The humble tape measure is easy to take for granted, but it's a marvel of modern engineering. A 25-foot-long piece of spring steel, far less than 1mm thick, can be coiled into something that clips to a pocket. Unfurled, a curve is induced across its width, giving it a beam-like strength that allows it to hold a rigid, straight shape.

Researchers at the University of California San Diego found another application for tape measures beyond measuring: Being used as robot hands. Those companies currently developing humanoid robots will tell you that developing artificial human-like hands is expensive. The UCSD researchers reckon tape measures can accomplish a lot of gripping and conveying tasks at a fraction of the cost.

"We like to look for non-traditional, non-intuitive robot mechanisms," says Nick Gravish, an Assistant Professor at UCSD's Department of Mechanical and Aerospace Engineering. "The tape measure is such a wonderful structure because of its combined softness and stiffness together."

The gripper has two "fingers," made of two spools–each made of two rolls of measuring tape bound together. Each spool is rolled up, in a compact configuration, with only a small part extending out in a triangle shape to form a finger. These triangle sections are controlled by four motors each that control the finger's motion. Each finger can move independently. The triangle sections can lengthen to reach objects that are farther away. They can also retract to bring objects closer to the robot arm the gripper is mounted on.

The dual-conveyor-belt configuration means their invention, called GRIP-tape (Grasping and Rolling In-Plane), can rotate objects in place:

In a fruit-picking application pursued by the team, the two fingers can rotate a lemon to break it off at the stem:

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For now, the invention requires remote control. The team's next steps will be to add sensors and AI, in hopes of achieving autonomous function.