Shear-strain sensors advance

Yuri M. Shkel (75K JPG)

Shear-strain sensors are needed in a variety of applications, such as tactile feel for robotics, remote hazardous materials handling, and detection of fluid flow. But many of today's shear-strain sensors are either limited in their applications, cannot be assembled in arrays, or are expensive to use.

Assistant Professor Yuri Shkel has developed a novel class of strain sensors that can be used for a variety of sensing needs. Shkel's strain sensors are aimed at sensing shear deformation in nearly any kind of dielectric — or nonconducting — material, such as plastics, organic polymers, resins, paints, clay materials and biological materials.

The sensor is a solid-state, single-plate device in which pairs of electrodes are positioned in close proximity to the material being measured. The strain sensors can then detect "electrostriction," essentially what occurs with dielectric properties when the material undergoes shear deformation.

Shearing strain, or deformation, is what occurs when material is attached to something and force is applied along the surface.

"There are many good methods to measure normal strain," Shkel says. "For shearing strain, it's not as easy to do. To design a sensor to measure shear strain is extremely challenging. It needs to be sensitive, yet tolerant to large forces."

Shkel says the new strain sensors can be made very small — 100 microns in size — and can be used on nearly any kind of dielectric material of any size, shape or characteristic. And because the technology behind the sensors is relatively simple, they could be manufactured at lower costs than current sensors.

"It's very simple," he says.