Digital fabrication of 3D printed bismuth sparked sensors for electrochemical sensing

Abstract

The fast and in-house fabrication of high-performance metal-based sensors is highly desirable in modern electrochemistry. Compared with plain carbon electrodes, metal-modified sensors offer wider applicability and higher sensitivity to electroanalytical methods. Herein, we introduce the entirely digital fabrication of biodegradable 3D printed thermoplastic sensors, in-situ modified with "green" spark discharge generated bismuth particles (BiPs). The hybrid fabrication process of these metal/plastic sensors employs two different printing methodologies, including fused deposition modeling for the 3D printing of the plastic electrode and printing via sparking for the deposition of BiPs on the electrode surface. More specifically, the sensors are 3D printed from a carbon black/polylactic acid filament by a 3D printer and then are modified with BiPs through repetitive sparking spots, applying an electrical discharge at 1.2 kV between a Bi-tip and the 3D printed electrode. The sparking process is performed using a desktop device equipped with a Bi-sparking head and a high voltage power supply. Full control of the sparking head movements by custom g-code software allows for the toposelective application of a predetermined number of sparking spots over the electrode surface. These ready-to-use 3D printed metal/plastic sensors are tested for the anodic voltammetric determination of lead and cadmium and the cathodic voltammetric determination of riboflavin in real samples, offering low limits of detection. These features highlight the potential of the 3D printed sparked sensor as a new generation candidate for the development of printed-at-point and sensitive metal-based sensors.