Soft Self-Healing Damage Localization Sensor With Reduced Measuring Electrodes

Detection of damage serves as the initial phase for autonomous healing or adaptation to damage in resilient robots. While signaling the occurrence of damage proves beneficial, the more critical requirement lies in localizing the damage to enable targeted actions. This article introduces a soft, self- healing damage localization sensor capable of detecting damage at four distinct locations using only a pair of measuring points (electrodes). The sensor comprises four resistive links, forming a resistive circuit, and operates by measuring the equivalent resistance between two fixed terminals. Damage occurring to each link induces a distinct change in the value of the equivalent resistance. The system is initially characterized at the material level and subsequently at the sensor level through multiple damage trials (the sensor can restore functionality through on-demand healing, achieved by applying a temperature of $90~^{\circ }$ C for 30 min). Finally, the sensor is sandwiched between self-healing layers to form a skin. Out of the 16 damage trials conducted on the sensor, in standalone and embedded configurations, 15 successful localizations were observed. Additionally, reducing the number of electrodes enhances the ease of integration of this technology into various robotic applications, such as the palm of robotic hands.