Lignin-based hydrogels in pressure sensor applications.
| Hydrogel composition | Lignin type | Synthesis | Properties | Applications | References |
|---|---|---|---|---|---|
| Polyvinyl alcohol, lignin-silver hybrid nanoparticles (Lig-Ag NPs) | Alkaline lignin | Alkaline lignin and AgNO3 combine to form Lig-Ag NPs, which are then implanted in a PVA matrix to create a porous hydrogel by dynamic hydrogen bonding and ammonia release | Porous structure (from NH3 release), exceptional compressibility, high pressure sensitivity, steady and fast signal response | Piezoresistive pressure sensors | [82] |
| Poly (acrylic acid), lignosulfonate sodium (LS), ferric ions (Fe3+) for asymmetric adhesion | Lignosulfonate sodium (LS) | LS was incorporated into PAA to form a hydrogel, followed by Fe3+ ion soaking on the upper surface to induce asymmetric adhesion | Conductivity: ~0.45 S/m, stretchability: ~2,250%, compressive modulus: ~20 kPa (very soft), wearable comfort, anti-interference in sensors | Wearable pressure sensors, skin-adherent but anti-adhesive tissue dressings | [84] |
| Poly (acrylic acid) (PAA), 3-allyloxy-2-hydroxypropyl lignin (AHP-lignin) | AHP-lignin | Free-radical polymerization was used to create multifunctional hydrogels by combining AHP-lignin with PAA | Self-adhesion, conductivity, UV shielding capacity, pressure sensitivity to small forces, biocompatibility | Wearable pressure sensors, body motion monitoring | [85] |
| Sodium lignosulfonate–silver, SBMA ([2-(methacryloyloxy) ethyl] dimethyl-(3-sulfopropyl) ammonium hydroxide) | Sodium lignosulfonate | Using sodium lignosulfonate–silver nanoparticles and SBMA as functional monomers, hydrogel was created at room temperature through redox-triggered polymerization | Excellent mechanical strength and flexibility, antimicrobial activity (from silver), antioxidant activity (from lignosulfonate), electrical conductivity (suitable for sensors), anti-freezing ability (due to SBMA), rapid gelation at room temperature | Pressure/strain sensors, wound dressings | [86] |
HK: Conceptualization, Visualization, Data curation, Writing—review & editing, Writing—original draft. Disha: Data curation, Writing—review & editing. KS: Data curation, Writing—review & editing. OS: Project administration, Supervision, Writing—review & editing. BS: Conceptualization, Investigation, Project administration, Supervision, Writing—review & editing. All authors read and approved the submitted version.
The authors declare that they have no conflicts of interest.
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The authors would like to thank the Department of Pharmaceutical Sciences and Drug Research, Punjabi University, Patiala and Bioinformatics center (BIC) sponsored by Department of Biotechnology for providing a computational facility under the BIC (Bt/PR39876/Btis/137/7/2021), New Delhi, India. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
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