Electronic Skin Developed with Multi-Directional Touch Sensing

A research team from the Chemnitz University of Technology and Leibniz IFW Dresden have developed a new approach for the miniaturization of sensors in electronic skin systems — flexible electronic systems that try to mimic the sensitivity of natural human skin. Tiny hairs on the skin's surface can both perceive and anticipate the lightest tactile sensation. They can even recognize the direction of touch, a capability that most modern skin systems have lacked. The approach developed by Chemnitz and Dresden marks a major step forward in e-skin technologies, using a new method for the miniaturization and integration of soft, ultra-compact sensor units with directional tactile sensitivity.

Led by Dr. Oliver G. Schmidt, the researchers explored new avenues to develop extremely sensitive and direction-dependent 3D magnetic field sensors that can be integrated into e-skin systems. The magnetic sensing modality is a recent introduction to such systems, but in previous attempts, the integration density of the magnetic sensors has been limited, as have the vector properties, which are hampered by the sensor's ability to only perceive field components in one or two directions.

Described in a paper published in Nature Communication,the new 3D magnetic sensor is composed of an array of self-assembled micro-origami cubic architecture with biased anisotropic magnetoresistance (AMR) sensors, manufactured via a wafer-scale process. Integrating these sensors into an e-skin with embedded magnetic hairs allows for the real-time multidirectional sensing that has been missing from electronic skin systems.

The core of the system, the AMR sensor, can be used to precisely determine changes in magnetic fields. In fact, they are currently used in applications like speed sensors in cars or to determine the position and angle of moving components within a range of machines. The sensors are folded into 3D architectures that can resolve the magnetic vector field in three dimensions; these micro-origami arrangements also enable a large number of elements in a small space, arranged in geometries not available via conventional microfabrication processes.

Once integrated into an elastomeric e-skin — similar to biological skin interlaced with nerves — the 3D sensors detect when a magnetic hair on the surface is touched and bends. This allows the sensor matrix to register not only slight movements of the hairs but to determine the exact direction of that movement. This capability is important in applications where humans and robots work closely together, detect nuance in intended contact and prevent unintended collisions, and open new possibilities in the development of artificial skin.