Respiration monitoring based on magnetic induction using a single coil

Respiratory activity correlates with the conductivity distribution within the thorax. The change in conductivity can be monitored by impedance measurements based on eddy current induction without any need for contact between instrumentation and body. A system for magnetic induction measurements of the thorax using a single sensor-coil is presented. In contrast to most other known single coil respiration monitoring systems, the signal is amplitude and not frequency modulated. This renders the possibility of measuring with constant excitation frequencies.