Recent development in polysaccharide-based conductive hydrogels and their potential applications in sensing: An extensive review

Reducing toxic petroleum emissions from fossil fuel burning is a critical worldwide issue, directly linked to safeguarding human health and environmental sustainability. Greenhouse gases emitted from energy production not only harm ecosystems but also provide significant threats to human health. Consequently, there is an immediate need for sophisticated gas sensors that provide elevated sensitivity, quick reaction times, and minimal detection thresholds—particularly those functional at ambient temperature. Conventional sensing materials, including metal and metal oxide adsorbents, have potential but often need high temperatures for optimal performance. To address this constraint, researchers have used conducting polymers—specifically polyaniline and its derivatives—incorporated into hydrogel composites. These materials provide a unique amalgamation of conductivity, flexibility, and performance under ambient conditions, making them ideal candidates for next-generation gas sensors. This study provides a thorough examination of current developments in the synthesis, characterization, and use of conductive hydrogel composites. Particular attention is given to their function in identifying harmful gases, highlighting advancements over the last five years. The paper examines the essential sensing principles, identifies existing obstacles, and delineates future trajectories for this potential category of materials in electrochemical sensing technologies. • The current review provides an overview of conductive hydrogel methods. • Hydrogel composites based on conducting polymers, such as polyaniline and their derivatives, are reviewed. • Recent studies conducted over the last five years that shed light on the underlying principles governing conductive hydrogel composites are reviewed. • The key applications of conductive hydrogel-based devices with flexible structural engineering in a variety of industries are reviewed.