Additive manufacturing electrochemistry: An overview of producing bespoke conductive additive manufacturing filaments

Additive manufacturing represents a state-of-the-art technology that has been extensively disseminated in both the academic and industrial sectors. This technology enables the cost-effective, simple, and automated production of objects with diverse designs. Moreover, within the academic community, additive manufacturing has provided genuine scientific revolutions, particularly in the field of electrochemistry, due to the accessibility of the Fused Filament Fabrication printing methodology, which utilizes thermoplastic filaments for electrochemical platforms. Additive manufacturing has facilitated the production of conductive components for various applications, including electrochemical sensors, batteries, supercapacitors, and electrical circuits. Within recent years, the scientific community has taken an interest in bespoke filaments that are doped with highly conductive particles, which can be optimized and tailored enabling groups to produce a wide range of filaments with uncountable applications. Thus, the present review article explores the distinct methods of bespoke filament manufacturing, emphasizing its significance in the scientific landscape, and investigating the principal materials utilised in its production, such as thermoplastics, plasticizers, and conductive substances, focusing on electrochemistry applications. Furthermore, all reported additive manufacturing methods will be thoroughly discussed, along with their main advantages and disadvantages. Last, future perspectives will be addressed to guide novel advancements and applications of bespoke filaments for use within electrochemistry

Utilising bio-based plasticiser castor oil and recycled PLA for the production of conductive additive manufacturing feedstock and detection of bisphenol A

The production of electrically conductive additive manufacturing feedstocks from recycled poly(lactic acid) (rPLA), carbon black (CB), and bio-based plasticiser castor oil is reported herein. The filament was used to print additively manufactured electrodes (AMEs), which were electrochemically benchmarked against geometrically identical AMEs printed from a commercially available conductive filament. The castor oil/rPLA AMEs produced an enhanced heterogeneous electrochemical rate constant of (1.71 ± 0.22) × 10−3 cm s−1 compared to (0.30 ± 0.03) × 10−3 cm s−1 for the commercial AME, highlighting the improved performance of this filament for the production of working electrodes. A bespoke electroanalytical cell was designed and utilised to detect bisphenol A (BPA). The AMEs made from the castor oil/rPLA gave an enhanced electroanalytical performance compared to the commercial filament, producing a sensitivity of 0.59 μA μM−1, a LOD of 0.10 μM and LOQ of 0.34 μM. This system was then successfully applied to detect BPA in spiked bottled and tap water samples, producing recoveries between 89-104%. This work shows how the production of conductive filaments may be done more sustainably while improving performance

Low-cost, facile droplet modification of screen-printed arrays for internally validated electrochemical detection of serum procalcitonin

This manuscript presents the design and facile production of screen-printed arrays (SPAs) for the internally validated determination of raised levels of serum procalcitonin (PCT). The screen-printing methodology produced SPAs with six individual working electrodes that exhibit an inter-array reproducibility of 3.64% and 5.51% for the electrochemically active surface area and heterogenous electrochemical rate constant respectively. The SPAs were modified with antibodies specific for the detection of PCT through a facile methodology, where each stage simply uses droplets incubated on the surface, allowing for their mass-production. This platform was used for the detection of PCT, achieving a linear dynamic range between 1 and 10 ng mL−1 with a sensor sensitivity of 1.35 × 10−10 NIC%/ng mL−1. The SPA produced an intra- and inter-day %RSD of 4.00 and 5.05%, with a material cost of £1.14. Internally validated human serum results (3 sample measurements, 3 control) for raised levels of PCT (>2 ng mL−1) were obtained, with no interference effects seen from CRP and IL-6. This SPA platform has the potential to offer clinicians vital information to rapidly begin treatment for “query sepsis” patients while awaiting results from more lengthy remote laboratory testing methods. Analytical ranges tested make this an ideal approach for rapid testing in specific patient populations (such as neonates or critically ill patients) in which PCT ranges are inherently wider. Due to the facile modification methods, we predict this could be used for various analytes on a single array, or the array increased further to maintain the internal validation of the system

3D-printed immunosensor for the diagnosis of Parkinson's disease

3D printing technology is a strategic tool for the development of electrochemical sensors and biosensors since it is possible to obtain versatile devices quickly and at a low cost. In this work, an arrangement of 3D-printed electrodes (working, pseudo-reference, and auxiliary) was applied for the detection of PARK7/DJ-1 protein in blood serum and cerebrospinal fluid samples. The immunosensor surface was previously chemically and electrochemically activated to promote the increase of the active sites and the conductivity, allowing the covalent immobilization of the biological species (antibodies) and improving its electrochemical performance. The detection was carried out by impedimetric (5.0 −200 µg L−1), and voltammetric measurements (5.0 −500 µg L−1), showing limits of detection of 1.01 and 3.46 µg L−1. The 3D-printed immunosensor also achieved good repeatability and reproducibility from normal to abnormal levels of PARK7/DJ-1 protein, aiming for the diagnosis of Parkinson's disease in different stages of the disease

Conductive recycled PETg additive manufacturing filament for sterilisable electroanalytical healthcare sensors

Current reports of healthcare sensors within literature that use additive manufacturing electrochemistry all utilise conductive PLA, which is unsuitable for widespread use within the industry. Poly(ethylene terephthalate glycol (PETg) is a polymeric material with proven attributes for additive manufacturing due to its thermal and mechanical properties. Likewise, its excellent chemical stability transforms PETg into a desirable alternative for developing healthcare sensing devices. In this work, we report the production, physicochemical and electrochemical characterisations, as well as the electroanalytical performance of an enhanced electrically conductive additive manufacturing filament made with recycled poly(ethylene terephthalate glycol (rPETg) and a combination of carbon black, multi-walled carbon nanotubes and graphene nanoplatelets as conductive fillers. The post-print activation of additive manufactured electrodes from this material is optimised and shown to produce enhanced electrochemical performance compared to non-activated electrodes, with a k0 of 1.03×10−3 cm s−1. The sterilisation for the real application of sensors in the biomedical field is a critical point, the electrodes were submitted to standard UV light treatment showing to be reliable compared to PLA in the determination of uric acid (30–500 µM) and sodium nitrite (0.1–5 mM) within synthetic urine using differential pulse voltammetry and chronoamperometry techniques. A sensitivity and LOD for uric acid of 25.7 µA µM−1 and 0.27 µM, and 52.6 µA mM−1 and 2.69 µM for nitrite were obtained within synthetic urine, respectively. The re-useability of the electrodes was also tested for the detection of uric acid, showing that the electrode could be used up to 10 times before a significant decrease in the results was observed. We demonstrate that a new conductive rPETg with superior electrochemical performance has a prominent place within the development of additive manufactured-printed healthcare sensors due to its ability to be sterilised and re-used, low solution ingress, and its potential to tackle rising costs and plastic waste problems within the healthcare sector