Additive Manufacturing of a Portable Electrochemical Sensor with a Recycled Conductive Filament for the Detection of Atropine in Spiked Drink Samples

Abstract

Additive manufacturing (three-dimensional (3D) printing) has promising features for fast prototyping electrochemical systems, from cells to sensors. Conductive filaments containing carbon black and poly(lactic acid) (CB/PLA) for electrode fabrication are commercially available but usually rely on low carbon content, resulting in poor electrochemical properties. Filament fabrication can be done within the laboratory by exploring different materials according to the desired applications. In this work, recycled PLA was used as the thermoplastic base polymer, alongside CB as the conductive filler, and tris (2ethylhexyl) trimellitate was introduced into the filament matrix as a plasticizer (CB/PLA/ TTM) to fabricate additively manufactured electrodes (AMEs). This enhanced the electrochemical properties toward different redox probes and the forensic target atropine. Thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) were used to characterize the filament and AMEs before and after activation. Additive manufacturing has also been used to develop different cell configurations, which is equally important for good electroanalytical performance. Flow analytical techniques, such as batch-injection analysis (BIA), can be used as an alternative to stationary measurements to enhancing sensitivity and detection limits (LOD) via increasing the mass transport of analytes to the electrochemical platform surface, providing automation and high sample throughput. In this context, we developed a compact (∼5 mL capacity) and versatile additively manufactured BIA cell that can either perform static or hydrodynamic analyses by simply placing a lid on the device with a hole for the BIA pipette tip. Moreover, knowing that forensic chemistry necessitates portable analytical tools to help police investigation at the crime scene, the AM-BIA cell and the bespoke AMEs were coupled to a portable electrochemical apparatus for on-site atropine analysis in adulterated beverage samples. Atropine determination was performed by differential pulse voltammetry (DPV) and amperometry (BIA-AMP) in the same cell, presenting good repeatability for both methods (6% RSD). As expected, the BIA-AMP method showed higher sensitivity (0.0783 μA μM −1 ) and lower LOD (0.51 μM) compared to the stationary DPV method (sensitivity: 0.0148 μA μmol −1 L; LOD: 2.60 μM); they both presented good recovery values, varying from 102 to 109% for two spiked samples of gin and whisky. Thus, the versatility and portability of the developed AM-BIA cell coupled with the bespoke filament CB/PLA/TTM allow for rapid and accurate screening and quantification of atropine in real forensic scenarios.

Optimised graphite/carbon black loading of recycled PLA for the production of low-cost conductive filament and its application to the detection of β-estradiol in environmental samples

“…1 A, which demonstrates the excellent low-temperature flexibility of this filament. Across 10 cm of this filament, an extremely low average resistance of 277 ± 9 Ω was measured, which matches the published bespoke filament range from ~ 250 to 1000 Ω [ 26 – 28 , 39 ] and represents a significant improvement on the commercially available conductive PLA which has a quoted resistance of 2–3 kΩ [ 40 , 41 ]. Importantly, this filament achieves such a level of conductivity at a low material cost of under £0.06 per gram, compared to £0.72 per gram previously reported [ 27 ] and a current purchasing cost of commercial filament of ~£1.20 per gram.…”

Electroanalysis overview: additive manufactured biosensors using fused filament fabrication

“…The ability to make bespoke laments has received signicant attention, where one can vary the thermoplastic, for example into recycled versions, and one can change the conducting components and increase their amount, alongside the use of bio-based plasticizers. 11,[33][34][35]70 The approach to fabricate bespoke lament is summarized within Fig. 3, where two approaches have been developed, one that produces conductive composites using solvent-based methods, and another that employs thermal procedures.…”

“…These all aim to improve the electrochemical and printing performance over that achievable using commercially available laments, with many easily printable materials offering signicantly lower resistances (200-900 U over 10 cm of lament length). [32][33][34][35][36][37][38] In this minireview, we focus upon the use of FFF additive manufacturing technology along with the use of biosensors that are exclusively using antibodies, enzymes and associated biosensing materials (mediators). This minireview paper looks to provide an overview of the literature on the use of additive manufacturing for the production of electrochemical biosensors, with the focus on fused lament fabrication for the production of the electrode and offer some suggestions for how this eld can progress in the future.…”

“…These all aim to improve the electrochemical and printing performance over that achievable using commercially available filaments, with many easily printable materials offering significantly lower resistances (200–900 Ω over 10 cm of filament length). 32–38…”

Room Temperature Photocurable PEEK Polymer Formulations for High-Performance 3D Printing Applications

“…In diverse fields, 3D printing finds applications ranging from tissue engineering and medical device fabrication to soft robotics, dentistry, and sensor development among many others. − The methods used in 3D printing are classified based on printing techniques and material utilization. Extrusion-based 3D printing, including melt material extrusion (MME) and direct ink writing (DIW), is commonly employed for the fabrication of high-performance polymer (HPP) structures from filaments or shear thinning inks. − Photocuring technologies, such as stereolithography (SLA) and digital light processing (DLP), utilize photochemical curing of liquid acrylate or cationically polymerizable resin materials to produce 3D-printed components. , Compared to extrusion-based methods, DLP 3D printing offers higher precision in manufacturing, improved mechanical toughness, and better layer unity. , Despite these advancements, a persistent challenge lies in processing high-performance polymers (HPPs) such as polyether ether ketone (PEEK) and polyimide under ambient conditions. , HPPs exhibit remarkable mechanical and thermal properties due to the concentration of aromatic rings within their polymer chains, resulting in strong bonds and interchain interactions. , PEEK, in particular, stands out for its strength and heat resistance, making it valuable in fields like the automotive industry and medical implants. − Commercial PEEK polymer has a reported tensile strength of 90–100 MPa and Young’s modulus of 4 GPa with a glass transition temperature of 143 °C and stability up to 450 °C with only 5% weight loss.…”