One of the biggest challenges in robotics engineering is mimicking the human sense of touch. The ability to respond to texture and pressure is essential for delicate tasks, such as surgery. To that end, researchers have developed a new type of sensor that has a tactile sensitivity comparable to that of human fingertips--making it 50 times more sensitive than previously existing technology.

The device, a so-called electroluminescent thin film, glows in response to applied pressure. The result is a finely detailed image of the texture of any object that touches the film. Designers Vivek Maheshwari and Ravi Saraf of the University of Nebraska-Lincoln demonstrated this effect by pressing a penny against the device (see image). Because the sensor produces data in the form of an optical image, the data can be quickly and easily collected by simply photographing the image. This represents a major step forward in the ease and efficiency of collecting information from tactile sensors. Quick data collection is critical to performing real-time tasks, for example grasping a tool with a robotic arm. If the tool starts to slip, the image produced by the electroluminescent film immediately shows the tool's motion, and the robots grip can then be adjusted to prevent it from falling.

The novel technology, described in today's issue of Science, also offers an advantage over earlier ones because it is self-assembled. The thin film consists of layers of gold and semiconducting nanoparticles that are produced out of solution, so the sensor can be built to conform to complex shapes, such as those on robotic appendages or surgical instruments. "You ultimately have to make a device on a very curved surface, like a cylinder, or an endoscope. Most of the existing technologies are too rigid; they won't bend that far," Saraf says.

The next step for this technology, according to Saraf, is to try to use its sensitivity to discern cancer cells from normal cells during surgery. By "feeling" tissue with the sensor, a surgeon may one day be able to differentiate and remove only diseased cells, leaving healthy tissue intact. In the future, it may also be possible to use similar technology to detect temperature as well as pressure, leading to improvements in the resolution of infrared cameras and ultrasound scans.