Abstract Dysfunction of the lower esophageal sphincter (LES) could result in various gastrointestinal disorders, the dominant of which is gastro-esophageal reflux disease (GERD). However, minimally-invasive technology for direct, long-term, ambulatory monitoring of the opening and the closing of the LES is lacking. This thesis aims at filling this void by presenting a novel, catheter-based acoustic interrogation device for real-time monitoring the motility dynamics of the LES. Two miniature microphones were positioned above the LES to assess a monofrequent sound signal generated by a micro-oscillator located below the LES. The dynamics of the opening and closing of the LES was correlated with the monitored sound signal dynamics. The device was first tested in-vitro on a custom-designed LES simulator. Measurements showed statistically significant Pearson correlation coefficients (p
