Printable Polar Silicone Elastomers for Healable Supercapacitive Strain Sensors

Abstract

Soft strain sensors with high sensitivity and the ability to recover from damages are required in the emerging field of self‐healing soft robotics. Herein, printable supercapacitive strain sensors that can heal upon moderate heating (75 °C for 10 min) and exhibit a 30 times higher sensitivity than PDMS‐based sensors are developed. For the sensor's core layer and electrode, a nitrile‐functional polysiloxane that contains an active ionic initiator and can heal by siloxane equilibration at elevated temperatures is used. Supercapacitive strain sensors prepared from the elastomer are highly sensitive at low strains of 0–30%, enabled by the electric double‐layer formation of the ionic initiator. After healing, the sensors exhibit nearly unaltered performance in tensile testing. Due to the thermoreversible nature of the elastomer network, patterned core layers with different microstructures can be printed by direct ink writing. The capacitive sensors based on these microstructured films reach a higher sensitivity and linearity than those based on unstructured films. Finally, the sensor is integrated into a soft robotic finger and the sensor's ability to determine the bending angle is validated by motion capture. This technology can provide new opportunities to equip soft robotic devices with custom‐printed, healable strain sensors.

Unravelling the Influence of Binder Typology during the Additive Manufacturing of Hybrid Multi-Channel Cylinders for Catalytic Purposes

“…Unlike subtractive manufacturing, where an item is realized via computer numerical control (CNC) machining with the removal of materials from a bulk structure, additive manufacturing is a novel 3D technique that can realize complex geometries from the base upwards, by adding successive layers to create the final product [12]. Among the various types of strategies behind additive manufacturing, direct ink writing (DIW) uses a material at controlled rheological properties as an ink to be squeezed out through a syringe nozzle at a regulated flow rate [13], resulting in a flexible and powerful approach for the prototyping of advanced functional materials, composites and structures with unique shapes and applications in the field of polymers or resins [14][15][16][17], electrodes [18], ceramics [19], sensors [20] and reactive inks [21], usable in all technological fields of science, included biomedical applications [22,23]. In the field of catalysis, the extrusionbased method is widely utilized for obtaining a catalyst with tailored structures, with a specified shape and a suitable size for minimizing pressure drops, preserving uniform flow distribution and improving mass and heat transfer phenomena [24][25][26].…”