Magnetic stripes are everywhere — on the backs of I-cards, credit cards and even some driver's licenses.

The U of I Employee's Credit Union makes and distributes between 40 and 50 new VISA cards monthly and handles around 400 transactions per day, said Vice President of Marketing and Member Services Greg Anderson.

But how does one go about making a plastic card, like the I-card, that can unlock doors, allow students in dining halls and withdraw money from ATMs?

It's all in the dark magnetic stripes, said University physics professor Mats Selen.

Elaine Schaufele works on the third floor of the Illini Union Bookstore making I-Cards for students.

On the cards there are two magnetic stripes on the back side. The broader stripe contains the student's card number, and the narrow stripe is writable for use in vending machines and copiers, said Schaufele.

The process for creating a card is completely computerized, said Schaufele.

First, she takes the student's picture using a digital camera positioned in front of a blue background. She then crops the picture using her computer so it will be centered on the card. Last, a machine about the size of a microwave writes information onto the magnetic stripes and prints all important information on the front.

It then spits out the finished I-Card in a procedure that takes about five minutes.

How does a person go about storing information on a magnetic stripe?

"Credit cards work very much like a cassette tape," said physics professor Lance Cooper. "The stripe is made up of very small nanoparticles of iron (III) oxide."

These particles are like tiny bar magnets with a north and south pole. The problem is, in the beginning they are all positioned in random directions. In order to make the card readable, the poles need to be lined up correctly, Cooper said.

Computers read a code of zeros and ones; therefore the tiny particles must be aligned to represent either a one or zero. By using a magnet, they can be oriented so their north poles are either facing up or down, Cooper said.

They are now "frozen in place and can be read in card readers," said Cooper.

A card reader is nothing more than a coil of wire that becomes affected by the changing direction of the magnetic fields on the stripe.

The machine reading the card uses a physics concept in which a change in magnetic field creates electricity. When the card is sliding through the reader, it "sees" the particles changing from north to south pole and vice versa, said Selen.

The electricity created by swiping the card changes direction—clockwise or counterclockwise depending on the directions on the magnets, Cooper said. A computer can then translate that into names, account numbers, University ID numbers, or anything else a card issuer would want stored.

Cooper said cards get ruined if they are near a strong magnet or the stripe gets scratched; this will move the particles out of position.

"We take students in to see a very powerful magnet in our lab, and they think we are trying to steal from them because we have to collect their wallets into a plastic bag before going inside," Cooper said.

After an I-card is created Schaufele checks it to make sure it can be read by computers. After she swipes it, a card number appears on her computer screen and she hands the card over to its new owner.