Environment Adaptable Nanocomposite Organohydrogels for Multifunctional Epidermal Sensors

Abstract

The new generations of wearable materials need to concurrently possess satisfactory biocompatibility and conformability with skin. Different from electronic conductors, ionic conductors report signals using ions like human skin. [3] Ionic conductors can perform many functions that are difficult for electronic conductors. Remarkably, high elastic deformation, high stretchability, and biocompatibility are important parameters for the new-generation ionic conductor applications. [2,4] A flexible device that uses ions as a carrier can be called ionic skin (i-skin). [5] Typical i-skin adopted hydrogel as elastic matrix and deliquescent salts to provide ions such as NaCl, [6] KCl, [7] FeCl 3 , [8] etc. Nonetheless, the water-based materials are particularly sensitive to humidity and temperature, which inevitably leads to dehydration or deliquescent, or even freezing and thus limits the long-term stability of ionic hydrogel conductors. Although the introduction of salts can improve the freezing tolerance of hydrogels, high concentration of ions tends to destroy the interaction inside the network such as hydrogen bonding and ionic bonding which resulting in the poor mechanical strength. [6,9] Ionogel conductors have emerged as another optional materials due to their nonvolatility, high thermal stability, and low temperature resistance. [10,11] However, the inherent toxicity of ionic liquids is a hidden danger for wearable devices which contact with living organism.Natural skin can maintain its flexibility and functionality in harsh environments like freezing and over-heating. For instance, rainbow smelt (Osmerus mordax) have the ability to adapt to very cold water temperatures. This is because their tissues express anti-freeze proteins and glycerol to prevent freezing at sub-zero temperatures. [12] Especially, glycerol (1,2,3-propanetriol or glycerin) as a transparent, odorless and nontoxic liquid, has been widely used in food, cosmetics and pharmaceuticals. After introducing glycerol into water, the hydrogen bonds between H 2 O molecules was disrupted and strong hydrogen bonds were formed between H 2 O molecules and glycerol molecules in the binary solution. [13] Benefitting from this interaction, the obtained organohydrogels can be stored in dry air or low temperature for a long time without losing their mass and flexibility. [14] For instance, anti-freezing conductive double-network organohydrogels were fabricated by soaking a poly(2-acrylamido-2-methylpropane sulfonic Electronic skins, as a revolution in artificial intelligence, have drawn intensive attention in smart prosthetic devices, wearable health monitors and intelligent robot manufacturing. Conductive hydrogels as building blocks have been highlighted in artificial skin research. Nevertheless, the main challenges of hydrogel-based electronics are poor temperature tolerance, weak mechanical robustness and limited stretchability. Herein, an organohydrogel is fabricated with "soft and hard" synergistic networks by combining "soft" polyacryl amide (PAM) and catec...

Self-Healing Bimodal Sensors Based on Bioderived Polymerizable Deep Eutectic Solvent Ionic Elastomers

“…After being cultured for 1 and 3 days, the cell viability of L929 fibroblast cells is still as high as 93.10% and 87.95 (Figure b). Cell viability above 70% can be considered that the material is not physiologically toxic to cells . These results indicate that the biobased bimodal sensor has excellent biocompatibility, mainly due to the biological origin of materials and PDA.…”

“…Cell viability above 70% can be considered that the material is not physiologically toxic to cells. 66 These results indicate that the biobased bimodal sensor has excellent biocompatibility, mainly due to the biological origin of materials and PDA. The biobased bimodal sensor is expected to be a potential future target for directly skin-contact and implantable electronic devices.…”

Amphiphilic drug slow release microspheres fabricated using polyvinyl alcohol, 10‐Undecen‐1‐ol, and multi‐walled carbon nanotubes

“…Then, in vitro cytocompatibility of C‐PVA‐2UO/CNT was determined utilizing L929 fibroblast cells by the LIVE/DEAD viability/cytotoxicity assay kit. Samples with relative cell viability of less than 70% are considered to be cytotoxic 33 . As shown in Figure.…”

“…Samples with relative cell viability of less than 70% are considered to be cytotoxic. 33 As shown in Figure . 7a, the long-term cytotoxicity assessment of C-PVA-2UO/CNT showed excellent cytocompatibility. The staining images of L929 fibroblast cells after 1, 3, and 5 days of culture in 1.0 mg/ml C-PVA-2UO/CNT extract were shown in Figure 7b, indicating that most of the cells in C-PVA-2UO/CNT and the control group remained alive with green color, and a small number of red dots indicate that the dead cells are normal.…”

A Short Review on Organohydrogels: Constructions and Applications

“…Reproduced with permission. [ 39 ] Copyright 2022, Wiley‐VCH GmbH. c) Schematic diagram of rapid preparation of alkali lignin‐copper@water‐EG‐PAAM organohydrogel at room temperature via a self‐catalytic system.…”