Handing a loved one a rose is a time honored symbol of affection. Its romantic overtones would, of course, be somewhat diminished if the rose were to be crushed during the act. For human hands, such accidents are generally avoidable, but for robots the situation is more challenging.
In order for a robot hand to pick up a rose without deforming it, its skin must be covered in a sensor that is soft, and able to finely detect and report pressure. In this context, graphene oxide (GO) sponges have received a great deal of attention. Pure GO sponges are quite fragile, making them susceptible to damage. Various derivatives have been designed to try to improve the properties of this material, but each of these has had limitations that have prevented their widespread use.
In order to circumvent some of these challenges, a research group from Korea have recently incorporated flower shaped silver nanoparticles into GO sponges. This new material displayed enhanced electrical conductivity, and demonstrated pressure sensitivity two times greater than previous state-of-the-art materials. The electrical conductivity changed predictably as a function of the material strain, and this characteristic enabled fine reporting of the pressure that the skin encountered. This enables a robot to delicately calibrate the pressure applied to a held object.
The GO sponge material was sandwiched between two layers of copper foil and attached to the finger of a robot gripper. When the gripper touched the rose, the slight deformation of the sponge decreased its electrical resistance substantially. The robot gripper was then able to place the rose delicately into a glass vase without damage to the flower. Since the GO sponge stiffness increases substantially with pressure, the robot was then able to successfully transport the vase to another table.
While robot lotharios are perhaps not the intended market for this new material just yet, its unique properties may present new opportunities in various fields.