Yes. They need a sand bath - not necessarily a sand area. I have this one from Rodipet - it was a bit extravagant but it works a treat (the half cover stops sand flying out of the cage) - it's a nice cool place for them to go as well, being ceramic. And just the right size for a robo. However, it's heavy so either needs to be supported underneath, or on a shelf. Mine's on a shelf. If it's just sat on the substrate, a robo could tunnel under it and it fall on them.
I'm not keen on too much sand in a cage somehow. It's hard enough finding safe sand generally.
RodipetŪ EasyClean Luxury Sand Bath
It's bigger than it looks on the photo - it has loads more space inside with our robo in it! Photo must be a particularly large robo (or a bad photoshopped robo!)