Patent ID: 7164849

Claim:
A vapor-emitting device comprising: a reservoir comprising a volatizable material; and an active end of use indicator in communication with said reservoir, wherein said active end of use indicator is configured to alert a user that said reservoir is at least one of substantially empty and includes an amount of volatizable material below a pre-determine level; said active end of use indicator comprising: a first electrode; a second electrode configured to contact said first electrode to form a completed circuit; and a material associated with said completed circuit, wherein: said material is configured to swell when in contact with said volatizable material and to contract when not in contact with said volatizable material; said completed circuit is disrupted when said material is in a substantially swollen state and said completed circuit is not disrupted when said material is not in said substantially swollen state; and said active end of use indicator is configured to actuate when said completed circuit is not disrupted.