Strain‐Sensitive Thermochromic Smart Electronic Skin for Joint and Spine Healthcare Applications

Abstract

Electronic skins (E‐skins) that enable interactive and quantitative joint and spine healthcare hold transformative potential for personalized musculoskeletal rehabilitation. However, existing systems face three critical limitations: conventional strain sensors degrade with cyclic large strain due to uncontrolled crack propagation; thermal therapy lacks real‐time adaptive control without feedback; and systems lack user‐interactive monitoring‐therapy integration. Here, iStretch, a mechano‐visual‐thermo adaptive e‐skin is introduced that integrates durable strain sensing, dynamic heat therapy, and intuitive visual feedback via a multiphasic and bilayer architecture. The strain‐sensing bottom layer utilises constrained microcrack propagation in graphene‐liquid metal nanocomposites, achieving high sensitivity (GF = 281), broad sensing range (300%), and exceptional durability (10,000 cycles). Simultaneously, the thermoresponsive top layer provides dynamic visual feedback and heat modulation in response to strain. Its multifunctions are demonstrated for convolutional neural network‐powered omnidirectional motion and gesture recognition, strain magnitude‐adjusted thermotherapy, intuitive thermochromic overheating alerts, and quantitative cervical spine monitoring via wireless sensor arrays.