Smart-Textile-Based Electrochemical Capacitive Ionic Sensors for High-Performance Epidermal Electronics

Recently, biomedical engineering has placed greater importance on wearable and disposable health-care monitoring devices. Various degradable biosensors have been developed to measure human parameters, such as temperature, pH, pressure, strain, and ion concentration, utilizing bodily fluids, such as sweat, for analysis. In this letter, we developed a new textile-based electrochemical capacitive sensor (TECS) employing multiwalled carbon nanotube-coated cellulose cloth. The electrodes for the TECS were fabricated using a drop coating method, and their surface morphology was evaluated by scanning electron microscopic images. Cyclic voltammetry analysis of the TECS revealed that the fabricated sensor exhibited a sensitivity of 0.29 µA/log [Na
⁺
] in the concentration range of 0–16 mM NaCl. The device operates on an electrochemical capacitive mechanism, exhibiting a specific capacitance variation of 6.9 µF⋅cm
⁻²
across the NaCl concentration range of 0–16 mM. The electrochemical impedance spectroscopic analysis in the frequency range of 10 mHz to 1 MHz indicates the impact of ionic concentration variation, particularly in the low-frequency range. The fabricated TECS offers high sensing performance, biodegradability, and disposability, attributed to its development on cellulose cloth. The developed sensor has potential application in epidermal electronics through integration with smart textiles and offers significant opportunities in wearable biomedical devices.