University students in Boston have come up with a novel answer to the problem of always having to search for your public transit pass — a ring you can wear that you load up with different cash amounts.

The Sesame Ring is the brainchild of undergraduates at MIT and its partner college, the Singapore University of Technology and Design. It’s a kind of wearable technology that functions much like a smart card. The Sesame Ring is waterproof and can be loaded with money, using radio-frequency identification (RFID) chips to transfer data.

Simple to use, the ring is put on your finger and its flat "face" is placed against the scanner of a turnstile or any entry way, allowing the user to get through.

The Massachusetts Bay Transportation Authority (MBTA) in Boston has approved its use after a period of development that began in January.

In addition, the ring can be customized to the user's finger as well as colour preference. Currently, the ring’s body can be black, white, yellow, orange, red or blue while its face can either be gold or silver

"3D printing allows us to customize ring faces that identifies with target users," Edward Tiong, one of the creators, told Boston.com.

"We’ve also developed a sleeker design and a more effective assembly method that would make sense for mass production."

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Students at the Singapore University of Technology and Design were given the rings back in April to test out. They were used to access classrooms, laboratories and other campus facilities. (Sesame Ring/Kickstarter)

Tiong and his team, which includes designer Olivia Seow and business adviser Chris Benson, are trying to raise $5,000 US on the crowd-funding site Kickstarter, in order to fulfil their first set of orders.

Anyone can pledge $20 US to reserve a ring with a signature Sesame Ring face or pay an extra $30 US to customize the face.

The team says they’d like to have the rings in regular use by December this year on Boston’s trains.

The ring has big potential as it can essentially replace security cards.

Some 300 students at the Singapore University of Technology and Design were given the rings back in April. The rings, marked with the university logo, were used to access classrooms, laboratories and other campus facilities.