import

@import works as a conventional CSS directive when:

A .scss or .sass file will be imported when:
If you wish to import a .scss file without generating the .css file for it, precede the filename with an underscore. An @import directive may import multiple files and be nested.
_color.scss:
.a {
  color: red;
}

margin.scss:
.b {
  margin: 0 auto;
}

.example {
   @import "color", "margin";
}

.example .a {
  color: red;
}
.example .b {
  margin: 0 auto;
}
It's not possible to dynamically import a Sass file based on a variable; interpolation is only for CSS imports. As such, it only works with url() imports.
$family: unquote("Droid+Sans");
@import url("http://fonts.googleapis.com/css?family=#{$family}");

@import url("http://fonts.googleapis.com/css?family=Droid+Sans");