Hi Doctor Emad in Egypt,
I have always believed that pain relief can be had by allowing the brain to concentrate on something else. This always works for guys, who can do only one thing at a time. Not for women, most can do many things at the same time.
Take an Asprin. Your brain will be concentrating on the damage that it is doing to your stomach, and you forget about the original pain.
Drop something heavy on your toe, etc.
Maybe you can make an electric device that uses infrared radiation to give a minor burn like a sunburn, that would probably give pain relief. I have never tried it. Can you feel heat that is radiated by a high-current IR LED? I can't feel anything from my low-power remote.