**3. Conclusions**

Heavy metal determination by electrochemical methods has evolved over time, following the analytical trends of miniaturization and, more recently, sustainable and eco-friendly processes. Paper-based platforms are the next alternative to low-cost and easy-to-use electrodes. In this chapter, the main designs reported in the literature have been critically analyzed. The modification with nanomaterials or metal films in order to increase their conductivity properties was found successful strategy. This confirms that cellulose-based platforms are the foundations of a new generation of versatile and low-cost electrochemical sensors.
