Possibility to fly with the help of helium

Today I will present you at least an interesting idea, if not, even achievable.

It is a system consisting of several components (not too complicated), which will give you the opportunity to fly.
Helium is primarily needed in gaseous form. Secondly, there is a need for a system that is capable of heating and cooling the helium in a flexible tank (for example a textile material) that is sealed in such a way that it can be carried on the back of a person ( like a backpack).
This tank (or bag) is filled with helium and is surrounded by a plastic pipe (basically a flexible tube) to transport warm, cold, hot water as appropriate.
If we want to rise higher then we increase the temperature of the helium in the bag and if we want to come down, then we lower the temperature. Basically we float in the air, and we get the control exactly in the way we swim in the water and by adjusting the water temperature in the heating / cooling system.
What happens? I do not know!

If we increase the temperature of helium it decreases its density, which means that it floats in a gas with a higher density such as air. The higher the helium temperature, the higher the density difference between the two environments and thus we reach the performance of flying (floating).
It is very important to note that helium is flammable, so pay attention to how we regulate the temperature, a balance must be found between the height we want to rise, body weight and helium temperature so that the helium does not reach a too high  temperature.

Possibility to fly with the help of helium
CAREFUL! It's just a theory, I haven't tested it and it might not work!