SensorNets, a Breakthrough in Stretchable Electronic Skin

As science progresses in the development of wearable technologies, it is becoming obvious that technology should be one that interacts almost seemingly with our bodies. Wearables! In an attempt to create such technology, many companies have developed flexible and stretchable electronics that are meant to move with the skin and somewhat blend with the human somatosensory system. However, no matter the approach, the creation of an intuitive skin-like wearable still relies heavily on the use of complex machinery such as 3D printing, and the final result is still too complex to allow adaptability in the applications.

A team of MIT Media Lab researchers came up with an electronic skin, SensorNets, which promises to remedy those concerns. Inspired by the mechanisms of the human skin and the somatosensory system, SensorNets is a stretchable network of multimodal sensors embedded between layers of deformable fabric or rubbers. The network is like a map of printed circuit boards (PCB) islands of sensor nodes, each composed of a two-layer flexible polyimide PCB with copper traces reinforced with a polyimide stiffener, and a microcontrroller which communicates with multiple sensors and an LED. The system can respond favorably to programming thanks to the “flexible flat cable pad with six-pin in-system programming signals."

For I2C communication between the nodes, each of them is equipped with four pads for four different directions. The network of sensors is made of one master sensor, and the remaining sensors are its “slaves.” The stretchable connection between nodes facilitates communication from one node to another thanks to four serpentine stranded copper wires woven in an elastic ribbon textile.

To test the SensorNets, the researchers organized a series of events which human skin usually experiences such as touching, stretching, folding, heating and exposure to an electromagnetic field. The applications were made using a set of four nodes, and with each experiment, the system accurately revealed which one of the nodes was stimulated. The information communicated by the e-skin during the experiments were, among many, a variation in pressure (Hg), a change in humidity level (%), a fluctuation on the magnetometer, movement of the gyroscope, etc. The team responsible for the e-skin believes that they can improve the stretch and sensitivity of the skin. As they continue working on new materials, they envision that future SensorNets can be used for augmented reality purposes, self-aware objects, and intelligent environments.