delamination of electronic conductors and substrates pose significant challenges in strain sensor applications such as detection of biological signals of human motion. [7] Furthermore, these traditional sensors are mounted on the skin by additional adhesives, mechanical clamps, or straps to achieve long-term practical application. [8] Currently, researchers have focused on identifying new promising candidate materials to overcome these defects.Hydrogels are three-dimensional (3D) polymeric networks with good stretchability, viscoelasticity, and swelling properties. [9] Due to their outstanding performance, many stretchable hydrogels have been increasingly applied to the field of wearable strain sensors. [10][11][12][13][14] For instance, Li et al. [15] developed a dual physically crosslinked polymer hydrogel with hydrogen bonding and ionic coordination. As a strain sensor, it has high sensitivity to pressure and deformation and can detect the human body movement. However, this hydrogel requires additional double-sided tape to be attached to the skin due to the lack of self-adhesion, which limits its application in wearable devices. Thus, an extended function (e.g., self-adhesive performance) is promising for motion detection and allows easy skin adhesion. Currently, the development of a hydrogel-based composite strain sensor with excellent stretchability and selfadhesive properties remains a considerable challenge. Recently, mussel-inspired adhesive hydrogels have demonstrated excellent performance and served as an inspiration for the design and fabrication of other types of self-adhesive hydrogels. Mussels can firmly adhere to all surfaces by noncovalent and covalent chemical interactions regardless of surface roughness. [16] Dopamine (DA), which has a protein-catechol group that is similar to that used in mussel adhesion, has been widely used to fabricate selfadhesive and conductive hydrogels. [17] More importantly, DA provides a new perspective for the development of wearable strain sensors with excellent self-adhesive properties. For instance, Liu et al. [18] reported a hydrogel-based self-adhesive and self-healing epidermal strain sensor by adding Polydopamine (PDA) to PVA; the developed sensor can detect minute epidermal deformations (0.1% strain) and large body movements (10-75% strain) such as throat vibration and finger bending. In addition, it can be used in the field of low-intensity strain sensing. Furthermore, Zhang et al. [19] prepared a conductive, healable, and self-adhesive hydrogel-based sensor by dynamic supramolecular cross-linkingThe latest generation of wearable devices features materials that are flexible, conductive, and stretchable, thus meeting the requirements of stability and reliability. However, the metal conductors that are currently used in various equipments cannot achieve these high performance expectations. Hence, a mussel-inspired conductive hydrogel (HAC-B-PAM) is prepared with a facile approach by employing polyacrylamide (PAM), dopamine-functionalized hyaluronic acid (HAC), ...
