Al is high conductive metal, so the heater current will flow in it. 1st you should oxidize the Al surface, 2nd you can deposit the heating element on the oxide surface. Screen printing is best method for such purpose.

To the above, I just want to add that controlled oxidation of the aluminum surface can be done either by anodizing or micro arc oxidation:

https://www.youtube.com/watch?v=0yl35W0o9S0

https://en.wikipedia.org/wiki/Plasma_electrolytic_oxidation

Dear Dr. Lokesh Kulhari ,

I suggest you to have a look at the Datec web site.

As said at this source, Datec is leading the industry with the unique ability to print heating elements directly onto aluminum, offering a seamless fit into a wide-range of product footprints and a thin, low-profile design. IntegrAL® heating technology produces fast, precise, uniform, and integrated heat to meet the demand for performance, reliability, and energy efficiency.

Available at: https://dateccoating.com/solutions/substrate-aluminum/

My best regards, Pierluigi Traverso.