Design and Preliminary Experimental Investigation of a Capsule for Measuring the Small Intestine Contraction Pressure

A tethered pressure measurement capsule was developed for measuring the small intestine contraction pressure to assist in locating capsules within the gastrointestinal (GI) tract and quantifying the contact force between the capsule and the small intestine lumen. The capsule was calibrated statically and dynamically in depth-controlled water at body temperature (37-38 °C). In vitro tests were performed on an intestinal simulator to verify the measurement function of the capsule. To perform a preliminary evaluation of its pressure measuring capabilities, the capsule was tested at a single location in a live pig model. The pressure signal from the live animal test was analyzed in the time domain, and then, the empirical mode decomposition and fast Fourier transformation were applied to analyze the contraction pressure and ambient pressure in the frequency domain. The contraction rate was 9.4 to 11.0 times per minute. The peak value of the contraction pressure was 0.24 ± 0.05 kPa. The successful test of this prototype lays the groundwork for a future untethered, swallowable version of the capsule, which will be capable of measuring dynamic pressures while in transit.