Sustainable silver nanoparticle-enhanced additive manufactured sensor for cadmium (II) sensing in environmental waters

The development of bespoke, high-performance conductive filament is critical to address limitations of current additively manufactured sensors. In particular, enhancing the sensitivity and reliability of this technology is vital toward their in-the-field applications such as water pollution monitoring. As such, we present the production of filament containing a mix of carbon black (CB) and graphite (G) functionalised with silver nanoparticles (AgNPs) that does not require special printing conditions, special instrumentation, or any post-print modification for the detection of cadmium (II) in environmental waters. The AgNPs are synthesised on graphite flakes using an eco-friendly, aqueous synthesis, without additional reducing agents and their presence is confirmed through SEM, EDX and XPS analysis. The AgNP loaded graphite is incorporated into a filament using recycled PLA and the bio-based plasticiser castor oil, ensuring sustainability is at the heart of the work. The electrodes produced a heterogeneous rate constant, k 0 , of (1.9 ± 0.2) × 10 −3 cm s −1 and were applied toward the detection of cadmium (II) within buffer, tap water, and river water samples. Importantly, using electrodes straight from the print bed with no post-print modification, a Limit of Detection of 0.43 μg L −1 and a Limit of Quantification of 1.44 μg L −1 towards the sensing of cadmium (II), significantly below the worldwide targets of 3–5 μg L −1 , was achievedwas achieved. This work shows a simple but effective approach to include metallic nanoparticles within conductive additive manufacturing filament and the capabilities towards monitoring heavy metal contaminants in water systems. • First report of AgNP doped conductive additive manufacturing filament. • Sustainably produced AgNPs through using graphite as a reducing agent. • No post-print electrode modification required. • Detection limit for cadmium (II) of 0.43 μg L −1 . • Excellent recoveries (87–102 %) achieved for cadmium (II) in real water samples.