<===> input.scss
$foo: 20px;
@media screen and ("min-width:#{$foo}") {
    .bar {
        width: 12px;
    }
}
@media screen and ("min-width:0") {
    .bar {
        width: 12px;
    }
}

<===> output.css
@media screen and (min-width:20px) {
  .bar {
    width: 12px;
  }
}
@media screen and (min-width:0) {
  .bar {
    width: 12px;
  }
}