Nested Check Folder

Hi guys, I am developing an application, written in powershell. I stuck in a point. I am trying to do a nested check into a folder with script. I want to make a script that will check whether its a folder or not, then if it's a folder, it will do the check again until it finds no more folder

$sourceFolder ="\\frafile03.freus.net\nonGb"
$newNameHeader="baru"
$aclLists = @()
$a = $(Get-ChildItem -Force $sourceFolder)
$index=2    
foreach ($i in $a)
{
     $i.Name
    $aclLists += Get-Acl -path $sourceFolder\$i
}

thats my code, im really stuck. any help will be appriciated