Development of conductive inks for electrochemical sensors and biosensors

The monitoring of species of medical, environmental, and industrial interests has been urgently demanded. Several times, the necessity of point of care and/or point of use is important to obtain precise and rapid quantification, in which wearable and flexible disposable electrochemical sensors and biosensors have been great alternatives. In this context, a short review describing the main advances in the fabrication and development of conductive inks for the construction of miniaturized and disposable electrochemical devices is presented. Electrochemical devices developed from conductive inks have been an innovative system that promotes flexibility for the design of the electrodes. The growing increase in the number of researches regarding the development of inks is driven by the search for simplicity, low-cost, less waste generation, mass production, and environmentally friendly manufacturing methods. The present review focuses on alternative conductive inks and their compounds, binders, and conductive materials for electrochemistry. The binder such as varnishes, natural resins, and natural polymeric compounds will be presented, once they promote the dispersion of conductive material, as well as the adhesion on the substrate. Special attention is given to conductive materials. We highlight some nanostructured materials such as platinum, silver, and gold nanoparticles, due to their great conductivity and extensive use to develop electrochemical sensors. Inks and electrodes from carbon-based materials are also discussed, such as graphite, carbon nanotubes, carbon black, and graphene. The biocompatibility of these materials, especially important for wearable sensors, will also be approached. Finally, we present new perspectives on the development of sensors and biosensors using conductive inks.