A system providing a sterile connection between a sensor probe and a fluid processing apparatus (e.g., a bioreactor) includes a first probe receiving element mountable to the fluid processing apparatus and a second probe receiving element having a gas-permeable contaminant barrier material and coupleable to the first probe receiving element. A sensor probe may be mounted to the second probe receiving element, with the combination being sterilized with a sterilant gas such as steam. Following such sterilization, connection between the first and second probe receiving elements is made through matable sterile couplings, and the probe is insertable through the coupled receiving elements to a position in fluid contact with the interior of the fluid processing apparatus.