Agarose-based hydrogels have many advantages for in vitro research. However, their poor ionic and electrical conductivities make it challenging to track the molecular diffusion of target analytes, such as cationic dyes like Methylene Blue (MB), in situ. Rigid implantable electrodes provide a solution for sensing the dynamic transport of these analytes within soft materials. Nevertheless, integrating ionic and electrically conductive soft materials into soft hydrogels presents an even better solution. In this research, we will demonstrate a simple method for synthesizing ionogels from phosphonium-based ionic liquids. We will describe the interfacial and electrical properties of the synthesized ionogel, highlighting its utility as a soft ionic conductor. Furthermore, we will showcase how these soft ionic conductors can be implanted to track the molecular diffusion dynamics of MB in agarose-based hydrogels in situ. This research will also address the stability and feasibility of the ionogel for prolonged use, focusing on its self-healing characteristics, swelling behavior, and wetting properties. Using straightforward capacitance measurements, we will demonstrate how these materials can be utilized for in situ sensing, which will soon find applications in environmental engineering and biomedical research.
