This study presents a rapid, environmentally friendly, and scalable activation method for 3D-printed poly-(lactic acid)/carbon black (PLA/CB) electrodes using atmospheric air plasma under ambient conditions. The goal was to optimize the plasma activation time and compare its efficiency with conventional activation techniques using N,N-dimethylformamide (DMF) and sodium hydroxide (NaOH). Surface morphology, chemical composition, wettability, and electrochemical performance were systematically evaluated through scanning electron microscopy (SEM), Raman spectroscopy, XPS, contact angle measurements, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). Plasma treatment, as short as 5 s, effectively removed the PLA matrix from the electrode surface, enhanced surface roughness, hydrophilicity, and exposure of conductive carbon black particles, leading to increased electrochemical performance. Compared to chemical activation, 40 s of plasma activation yielded comparable performance with significantly shorter processing times (vs NaOH) and without hazardous solvents (such as DMF). Finally, the activated electrodes were successfully applied in the development, optimization, and validation of a novel electrochemical protocol for the determination of the antihypertensive drug amlodipine, revealing high sensitivity, a low limit of detection of 0.09 μM, precision (RSD of 6.6%), and recovery (97.1 and 105.4%) in pharmaceutical formulations. The findings demonstrate the promising potential of air plasma activation as a sustainable and efficient approach for preparing 3D-printed electrodes for analytical and sensing applications.

• Publication type
• Journal Article MeSH

Commercially available conductive filaments are not designed for electrochemical applications, resulting in 3D printed electrodes with poor electrochemical behavior, restricting their implementation in energy and sensing technologies. The proper selection of an activation method can unlock their use in advanced applications. In this work, rectangular electrodes made from carbon black - polylactic acid (CB/PLA) filament are 3D printed with different layouts (grid and compact) and then activated using a highly reproducible eco-compatible electrochemical (EC) treatment. The electrodes are characterized for their morphological, structural, and electrochemical features to obtain insights into the material properties and functionality. Furthermore, the influence of the electrode layout as well as the activation conditions are studied aiming to provide a better understanding of the mechanism driving the electrochemical behavior of the electrodes. The EC activation enhances the electrochemical performance, provides a uniform electrochemical activity in the electrode's interface and allows the manipulation of the electrochemical properties of 3D printed electrodes by adjusting the duration of the treatment. CB/PLA electrodes offer a wide stable potential window that benefits their use in water-based electrochemical applications. Thus, their suitability for Zn-ion batteries and electrochemical sensing is explored, followed by their application in hydroquinone determination in water samples.

• Keywords
• 3D printed electrodes, aqueous battery, electrochemical activation, grid‐layout electrode, sensing,
• Publication type
• Journal Article MeSH

Surgical operations are intricate and invasive procedures that require continuous monitoring of the patient's biochemical profile. Point-of-care testing would allow healthcare professionals to identify abnormalities and make the necessary interventions to minimize the risk of complications and ensure patient safety. To this end, we report the development of a disposable and compact fully 3D-printed electrochemical cell incorporated into a medical scalpel (Lab-on-a-Scalpel), aiming to promote on-site (electro)chemical analysis in the operating theater. This multifunctional device minimizes the number of instruments needed during surgery and can be fabricated on-demand by using a desktop-sized 3D printer at a very low cost. The performance of the Lab-on-a-Scalpel sensing device was evaluated over various electrochemical techniques (cyclic voltammetry, amperometry, and differential pulse voltammetry) and different setups (stirring, drop-volume analysis, polarization potentials, etc.) for the determination of epinephrine. Results showed attractive analytical figures-of-merit, with the limit of detection (LOD) reaching 0.13 μM, and high accuracy in recovery studies conducted on artificial blood samples. Our findings suggest that Lab-on-a-Scalpel is a valuable tool that enables near-patient diagnostics with a minimum sample volume and holds promise to become an essential tool for robotic-assisted surgery.

