[scientizscht (OP)]

If we have an acidic solution, this solution is positively charged overall?

And an alkaline, negatively charged overall?

[Bored chemist]

No.
Hydrochloric acid has as many chloride ions as hydrogen ions
The hydrogen ions are positive, but the chloride ions are negative.

[evan_au]

And an alkaline, negatively charged overall?

A typical alkaline solution would be produced by dissolving solid sodium hydroxide in water:
NaOH + H₂O = Na⁺ + OH^- + H₂O

The overall charge starts neutral on the left side, and ends up neutral on the right side.

[scientizscht (OP)]

What are the available sensors to detect acidity remotely?