PowerShell File Watcher w/o PowerShell Eventing

FilePing.ps1

Param
(
 [Parameter()]
 [string]$FileDirectory,   
    
 [Parameter(Mandatory=$true)]
 [string]$FilePattern,
 
 [Parameter(Mandatory=$true)]
 [float]$PollingIntervalMin,
 
 [Parameter()]
 [scriptblock]$FileFoundAction
)

function PollFileDirectory()
{
    Write-Host 'Polling Directory: $FileDirectory  at $PollingIntervalMin minute Intervals.' -ForegroundColor Cyan;
    Write-Host 'Target Pattern: ' $FilePattern -ForegroundColor Cyan;
    $existingFileString = [string]::Empty;
    
    #Poll Directory Indefinitely
    while ($true)
    {
        #Wait for Duration equal to PollingInterval
        Start-Sleep -Milliseconds ($PollingIntervalMin * 60 * 1000)
        
        #Create tab separated list of files found in our directory. Also a cache for future reference.     
        $fileString=[string]::Empty
        ls $FileDirectory -Filter $FilePattern | %{$fileString = $fileString + ($_.Name+"`t")};
        
        foreach ($fileName in $fileString.Split("`t"))
        {
            #Check for new and non-empty FileName
            if ($existingFileString.Contains($fileName) -eq $false -and $fileName -ne [string]::Empty)
            {
                #File is New
                Write-Host ('Match Found:' + $fileName) -ForegroundColor Gray
                #Add File to ExistingFileString
                $existingFileString = ($existingFileString + $fileName + "`t");        
                #Invoke any ScriptBlocks on the File
                if($FileFoundAction -ne $null)
                {
                    [string]$path=[string]::Concat($FileDirectory,$fileName)
                    [object[]]$arguments = [string]$path
                    $session = New-PSSession
                    Invoke-Command  -ScriptBlock $FileFoundAction -Session $session -ArgumentList ($path) -AsJob
                }
            }
        }
    }
}

#Start Polling for New Files
PollFileDirectory

Don't use this in production rather go for a solution using FileSystemWatcher and Register-ObjectEvent.