Insights into electrochemical behavior in laser-scribed electrochemical paper-based analytical devices

Laser-scribed electrochemical paper-based devices (LS-ePADs) are emerging as a greener alternative to conventional carbon electrochemical sensors since their fabrication does not involve the use of chemicals and the resulting devices show good reproducibility, scalability, and interesting electrochemical properties. This work evaluates the electrochemical properties of LS-ePADs using techniques such as cyclic voltammetry and electrochemical impedance spectroscopy (EIS), together with surface characterization by Raman spectroscopy and scanning electron microscopy. The voltammetric behavior of the porous electrode can be described as diffusional to the top electrode layer. Since the porous structure could affect the mass transport, EIS was used to prove that transport resistance is not limiting the charge transfer process in the electrode response. The graphene-based material that forms the electrode surface, identified by Raman spectroscopy, allows a considerably fast electron transfer between the LS-ePADs and the ferri/ferrocyanide molecules.