In traditional robot designs, different tasks are relegated to different components. For example, a rigid rod may serve the function of a limb or finger. A separate motor will cause the rod to move. And sensors placed at the tips or hinges provide feedback about position and pressure, which is helpful when trying to manipulate objects. But this approach is so complex and cumbersome compared with the human body. Bones and muscles and nerves are all packaged in the same object, creating a compact and efficient device.

That’s the goal of researchers at Harvard’s Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) and the Wyss Institute for Biologically Inspired Engineering. They have created a soft robotic actuator that is fabricated using 3D printing. The new development is that they can incorporate sensor material as part of the 3D printing process. Using special ionic conductive inks, they can print flexible sensors inside the soft device. The sensors can measure both pressure and temperature. Different layers of sensors provide different degrees of touch sensitivity. Top layers provide greater sensitivity while lower layers register deep pressure. In tests, a three-fingered gripper could detect the inflation pressure of an object, its curvature, and its temperature.

This technology has broad potential applications, from robotic surgery to picking fruit. The researchers hope to apply AI machine learning to train robotic devices to identify and interact reliably with objects of different sizes and characteristics.