Sqlite in C# with REGEXP

I'm trying to build a search query to match whole words in SQLite and C# on Windows. When I run a query like this:

SELECT a, b FROM Events WHERE c REGEXP @SearchString;

Then:

cmd.Parameters.Add(new SQLiteParameter("@SearchString", 
"%[^a-zA-Z0-9]" + searchdata.SearchText + "[^a-zA-Z0-9]%"));

And when I call:

var r = cmd.ExecuteReader();

I get REGEXP no such function. I wonder how to activate REGEXP support and CASE SENSITIVE search.