconductor device which measures 3 mm and weighs less than 1 g.
In conclusion, the research potential using these sensors is huge, being able to test the use of arrays (phased, different orientations and integrated circuits) to further enhance the performance and capabilities of QWHE sensor NDE devices. Over the next few years I will develop these electronic devices, tailored to the needs of BAE Systems and industry parameters, with the intention of producing industry accepted instruments that can be used in real manufacturing and quality control settings.