get_user can’t read variable


I have this little routine to find the user_id based on a usermeta field..

$  scaleData = json_decode($  reading, TRUE); $  deviceid = $  scaleData["imei"]; echo $  deviceid; // check to confirm is working. Yup  $  WhoIsUser = get_users(   array(    'meta_key' => 'deviceid',    'meta_value' => '$  deviceid'  ) );  $  CurrentUser = $  WhoIsUser[0]->ID; echo $  CurrentUser; //returns nothing 

But if I switch ‘meta_value’ => 45455 (iow a known device number) it returns the ID no problem. I’ve tried both $ deviceid and ‘$ deviceid’ What am I missing?