Abstract: An apparatus houses an intravascular sensor and is configured to measure the analyte in a biological sample of a host. The apparatus includes a fluid coupler having a first end configured to mate with a connecting end of a catheter and a second end configured to mate with a tubing assembly including, for example, an infusion pump, and a housing connected to the fluid coupler. The housing is configured to receive a sensor disposed within the fluid coupler such that when the fluid coupler is mated to the catheter, the sensor can be exposed to a biological sample. The housing is also configured to electrically couple the sensor with an external device, such as a processor for receiving and analyzing the sensor output. The housing and the fluid coupler are connected such that a fluidic seal is formed thereby preventing fluid in the fluid coupler from entering the housing.