Interference-Free Tactile Pressure Monitoring on Skin Made Possible with New Stretchable Sensor

The stretchability of pressure sensors has long been a barrier to the creation of robotic hands with truly human-like sensing capabilities and dexterity. Such an advancement could help both inpatient care and in more lifelike prostheses, but the movements required for tasks such as grasping significantly affect performance even of flexible pressure sensors. Researchers at the University of Chicago’s Pritzker School of Molecular Engineering have addressed the issue by designing a new pressure sensor that can be stretched up to 50% while maintaining a consistent sensing performance.

A video released by the team shows the sensor attached to a soft robotic hand, taking the pulse waveforms of a human wrist. The interference-free tactile monitoring is realized through an ionic capacitive sensing mechanism, along with a mechanically hierarchical microstructure. This sensor exhibits 98% strain insensitivity up to 50% strain and a low-pressure detection limit of 0.2 Pa. The sensing mechanism’s pyramid microstructure with a designed stiffness hierarchy allows the interface between the tip of the pyramid and the top electrode — which remains almost unchanged under in-plane stretching — to dominate the system’s overall capacitance.

The full findings were recently published in Science Advances,and the researchers have filed a patent for the technology. Potential applications are many, but the pandemic points to an immediate need for accurate sensors in diagnostic and therapeutic care that can be paired with telemedicine. With this sensor technology, a robot could provide these services in the future. The team is currently working on adding multiple sensors to the hand, replicating multiple fingers and adding sensors that can feel the texture. They are also beginning collaborations to use the system in the creation of electronic skin for prosthetic applications.