A system and method for interfacing non-sterile sensors to a sterile flow stream is disclosed. Typically, sensors cannot be sterilized in the same manner as other components of the flow stream. This results in complex processes to incorporate a sterilized sensor into a sterilized flow stream. By introducing a separation membrane, the desired sensor can be interfaced to the sterile flow stream. By doing so, the sensor need not be sterile, only sufficiently clean. The membrane separates the sterile environment within the flow stream from the sensor, while still permitting the sensor to function.