Design and development of bilayer sensor systems for biomedical and automotive applications

• Main Author: Katranas, George Spyridon
• Published: Cardiff University 2006
• Subjects: 610.28
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.583805

This investigation concerned the design and development of a novel measurement system that incorporates bilayer sensors for monitoring applications in the biomedical and automotive industry. The bilayer sensors are made primarily from a configuration of soft magnetic material on a non magnetic substrate that is used to enhance the changes in the relative permeability of the material, caused by tensile or compressive stresses. Three modulation techniques were examined as a method for convening the sensor signal information this is the first use of the phase (PM) and frequency (FM) modulation methods in conjunction with bilayer sensors. The measurement system incorporated, in software code, a range of mathematical concepts used for extracting and processing the sensor information signal. The use of simulated and acquired modulation signals allowed the comparison of the modulation techniques. Optimisation of the bilayer sensor was considered by studying the effects of the bilayer sensor physical dimensions and parameters on its performance. Also the thermal stability of the bilayer sensor and FM system was examined. Physiological measurements for the detection and monitoring of cardio respiratory activities were conducted. A bilayer sensor measurement system was used for the first time not only to detect but also to map the normal heartbeat rate through the hemo-dynamics of the carotid artery. The system was used to monitor a range of respiratory activities such as normal respiration, deep inhalation/exhalation and apnoea. The application of the sensor is a non-invasive and a non-disturbing method for monitoring biomedical activities related to skin curvature changes. The bilayer sensor measurement system was used for monitoring of airflow in turbulent conditions. Measurements were conducted for a variety of airflows and at a range of distances from the centre of the tube, were the flow is at maximum. Furthermore the effect of substrate thickness and material choice was investigated on the performance of the sensor. This investigation led to the design and construction of a novel measurement system than can successfully detect and quantify displacements in the micron range. The application of this system to biomedical and automotive applications showed the universality and adaptability of the bilayer sensors and its measurement method.