如何通过PHP将数组转换为字符串

I sit in Excel with the following problem:

I have an array that can contain one or more measures (multiselection from user) I want to get this array and transform it into a string with some added PERL expressions. I want the resulting string to be written in another array.

Sample input (the array can store from 1 up to arround 200 values):

{"KPI","Parameters","Personnel costs", "Fixed costs", "Building costs"}

Desired output:

^KPI$|^Parameters$|^Personnel costs$|^Fixed costs$|^Building costs$

or just:

KPI$|^Parameters$|^Personnel costs$|^Fixed costs$|^Building costs

So far I have this and it doesn't work:

<?php
function transform ()
{  
    $s = activesheet();
    $awb = activeworkbook();
    $PickList = array($awb->names->item('lstMeasureEDN')->value);
    $String = implode("|",$PickList);   

setRange( 'rngAtoS', $String );
}
?>