Bio-Inspired Electronic Skin Sensors for Precise Motion Tracking

Researchers have developed “electronic skin” sensors capable of mimicking the dynamic process of human motion. They attempted to imitate the biological and dynamic process of the skin of the human hand to enable objects to behave similarly.

The dual-mode sensor measures both the magnitude and load of movement — such as the effort of swinging a tennis racquet — as well as rate, duration, and direction. The trick was to decouple this measurement and understand how the separate parameters influence each other; for example, bouncing a tennis ball gently on a racquet requires different input than serving a ball to an opponent. Those same variables come into play when a person with a prosthetic arm needs to differentiate between handling an egg or carrying a watermelon.

The sensors can be applied to help people capture the magnitude for pressing, bending, and other motions. They also can be used on soft robotics to manipulate delicate objects, like catching a fish, or even in a disaster when they may need to crawl into irregular spaces and move debris.

The data is informed by synergy created between the piezoelectric and piezoresistive signals. Piezoelectric signals measure outside force, such as pressure, to create electrical charge while piezoresistive signals mitigate the current. The dual-mode sensors are sandwiched together, with two internal layers of pyramid-shaped microstructures facing one another. The microstructures measure magnitude and duration measurements from the piezoresistive layer and the dynamic loading rate and direction from the piezoelectric layer. This synergistic effect allows for a high sensitivity over a broad pressure and frequency range, meaning that researchers can precisely measure the force and flexibility needed to imitate specific movements.