A startup company has developed a chipless radio frequency identification ink that it says has been successfully stamped on cattle and read from as much as 4 feet away.

The most common RFID systems, such as those used for toll-road passes or for tracking merchandise in warehouses, contain a chip and antenna. The process revealed by Somark Innovations last week uses an array of microneedles and an applicator with a one-time-use ink capsule to stamp an animal. The ink can be colored or invisible, and applied through fur.

The company sees a market for the passive RFID technology to track cows in order to reduce financial losses from cases of mad cow disease. Somark, formed in 2005 in St. Louis, is raising venture financing and hopes to license the technology for use with laboratory animals, dogs, and cats; for tracking prime cuts of meat; and even for tracking military personnel.

Ranchers might want an invisible stamp in order to make it more difficult for cattle thieves to tell which animals have been marked. Today, cattle are often tracked with ear tags.

Current chipless RFID systems include those with metal fibers embedded in paper and packaging materials. Other uses include tracking documents, preventing counterfeits, and creating "smart labels."

Co-founder Mark Pydynowski declines to say what is in its ink, except that it doesn't contain metals and is 100% biocompatible and chemically inert. That could let ranchers and meat buyers use stamps to verify that select cuts of meat originated in a hormone-free environment, Pydynowski says, adding that consumers would destroy the system by breaking down the ink when chewing the meat. That would prevent Big Brother from using a scanner to know whether someone ate a Big Mac or a filet mignon.

For people squeamish about the use of RFID, who worry about a tag on every item invading privacy, the digestibility of chipless RFID ink isn't likely to be enough to put their minds at ease.