A device for in vivo detecting and quantifying a concentration of an analyte in a peritoneal fluid of a subject. The device includes (a) a catheter having an open proximal end configured to be disposed external to the subject, an open distal end configured to be disposed within the peritoneal cavity comprising the peritoneal fluid, an anchor portion, an outer wall, and an inner wall, (b) a sensor disposed adjacent to the open distal end and configured to detect and quantify the concentration of the analyte in the peritoneal fluid, and (c) a main control unit disposed external to the subject, connected to the sensor via a wire, and configured to control the sensor, receive and store detection and quantification data from the sensor, and transmit the data to a second device. A portion of the wire is disposed between the inner wall and the outer wall of the catheter.
