Electronic Arthritis Pain Reliever

  My idea is based on the simple electronic heating pad I frequently use at night for relief of the arthritis pain I experience often in my left arm. How often I have wished that...
  1.) The ends were sewn together to form a sleeve that my arm would fit into comfortabley and...
  2.) the pad was powered either by batteries (maybe convential aaa battieries or such... MAYBE watch style batteries since those last forever and/or was powered by a "recharge it during the day use it at night" type system... like a flashlight I have that always stays on the recharger... until I need it then I unplug it and use it). Either system for powering it would be better than plugging it into a wall where If I am wearing my 'Arthritis Pain Relief Sleeve' and fall asleep, turn over and as a result unplug it the heat goes off. If someone could invent this so I could eventually purchase one from Kmart or Wallmart I would be soooo appreciative.