Table 1:
Commonly Used Polymers in Hydrogel-based Photonics
| Material | Source | Type of Structure | Exploited Property | Application | Refs. |
|---|---|---|---|---|---|
| Alginate | Natural (Seaweed) | Optical Fiber Shell (Cladding) | Low Refractive Index | Optical Fiber Sensing (Metals, Strain, Glucose) | [59,64–66] |
| Alginate | Natural (Seaweed) | Optical Bioinks | Adequate Printing Rheology, Particle Encapsulation | O2 Imaging | [80] |
| Agarose | Natural (Algae) | Thin Films | Electrostatic Interaction with Carbon dots | Heavy-Metal Sensing | [81] |
| Agarose | Natural (Algae) | Linear Fibers, Cladding layers | Cytocompatibility | Waveguide | [70,74] |
| Acrylamide | Synthetic | No-Core Fiber | Analyte-induced Refractive index changes | Ph Sensing, Glucose sensing | [61,62] |
| Acrylamide | Synthetic | Optical Fiber Core | Mechanical Stretchability | Strain Sensing | [59] |
| Poly-Acrylamide | Synthetic | Thin Films | Easy Functionalization | Glucose Sensing | [60] |
| Acrylamide/Methacrylamide | Synthetic | Classic Hydrogel | High Refractive index, high water content | Ophthalmological | [63] |
| Polymethacrylic Acid (PMAA) | Synthetic | Thin Films | Ph Sensitivity | Ph Sensing | [82] |
| Poly(ethylene glycol) Diacrylate (PEGDA) | Synthetic | Optical Fiber Core | High refractive index | Glucose Sensing, Metal Sensing | [62,64–66] |
| Poly(2-vinyl pyridine) P2VP | Synthetic | Thin Films | pH Responsiveness, dynamic swelling | pH Sensing, molecule-induced holographic changes | [83,84] |
| Poly(hydroxy-ethyl methacrylate) (PHEMA) | Synthetic | Thin Films | UV Crosslinking, Ion perfusion | Holographic pH Sensing | [85] |
| Chitosan | Natural (Chitin) | Hydrogel Photonic Crystals | No particular property | pH Sensing | [86] |
| Chitosan | Natural (Chitin) | Lbl films with Dextran | Charge Interactions with Dextran | Glucose Sensing | [77] |
| Gelatin | Natural (Collagen) | Uniform Layer Core | Thermal Crosslinking, Transparency | Waveguide | [70] |
| Gelatin | Natural (Collagen) | Thin Films | Thermal Crosslinking | Holographic Retroreflection | [71] |
| Gelatin/Alginate | Natural | Thin Films | Tunable pH Swelling | pH Sensing | [55] |
| Gelatin Methacryloyl (GelMA) | Natural Modified (Collagen) | Inverse Opal Scaffold | UV crosslinking on templated structures | Structural Colored Hydrogels | [69,87] |
| Cellulose | Natural (Plants) | Multi-core Fibers | Degradability | Waveguide | [75] |
| Silk Fibroin | Natural (Silk) | Core (film) – Clad (hydrogel) structures | Biological Compatibility, Transparency | Waveguide | [76,88] |
Abbreviations: Lbl – Layer-by-layer