In various examples, a feedthrough seal apparatus is configured to seal an opening in a device. The device includes a case surrounding an interior space, the case including the opening therein to allow access to the interior space from an exterior of the case. The feedthrough seal apparatus includes a plug disposed within the opening of the case. The plug is formed from at least one of a polymeric material and an adhesive material. The lead wire extends through the plug, such that a first end of the lead wire is disposed within the interior space of the case and a second end extends from the plug to the exterior of the case. The plug is configured to electrically insulate the lead wire from the case. Some examples include a method of making the feedthrough seal apparatus.