This review article gives an overview of the molecular adhesion mechanisms and recent development of mussel inspired functional adhesives.

Conductive hydrogels are widely used in various applications such as artificial skin, flexible and implantable bioelectronics, and tissue engineering. However, it is still a challenge to formulate hydrogels with high electrical conductivity without compromising their physicochemical properties (e.g., toughness, stretchability, and biocompatibility). Additionally, incorporating other functions, such as self-healing, shape memory, and wet adhesion, into conductive hydrogels is critical to many practical applications of hydrogel bioelectronics. In this perspective, we highlight recent progress in the development of functional conductive hydrogels.We then discuss the potential applications and challenges faced by conductive hydrogels in the areas of wearable/implantable electronics and cell/tissue engineering. Conductive hydrogel can serve as an important building block for bioelectronic devices in personalized healthcare and other bioengineering areas.

Wearable epidermal sensors are of great importance to the next generation personalized healthcare. The adhesion between the flexible sensor and skin surface is critical for obtaining accurate, reliable and stable signals. Herein we present a facile approach to fabricate a micro-structured, natural silk fibroin protein based adhesive for achieving highly conformal, comfortable, adjustable, and biocompatible adhesion on the skin surface. The micro-structured fibroin adhesive (MSFA) exhibits reliable and stable bonding force on skin surfaces, even under humid or wet conditions, and can be easily peeled off from the skin without causing significant pain.Such MSFA can greatly improve the sensitivity and reusability of epidermal strain sensors due to its 2 conformal and tunable adhesion on skin surfaces. The MFSA has a great potential to be applied as functional adhesives for various epidermal electronic sensors in the era of personalized healthcare.

Particle size and morphology-dependent gas-detection sensitivity were studied, and the results indicated that the particle stacking mode is a key factor influencing gas sensing performance.