Laser-induced graphitized electrodes enabled by a 3D printer/diode laser setup for voltammetric detection of hormones

Contraceptive pills have helped to shape modern society and their use has become more popular over the years. β-estradiol, one of the molecules present in this type of medication, is considered an endocrine disrupting compound (EDC), being nowadays commonly found in water resources. Due to their adverse effects on human health and the environment, even at trace levels, low-cost and rapid-detection approaches capable of reliably detecting EDCs such as β-estradiol are highly keen. As an alternative to the classic and well-established analytical methods for hormone detection, here we propose a simple and low-cost strategy that relies on the use of laser-induced graphitization (LIG) to manufacture electrodes for voltammetric detection of hormone in river and tap water. The LIG electrodes were produced by attaching a diode laser to a commercially available Fused Deposition Modelling (FDM) 3D printer, in which the laser promoted the controlled ablation of the polyimide film adhered to the PLA substrates. Specifically, the manufacturing steps included the 3D printing of the substrate followed by laser scribing a double-sided tape made of polyimide glued onto the surface of the substrate. The 3D printer was able to control the laser movement at specifics positions to manufacture the carbon-based three-electrode system (TES) layout. The usability of the electrochemical sensor was evaluated towards β-estradiol detection, which presented a linear response from 0.25 to 10 µmol L−1 and a limit of detection (LOD) = 80 nM. Spiked samples using tap water and river water reached 91 and 110% of recovery respectively. Our results suggest the proposed approach as an innovative and versatile way to produce low-cost, easily customizable, and reliable electrochemical sensors based on laser ablation on polyimide films.