Dual-Templated Carbon Aerogel Beads: Preparation, Structure and Applications in Physiological Health Monitoring.

Carbon aerogels beads have gained significant interest owing to their reduced processing times compared to monoliths. However, precise control over their architecture and porosity remains a significant challenge. Here, we introduce a novel dual-templating strategy using a bio-based structuring additive and a soft template to regulate shape and microstructure of the resorcinol-formaldehyde (RF) based carbon aerogel beads. The synthesis process is strategized using central composite design (CCD) in response surface methodology (RSM), and the optimized beads are used to fabricate humidity sensor arrays. The individual and interactive effects of the process variables template:RF mass ratio, density, and ID/IG ratio on humidity sensing performance are further analyzed through the regression equation in RSM. Soft templating of the aerogels delivered optimum internal porous network to enable rapid diffusion of water molecules for humidity sensing through bulk electronic conduction at low humidity to water-mediated proton conduction at high humidity. The prepared TCA1 (Templated carbon aerogel) possesses an SBET of 518.2 m2g- 1 and a pore volume of 0.03 cm3g- 1. The sensor demonstrated fast response/recovery times of 22/6 s, a sensitivity of 1.27% RH- 1, and stable operation over repeated cycles, highlighting its potential for continuous humidity monitoring and healthcare applications.