Super-Stretchable Resistive Strain Sensor Based on Ecoflex-Gold Nanocomposites

Superstretchable resistive strain sensors can reversibly undergo severe deformations in response to different mechanical stimuli, leading to a variation in their ohmic resistance. They are finding an increasing number of applications in wearable electronics, biomedical devices, and soft robotics. The development of fabrication process of reliable, highly sensitive, and biocompatible superstretchable strain sensors remains a challenge, especially in view of their integration with medical devices. Here, we demonstrate the fabrication of a high-strain resistive sensor based on Ecoflex elastomeric films and conductive Au clusters, obtained by supersonic cluster beam deposition. An extensive characterization of the electromechanical behavior of the sensor shows stable operation up to 4500 working cycles, with a maximum strain of 500% and a gauge factor of 124. Different mechanical stimuli, such as elongation and indentation, can be detected, and the easy coupling of the sensor with an inflatable balloon-type urinary catheter is demonstrated. Aiming at shedding light on the observed electromechanical mechanisms, the nanostructured morphology of the metal-polymer hybrid layer was investigated by low-vacuum scanning electron microscopy.