RFID tags are affixed to vials used to store samples, such as biological samples stored in
liquid nitrogen dewars or mechanical freezers. In one set of embodiments, an RFID tag is inserted into a recess at the bottom of a
vial and held in place by an insert that engages with
vial structure. In another set of embodiments, the RFID tag is retained in the recess by directly engaging with the
vial structure and without using a separate insert. Mechanisms for keeping the insert and / or tag in place include tabs that gouge into the vial material, clips that allow the insert / tag to be inserted, but not removed, and holes in the side wall of the vial recess that receive tabs extending from the insert / tag. Tag-
insertion techniques enable tags to be affixed to vials either before or after
insertion of the sample, thereby enabling
retrofitting of existing sample-storing vials with tags.