Sticky memory may turn Post-it notes into flash drives

[Nipuna]

Slap a sticky note on your PC and instantly upload its contents. That's one possibility for a self-adhesive memory card designed for use in flexible gadgets.

Bendy memories have been made previously but they are hard to combine with other flexible electronics. To make a fully bendable device, parts must be layered, but manufacturing processes for such circuits use solvents that could dissolve the underlying components.

Yang-Fang Chen of the National Taiwan University in Taipei and his colleagues instead made a memory sticker, using a layer of graphene coated with conductive polymers and topped with aluminium electrodes. Graphene is a form of carbon just one atom thick with a variety of unusual properties, including a high van der Waals force. This type of natural adhesion is the result of the attractive or repulsive forces between molecules and is thought to help geckos stick to walls.

Wireless notes
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The team applied their memory sticker to a number of surfaces, including a business card and a medical wristband, and found it could retain data even when curved. The memory can also be stuck on a surface, peeled off and stuck to something else.

"I suppose there are some instances where you want to stick electronics on to something," says Mike Petty of Durham University. He thinks it is more likely that techniques will be developed to create flexible devices as a whole, rather than sticking parts together. But even in that case, upgraded versions of the memory device might be useful all on their own.

"Our memory is not only flexible but also transferable," says Chen. With the addition of a few more parts, such as a Wi-Fi radio, the device could act as a flexible flash-memory drive. "We think the idea might be realisable in future."

Journal reference: Advanced Functional Materials, DOI: 10.1002/adfm.201302246