In Dune, the shields were belts. In the Foundation series, they are worn as necklaces.
I can see a problem with shields in the possibility that they are not air permeable. This would limit the amount of time they would be usable, as the wearer would be limited to the air contained in the shield on activation. The air inside would also get stale more quickly if an impact to the shield occurs.
I can see a problem with shields in the possibility that they are not air permeable. This would limit the amount of time they would be usable, as the wearer would be limited to the air contained in the shield on activation. The air inside would also get stale more quickly if an impact to the shield occurs.