Facile Preparation of a Self-Adhesive Conductive Hydrogel with Long-Term Usability

Abstract

Although conductive hydrogels (CHs) have been investigated as the wearable sensor in recent years, how to prepare the multifunctional CHs with long-term usability is still a big challenge. In this paper, we successfully prepared a kind of conductive and self-adhesive hydrogel with a simple method, and its excellent ductility makes it possible as a flexible strain sensor for intelligent monitoring. The CHs are constructed by poly­(vinyl alcohol) (PVA), polydopamine (PDA), and phytic acid (PA) through the freeze–thaw cycle method. The introduction of PA enhanced the intermolecular force with PVA and provided much H+ for augmented conductivity, while the catechol group on PDA endows the hydrogel with self-adhesion ability. The PVA/PA/PDA hydrogel can directly contact with the skin and adhere to it stably, which makes the hydrogel potentially a wearable strain sensor. The PVA/PA/PDA hydrogel can monitor human motion signals (including fingers, elbows, knees, etc.) in real-time and can accurately monitor tiny electrical signals for smile and handwriting recognition. Notably, the composite CHs can be used in a normal environment even after 4 months. Because of its excellent ductility, self-adhesiveness, and conductivity, the PVA/PA/PDA hydrogel provides a new idea for wearable bioelectronic sensors.

Highly Adhesive, Ultrafast Self-Healing, and Conductive Dopamine-Based Polymer Hydrogels for Sensitive Human Motion Sensing

“…Table S5 lists the comparison of the hydrogels studied in this work with the studies reported in the last 3 years in terms of tensile properties, adhesion, self-healing properties, sensitivity, etc. Compared with the properties of the other materials listed, the hydrogels studied in this work showed good comprehensive properties. − ,− …”

“…This property makes it well suited for creating adhesive hydrogels that mimic mussel adhesion capabilities on nearly any surface. For instance, Bai et al developed a conductive self-adhesive hydrogel using poly­(vinyl alcohol) (PVA), polydopamine (PDA), and phytic acid (PA) via freeze–thaw cycling, with a tensile strain below 450% and a tensile stress under 225 kPa. The adhesive strengths for wood, pig skin, metal, and PP surfaces were 14.9, 13.4, 7.2, and 4.2 kPa, respectively.…”

Conductive nanocomposite hydrogels for flexible wearable sensors

“…10b). 128 Subsequently, liquid conductive phytate was introduced to prepare conductive, water-retaining, and self-adhesive nanocomposite hydrogels by cyclic freeze–thawing, exhibiting enhanced ductility, biocompatibility, and homogeneity. The introduction of phytic acid enhanced the intermolecular forces with the polymer substrate, and the combination of the catechol group on PDA and hydrogen bonding in the system endowed the hydrogel with good adhesion properties, which could be directly and stably adhered to the skin surface.…”

Recent Advances in Machine Learning Assisted Hydrogel Flexible Sensing

“…The excellent performance of the hydrogel can detect the movement of the knuckles, wrists, elbows and ankles, as well as the heartbeat, pulse and other small deformation detection. [135][136][137][138][139] To further enhance capabilities in the field of action recognition, ML algorithms can be introduced. For example, Li et al designed a dual-network polyacrylamide/sodium carboxymethyl cellulose/ tannic acid (PAM/CMC/TA) hydrogel with excellent transparency, adhesion, and remodeling properties.…”