pH estimation of fetal scalp blood using magnetic induction spectroscopy technique

Abstract

This thesis describes the development of fetal scalp pH estimation utilizing magnetic induction spectroscopy technique. Magnetic induction spectroscopy is a non-invasive approach that applies a magnetic field to determine the passive electrical properties. The relationship of the induced signal at the receiver and fetal scalp pH value was investigated. COMSOL Multiphysics® software was used to simulated sensor probe design. The simulation was done with several parameters such as frequency range, sensor geometry, number of turns and distance between transmitter and receiver coil to determine the suitable single channel magnetic induction spectroscopy technique for fetal scalp pH measurement design. The best result from parameters simulation was combined and finalized to be final sensor design. Then, the hardware was develop according to the simulation result. Mathematical equation was derived to show the relationship between voltage and pH. The result shows that the magnetic induction spectroscopy was capable to detect pH changes in the fetal scalp blood mimic model. The frequency range must be in the range of MegaHertz to increase the production of induced field. Circular coil was choose as the most suitable sensor geometry due to its sensitivity to detect smallest hydrogen conductivity changes in fetal scalp blood mimic model. The distance between the sensing coils of 0.08 mm was better than 0.1 mm because the strength of the field decreases with increasing distance from the wire. The error percentage acquired from prediction mathematical equation was less than 1% and the correlation obtained between the induced signal and pH was greater than 0.9190.