Investigation of optimal NMR-on-a-chip sensor positions for monitoring physiological magnetic field changes

Motivation: NMR-based field probes have proven as alternative method for acquiring physiologically-related magnetic field changes. However, positioning of those might be challenging due to variations in breathing patterns and/or anatomy. Goal(s): The goal of this work is to investigate different sensor positions to find optimal positions for measuring respiratory- but also cardiac-related magnetic field changes. Approach: The NMR-on-a-chip sensor was positioned at 7 locations around the torso and the measurement results analysed with respect to the detectable physiological components. Results: Anterior locations at height of the diaphragm and the cranial parasternal positions appear most promising for mapping of the respiration and cardiac motion, respectively. Impact: In this work, different locations for contactless sensing of physiological motion with a NMR-on-a-chip sensor around the torso were investigated. It is shown that both contributions might be separated with either bandpass filtering or principal component analysis.