Disposable Filter Paper Sensor for Impedimetric Detection of Ascorbic Acid

A filter paper-based disposable, label-free and low-cost sensor for detection of ascorbic acid in aqueous solution is presented in this work. The fabricated sensor consists of a polyaniline coated Whatman filter paper with parallel silver electrodes for impedance measurement. Use of filter paper substrate reduces the cost of the fabrication and facilitates the development of an environment-friendly sensor. Polyaniline having high redox reaction with ascorbic acid facilitates the oxidation of ascorbic acid at low potentials resulting in generation of H
⁺
ions. The presence of H
⁺
ions result in protonation of polyaniline and a subsequent increase in its conductivity. Consequently, the overall impedance between the two electrodes decreases. The sensor can detect aqueous solutions of ascorbic acid in the concentration range of 10 μM-1mM over the frequencies 20 Hz - 2 kHz. Interfering agents i.e., L-arginine and L-aspartic acid, when added to ascorbic acid solution, show negligible impedance changes, thus validating the selectivity of the sensor in detecting ascorbic acid.