Healable, Degradable, and Conductive MXene Nanocomposite Hydrogel for Multifunctional Epidermal Sensors

Abstract

Conductive hydrogels have emerged as promising material candidates for epidermal sensors due to their similarity to biological tissues, good wearability, and high accuracy of information acquisition. However, it is difficult to simultaneously achieve conductive hydrogel-based epidermal sensors with reliable healability for long-term usage, robust mechanical property, environmental degradability for decreased electronic waste, and sensing capability of the physiological stimuli and the electrophysiological signals. Herein, we propose the synthesis strategy of a multifunctional epidermal sensor based on the highly stretchable, self-healing, degradable, and biocompatible nanocomposite hydrogel, which is fabricated from the conformal coating of a MXene (Ti3C2T x ) network by the hydrogel polymer networks involving poly­(acrylic acid) and amorphous calcium carbonate. The epidermal sensor can be employed to sensitively detect human motions with the fast response time (20 ms) and to serve as electronic skins for wirelessly monitoring the electrophysiological signals (such as the electromyogram and electrocardiogram signals). Meanwhile, the multifunctional epidermal sensor could be degraded in phosphate buffered saline solution, which could not cause any pollution to the environment. This line of research work sheds light on the fabrication of the healable, degradable, and electrophysiological signal-sensitive conductive hydrogel-based epidermal sensors with potential applications in human–machine interactions, healthy diagnosis, and smart robot prosthesis devices.

Scalably Nanomanufactured Atomically Thin Materials‐Based Wearable Health Sensors

“…The TiO 2 /Ti 3 C 2 T x /PAA hydrogel was then used as the electrodes to successfully measure ECG, EOG (eye movements), and EMG (arm movements) signals. Li et al [ 8 ] also developed an electrophysiological sensor consist of Ti 3 C 2 T x . The sensor was prepared by the conformal coating of a Ti 3 C 2 T x network by the hydrogel polymer networks involving PAA and amorphous calcium carbonate (ACC).…”

“…Wearable electronics exhibiting characteristics such as light‐weight, ultrathin form factors, low energy consumption, biocompatibility, and superior mechanical properties could enable non‐invasive, imperceptible sensor systems for physical, chemical, and physiological monitoring over an extended time. [ 5,6 ] Some health‐related sensing modalities that have been demonstrated for wearable devices include but are not limited to sensors that can precisely capture various electrograms such as electromyography (EMG), [ 7,8 ] electrocardiography (ECG), [ 7,9–11 ] electrooculography (EOG), [ 11 ] and electroencephalography (EEG), [ 7 ] mechanical signals (e.g., pulse), and chemical signals [ 12–15 ] (e.g., concentrations of Na + , K + , glucose, dopamine, etc. generated in human sweat and fluid).…”

Self-Healing Mechanism and Conductivity of the Hydrogel Flexible Sensors: A Review

“…To reduce environmental pollution and save resources, it is necessary to study self-healing materials that can prolong life cycles via the autonomous repair of damage [81]. The self-healing ability allows the hydrogel to recover from the damage it has sustained, thus maintaining its main properties and functions, and finally extending the service lifetimes of the materials [82][83][84]. The self-healing properties of polymeric materials can be divided into extrinsic and intrinsic self-healing, depending on whether the self-healing component is inserted into the polymer or the original component in the polymer matrix.…”

Rational engineering and applications of functional bioadhesives in biomedical engineering

“…Recently, Mxene hydrogel nanocomposites have been developed as a bioadhesive for epidermal sensors. [154] Mxene is a conductive two-dimensional nanomaterial with a high surface area, abundant surface functional groups (-O, -F, -OH, etc. ), and high conductivity.…”