Stretchable Wireless Sensor Skin for the Surface Monitoring of Soft Objects

Abstract

Like rigid objects, also soft and elastic manufactured materials for industrial and biomedical applications are subjected to fatigue stress that might speed up the aging process and even cause premature failures. The occurrence of early signs of damaging, like the arising of surface cracks, could avoid more severe critical events, especially when biomedical soft prosthesis are involved (such as artificial breast, stomach, bladder).A thin-film stretchable wireless sensor for surface monitoring is here proposed. The device is based on a densely distributed electrode exploiting, at the macro-scale, a Space-Filling Curve pattern, and a meandered profile in the micro-scale. Interconnection with a wrapped Radiofrequency Identification antenna permits to transmit the status of the electrode to remote, with no battery onboard. The device was manufactured by means of electron beam deposition over a thin elastomer. Surface defects of size larger than 0.9mm to 9mm can be detected with probability of 60% to 90%, respectively. Thanks to its double-scale meanderings, the sensor is highly tolerant to stretch keeping its shape nearly unchanged up to a 35% strain.