Sensor introducer system, apparatus and method

An assembly including an introducer cannula and subcutaneous measurement device, and a method of its use. The device can form an aseptic seal to the introducer to resist passage of pathogens through the cannula. Insertion of the device into the introducer desirably causes a one-way coupling operable to force removal of the introducer and device as a single assembly. Installation of certain devices into certain introducers forms an electrical connection between an electrode carried by the introducer and system electronics. Desirably, the introducer provides a funnel-like structure operable to guide a device's probe tip into reception in the introducer's cannula.