• MeSH
• Printing, Three-Dimensional * MeSH
• Epinephrine * analysis   blood   MeSH
• Electrochemical Techniques * instrumentation   MeSH
• Lab-On-A-Chip Devices * MeSH
• Humans MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Epinephrine * MeSH

In this work, we pioneered the preparation of diamond-containing flexible electrodes using 3D printing technology. The herein developed procedure involves a unique integration of boron-doped diamond (BDD) microparticles and multi-walled carbon nanotubes (CNTs) within a flexible polymer, thermoplastic polyurethane (TPU). Initially, the process for the preparation of homogeneous filaments with optimal printability was addressed, leading to the development of two TPU/CNT/BDD composite electrodes with different CNT:BDD weight ratios (1:1 and 1:2), which were benchmarked against a TPU/CNT electrode. Scanning electron microscopy revealed a uniform distribution of conductive fillers within the composite materials with no signs of clustering or aggregation. Notably, increasing the proportion of BDD particles led to a 10-fold improvement in conductivity, from 0.12 S m-1 for TPU/CNT to 1.2 S m-1 for TPU/CNT/BDD (1:2). Cyclic voltammetry of the inorganic redox markers, [Ru(NH3)6]3+/2+ and [Fe(CN)6]3-/4-, also revealed a reduction in peak-to-peak separation (ΔE p) with a higher BDD content, indicating enhanced electron transfer kinetics. This was further confirmed by the highest apparent heterogeneous electron transfer rate constants (k 0 app) of 1 × 10-3 cm s-1 obtained for both markers for the TPU/CNT/BDD (1:2) electrode. Additionally, the functionality of the flexible TPU/CNT/BDD electrodes was successfully validated by the electrochemical detection of dopamine, a complex organic molecule, at millimolar concentrations by using differential pulse voltammetry. This proof-of-concept may accelerate development of highly desirable diamond-based flexible devices with customizable geometries and dimensions and pave the way for various applications where flexibility is mandated, such as neuroscience, biomedical fields, health, and food monitoring.

• Publication type
• Journal Article MeSH

Fused deposition modeling 3D printing (FDM-3DP) employing electrically conductive filaments has recently been recognized as an exceptionally attractive tool for the manufacture of sensing devices. However, capabilities of 3DP electrodes to measure electric properties of materials have not yet been explored. To bridge this gap, we employ bimaterial FDM-3DP combining electrically conductive and insulating filaments to build an integrated platform for sensing conductivity and permittivity of liquids by impedance measurements. The functionality of the device is demonstrated by measuring conductivity of aqueous potassium chloride solution and bottled water samples and permittivity of water, ethanol, and their mixtures. We further implement an original idea of applying impedance measurements to investigate dimensions of 3DP channels as base structures of microfluidic devices, complemented by their optical microscopic analysis. We demonstrate that FDM-3DP allows the manufacture of microchannels of width down to 80 μm.

• MeSH
• Printing, Three-Dimensional MeSH
• Potassium Chloride MeSH
• Ethanol MeSH
• Microfluidics * MeSH
• Drinking Water * MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Potassium Chloride MeSH
• Ethanol MeSH
• Drinking Water * MeSH

Additive manufacturing technology, referred as 3D printing technology, is a growing research field with broad applications from nanosensors fabrication to 3D printing of buildings. Nowadays, the world is dealing with a pandemic and requires the use of simple sensing systems. Here, the strengths of fast screening by a lab-on-a-chip device through electrochemical detection using 3D printing technology for SARS-CoV-2 sensing are combined. This system comprises a PDMS microfluidic channel integrated with an electrochemical cell fully 3D-printed by a 3D printing pen (3D-PP). The 3D-PP genosensor is modified with an ssDNA probe that targeted the N gene sequence of SARS-CoV-2. The sensing mechanism relies on the electro-oxidation of adenines present in ssDNA when in contact with SARS-CoV-2 RNA. The hybridization between ssDNA and target RNA takes a place and ssDNA is desorbed from the genosensor surface, causing a decrease of the sensor signal. The developed SARS-CoV-2/3D-PP genosensor shows high sensitivity and fast response.

• Keywords
• additive manufacturing, electroanalysis, lab on chip, nucleic acid,
• Publication type
• Journal Article MeSH