Send data form multiple sensors to PC via serial Connection C# form

To make it easy for people to help you please modify your post and use the code button </> so your code looks like this and is easy to copy to a text editor. See How to use the Forum

Your code is too long for me to study quickly without copying to a text editor.

If your problem is with your C# code then you should ask on a C# Forum. This Forum is for problems with Arduino code.

...R