Electrochemical humidity sensor based on NaCl/OH-MWCNTs electrolyte for breathing frequency detection

Combining the structure of the primary cell and the operational principle of the humidity sensor, we propose a aluminium/(NaCl/OH-MWCNTs)/copper self-supplied electrochemical humidity (ECH) sensor in this work. Among them, NaCl is used to improve the ionic conductivity of the humidity sensitive electrolyte, while hydroxylated multiwalled carbon nanotubes (OH-MWCNTs) are used to enhance the hydrophilicity and conductivity of the thin membrane. Copper foil and aluminium foil are employed as electrodes. Experimental data show that the ECH sensor can automatically generate voltage over a relative humidity (RH) ranging from 10.9% to 91.5%. It has an output voltage of 0.62 V at 91.5% RH and the maximum output power is 6.57 μW. Based on great humidity sensitive properties, the ECH sensor is suitable for breathing frequency detection. This paper presents a straightforward approach to constructing a high-performance ECH sensor.