Highly Stretchable, Adhesive, and Mechanical Zwitterionic Nanocomposite Hydrogel Biomimetic Skin

Abstract

The artificial skin-like stretchable ionic sensor device usually requires a synergistic effect of reliable adhesion between human machine interface, reasonable mechanical strength, and visually displayable transparency. A plant-inspired zwitterionic hydrogel was prepared through rapid UV initiation in the existence of cellulose nanocrystals as physically crosslinker and reinforcing agent. The resulting transparent zwitterionic nanocomposite hydrogel successfully brings the synergistic advantages of robust adhesive strength between diversified substrates such as skins, plastics, glass, and steels with remarkable mechanical properties of a superior stretchability over 1000% strain, a mechanical tensile strength up to 0.61 MPa, and compressive strength up to 7.5 MPa, manifesting in superior ionic transport performance, simultaneously. Furthermore, the zwitterionic nanocomposite hydrogel was fabricated as a wearable compliant stretchable pressure–strain sensor in the modality of the skin-adhesive patch to be sensitive to human motion such as finger touch and speech recognition for personal healthcare of patient sensory rebuilding and physiological data acquisition. It maintains compressive cycling sensibility at diverse pressure during 0.5, 1.0, and 1.5 Hz, respectively. The multifunctional zwitterionic nanocomposite hydrogel could also be assembled into flexible electrical devices such as luminescent display and information transfer between human and robot communication for mechanosensory electronics and artificial intelligence.

Progress in wearable electronics/photonics—Moving toward the era of artificial intelligence and internet of things

“…Flexibility, stretchability and light‐weight of wearable electronics, as the key factors determining the comfort level of users and the portability of devices, have drawn tremendous attention across the world for developing finger/glove sensors with such characteristics 122‐125 . The common flexible strain sensors are normally based on resistive sensing 123,126‐137 or capacitive sensing, 138,139 whose output signals can dynamically respond to the variation of applied force or strain under continuous motions. A finger‐bending strain sensor is presented using stretchable gallium‐based conductors, as indicated in Figure 3C 140 .…”

pH-dependent nanodiamonds enhance the mechanical properties of 3D-printed hyaluronic acid nanocomposite hydrogels

“…The functionality of a thermoplastic biodegradable polymer or natural biopolymer with versatile chemical modification has been extensively studied for theranostics and drug delivery. There have been several recent studies exploring the microscopic mechanical properties of these polymers, as well as their cellular functionality and drug delivery [8][9][10][11][12][13]. In particular, modified nanocomposite hydrogels with enhanced mechanical and functional properties have been beneficial in the fields of tissue engineering, medical devices, and depot formulation.…”

Highly Strong and Transparent Ionic Conductive Hydrogel as Multifunctional Sensors

“…[ 18–20 ] To address this problem, the ionic conductive hydrogels were developed and investigated recently. [ 21–25,35 ] Yang and Yuan designed a transparent ionic conductive hydrogel, which can be used as wearable skin‐like strain sensors, while it exhibited relatively low tensile stress (0.22 MPa) and compressed stress (<2.0 MPa). [ 25 ] High mechanical performance is highly essential to support tremendous mechanical loads and avoid undesired rupture when the ionic conductive hydrogel is applied in the areas of stretchable sensors and imitated soft tissue.…”

“…[ 21–25,35 ] Yang and Yuan designed a transparent ionic conductive hydrogel, which can be used as wearable skin‐like strain sensors, while it exhibited relatively low tensile stress (0.22 MPa) and compressed stress (<2.0 MPa). [ 25 ] High mechanical performance is highly essential to support tremendous mechanical loads and avoid undesired rupture when the ionic conductive hydrogel is applied in the areas of stretchable sensors and imitated soft tissue. [ 26 ] To enhance the mechanical performance, numerous double‐network hydrogels with high strength were fabricated by introducing PVA matrix.…”