How to read subscript/superscript using PHPExcel library?

if ($objPHPExcel->getActiveSheet()->getCell($cell)->getValue() instanceof PHPExcel_RichText)
{
// $plaintext = $objPHPExcel->getActiveSheet()->getCell($cell)->getValue()->getPlainText();

$cellValueAsString = '';
$elements = $objPHPExcel->getActiveSheet()->getCell($cell)->getValue()->getRichTextElements();
foreach ($elements as $element) {
// Rich text start?
if ($element instanceof PHPExcel_RichText_Run) {
if ($element->getFont()->getSuperScript()) {
$cellValueAsString .= '^{';
} else if ($element->getFont()->getSubScript()) {
$cellValueAsString .= '_{';
}
}
// Convert UTF8 data to PCDATA
$cellText = $element->getText();
$cellValueAsString .= htmlspecialchars($cellText);
if ($element instanceof PHPExcel_RichText_Run) {
if ($element->getFont()->getSuperScript()) {
$cellValueAsString .= '}}';
} else if ($element->getFont()->getSubScript()) {
$cellValueAsString .= '';
}
}
}
echo $cellValueAsString;