Something that I had intended to try is to take one of the expended pads , soak it it a mosquito repellant , let it dry and seal it in a baggie . Then try it out to see if it works . You might be able to find the butane cartridges in drug stores , WalMart , etc where they have curling irons as some of the units use the butane cartridges for heat in the non electrical units .