The barcode on your badge is part of a lead retrieval system that allows you to share your contact information with exhibitors. With the lead retrieval system, an exhibitor asks to scan your badge as you visit the booth, capturing your contact information (address, and email) encoded on your badge. This allows exhibitors to send you information while the conference is still fresh in your mind.
Sharing of the information encoded in your badge is voluntary. Exhibitors can not read this information remotely without your knowledge.