Is being forced to use a biometric time clock legal?

I work in Pennsylvania in a supermarket. Our company just told us today that we will now be using a biometric system for punching in and out. A number of us have objections and concerns about this because it feels like a lack of privacy. We were also told that, "If you want to get paid, you have to use this clock as of Sunday." Do we have any rights regarding punching in and out using such a machine? Also, most of us handle no money if that is a factor. I need an answer or a reliable source for an answer as soon as possible as by Sunday, my fellow employees and myself will be forced to submit to this latest new rule.