Scientists from RWTH Aachen University’s Media Computing Group and Saarland University’s Informatics Campus have designed expressive, flexible on-skin tactile feedback interfaces that create several sensations when triggered. Known as Springlets, the thin and flexible stickers can be worn anywhere on the body, and offer up a host of applications, including social communications, physical guidance, VR gaming, health interfaces, and more.
Springlets can be fabricated in a wide range of sizes and styles, and feature six types of computer-generated patterns — pinching, pressing, directional stretching, pulling, dragging, and expanding, all with non-vibrating silent operation.
“Springlets’ soft and thin form factor allows them to be worn on soft and curved body locations, thanks to their silent operation, even near the head. Springlets can be cut into any shape or size, they can be combined in a single interface, and digitally controlled to generate spatial sensations of various force profiles.”
The secret to Springlets’ sorcery is shape memory alloy springs (SMAs), which in this case, are soft metal alloy mechanotactile actuator springs with end-effectors that contract when a current is introduced, and expand when the current is switched off. The Springlets are embedded between a layer of rubber-silicone and kinesiology tape similar to what athletes use to help protect muscles and joints.
The scientists state that Springlets can be manufactured quickly and with low costs, which seems apparent considering the materials are readily available. The tactile feedback stickers do have a drawback; as the SMAs have a tendency to suffer from low controllability and efficiency due to the heating and cooling rates when actuated. To remedy the issue, the team is designing a second generation of Springlets with a closed-loop feedback system that will enable them to control the driving current, which should help to extend their life significantly.