Applicability of Selected 3D Printing Materials in Electrochemistry

Pencil graphite electrodes for in-situ spectroelectrochemical sensing of reaction intermediates and products in organic solvents

BACKGROUND

Spectroelectrochemistry (SEC) is a valuable analytical tool providing insights to reaction mechanisms and the structure of species involved in charge transfer reactions. Most of commercial SEC setups are based on platinum working electrodes where the adsorption of species involved in reactions often complicates their analysis.

RESULTS

In this work, we employ an array of pencil graphite rods as an optically transparent working electrode in a custom-made air-tight thin-layer cell suitable for the SEC analysis performed here in acetonitrile as a representative non-aqueous solvent. The functionality of the device was demonstrated by UV-Vis SEC sensing of charge transfer reactions of ruthenium acetylacetonate, ferrocene and ethylviologen dibromide redox probes performed employing the cyclic voltammetry. The SEC response obtained for all three probes confirmed no adsorption and the absence of oxygen in the cell. Furthermore, we have developed and utilized finite element method numerical simulations considering charge transfer reactions coupled with the diffusional mass transport to model the cyclic voltammetric response and the reaction conversion in the thin-layer SEC cell.

SIGNIFICANCE

Our work paves the way for easy-to-assemble customized air-tight adsorption-free SEC devices with the manufacturing costs well below those of commercially available platforms. Developed computational approaches have the predictive power for optimizing reaction conditions and the geometry of the SEC cell.

3D Printed Fused Deposition Modeling (FDM) Capillaries for Chemiresistive Gas Sensors

This paper discusses the possible use of 3D fused deposition modeling (FDM) to fabricate capillaries for low-cost chemiresistive gas sensors that are often used in various applications. The disadvantage of these sensors is low selectivity, but 3D printed FDM capillaries have the potential to increase their selectivity. Capillaries with 1, 2 and 3 tiers with a length of 1.5 m, 3.1 m and 4.7 m were designed and manufactured. Food and goods available in the general trade network were used as samples (alcohol, seafood, chicken thigh meat, acetone-free nail polish remover and gas from a gas lighter) were also tested. The "Vodka" sample was used as a standard for determining the effect of capillary parameters on the output signal of the MiCS6814 sensor. The results show the shift of individual parts of the signal in time depending on the parameters of the capillary and the carrier air flow. A three-tier capillary was chosen for the comparison of gas samples with each other. The graphs show the differences between individual samples, not only in the height of the output signal but also in its time characteristic. The tested 3D printed FDM capillaries thus made it possible to characterize the output response by also using an inexpensive chemiresistive gas sensor in the time domain.

Circular Economy Electrochemistry: Recycling Old Mixed Material Additively Manufactured Sensors into New Electroanalytical Sensing Platforms

Recycling used mixed material additively manufactured electroanalytical sensors into new 3D-printing filaments (both conductive and non-conductive) for the production of new sensors is reported herein. Additively manufactured (3D-printed) sensing platforms were transformed into a non-conductive filament for fused filament fabrication through four different methodologies (granulation, ball-milling, solvent mixing, and thermal mixing) with thermal mixing producing the best quality filament, as evidenced by the improved dispersion of fillers throughout the composite. Utilizing this thermal mixing methodology, and without supplementation with the virgin polymer, the filament was able to be cycled twice before failure. This was then used to process old sensors into an electrically conductive filament through the addition of carbon black into the thermal mixing process. Both recycled filaments (conductive and non-conductive) were utilized to produce a new electroanalytical sensing platform, which was tested for the cell's original application of acetaminophen determination. The fully recycled cell matched the electrochemical and electroanalytical performance of the original sensing platform, achieving a sensitivity of 22.4 ± 0.2 μA μM^-1, a limit of detection of 3.2 ± 0.8 μM, and a recovery value of 95 ± 5% when tested using a real pharmaceutical sample. This study represents a paradigm shift in how sustainability and recycling can be utilized within additively manufactured electrochemistry toward promoting circular economy electrochemistry.

Application of three dimensional-printed devices in extraction technologies

Sample pretreatment is an important and necessary process in chemical analysis. Traditional sample preparation methods normally consume moderate to large quantities of solvents and reagents, are time- and labor-intensive and can be prone to error (since they usually involve multiple steps). In the past quarter century or so, modern sample preparation techniques have evolved, from the advent of solid-phase microextraction and liquid-phase microextraction to the present day where they are now widely applied to extract analytes from simple as well as complex matrices leveraging on their extremely low solvent consumption, high extraction efficiency, generally straightforward and simple operation and integration of most, if not all, of the following aspects: Sampling, cleanup, extraction, preconcentration and ready-to-inject status of the final extract. One of the most interesting features of the progress of microextraction techniques over the years lies in the development of devices, apparatus and tools to facilitate and improve their operations. This review explores the application of a recent material fabrication technology that has been receiving a lot of interest, that of three-dimensional (3D) printing, to the manipulation of microextraction. The review highlights the use of 3D-printed devices in the extraction of various analytes and in different methods to address, and improves upon some current extraction (and microextraction) problems, issues and concerns.