Robots can already do a surprising amount. They are also used in areas where people cannot or do not want to go. Now, an artificial skin even enables robots to find chemical substances in their environment. An invaluable advantage in danger zones.
A newly developed artificial skin can detect the explosive TNT, various neurotoxins or pathogenic viruses such as Sars-CoV-2. For this purpose, a number of corresponding electronic sensors are integrated in the skin developed for robots. The technology can be used, for example, in a boat that registers hazardous substances in the water and then automatically steers towards the source, as a research team from the California Institute of Technology in Pasadena (California, USA) led by Wei Gao reports in the journal Science Robotics. It can also be used to control a robotic hand through hand gestures.
So far, sensors in the outer shell of robots have mainly measured physical values such as pressure or temperature. "The integration of chemical sensors for autonomous dry-phase analyte detection on a robotic platform is extremely challenging and significantly underdeveloped," write Gao and colleagues. However, a robotic system that can detect hazardous substances would bring enormous advantages in potential danger zones. Applications are also conceivable in environmental protection and in monitoring public health and safety.
From the outset, the research team attached great importance to the fact that the electronic skin could be produced simply and inexpensively. They developed special inks for all sensors so that the sensor components can be printed on the elastic plastic polydimethylsiloxane (PDMS). The electrical lines, for example silver nanowires, are structured in such a way that they remain electrically conductive even if the artificial skin is stretched.
In order for the chemical sensors to be able to detect dangerous substances such as components of pesticides and neurotoxins or TNT, the hydrogels covering them must contain electrolytes. 'When integrated into a robotic hand, the hydrogel-coated platinum-graphene sensor was able to efficiently sample dry-phase TNT and provide a stable electrical response within three minutes,' write the team of scientists. Other sensors measure virus proteins, temperatures and the pressure exerted by the robot hand on an object.
Gao's group also uses their technology to remotely control a robotic hand. For this purpose, an artificial skin is glued to the forearm of a human being. The sensors measure the electrical impulses that precede every muscle movement. With the help of machine learning algorithms, the signals are assigned to the respective hand movements, such as gripping, releasing, to the left, up.
So the robotic hand grabs an object, as the controlling human shows. With the chemical sensors in the artificial skin of the fingers and the palm of the hand, the robot called "M-Bot" can then analyze substances on the surface of the object.
The researchers demonstrated a possible application for environmental protection with the M-Boat: They equipped a small boat with three sensors (front, left and right). Then they programmed the steering computer so that the boat always moves in the direction in which the highest concentration of a dangerous substance is measured.
In this way, the source of hazardous substances in the water, such as a leak, could be traced. "This technology could significantly improve the cognition capabilities of future intelligent robots and pave the way to many new practical wearable and robotic applications," the study authors write.