preg_slipt

["Sichta Daniel" <Daniel.Sichta@xxxxxxxxxxx>]

Hi all !!!
 
I have string like this "1234567890"
 
I need to split this into array like this
a[0] = "12"
a[1] = "34" 
a[2] = "56" 
a[3] = "78" 
a[4] = "90"
 
I know that for this is preg_split, but I don't know the string patern
for split.
Thank you in advance !!
 

Dan