Devices, systems, and methods to determine volume reflux. In an exemplary embodiment of a device of the present disclosure, the device comprises an elongated body having a sufficient length so that a distal end of the elongated body can extend to a gastroesophageal junction of a person while a proximal end of the device, or a connector coupled thereto, is present at or distal to a throat of the person relative to the gastroesophageal junction, and a plurality of least ten electrodes positioned at known distances from one another along the elongated body, wherein two or more of the plurality of electrodes can excite an electric field, detect within the electric field, or excite and detect within the electric field, wherein the device is configured to obtain gastric/reflux bolus data at or near the gastroesophageal junction.
