This manuscript provides the first report of a fully additively manufactured (AM) electrochemical cell printed all-in-one, where all the electrodes and cell are printed as one, requiring no postassembly or external electrodes. The three-electrode cell is printed using a standard non-conductive poly(lactic acid) (PLA)-based filament for the body and commercially available conductive carbon black/PLA (CB/ PLA, ProtoPasta) for the three electrodes (working, counter, and reference; WE, CE, and RE, respectively). The electrochemical performance of the cell is evaluated first against the well-known nearideal outer-sphere redox probe hexaamineruthenium(III) chloride (RuHex), showing that the cell performs well using an AM electrode as the pseudo-RE. Electrochemical activation of the WE via chronoamperometry and NaOH provides enhanced electrochemical performances toward outer-sphere probes and for electroanalytical performance. It is shown that this activation can be completed using either an external commercial Ag|AgCl RE or through simply using the internal AM CB/PLA pseudo-RE and CE. This all-inone electrochemical cell (AIOEC) was applied toward the well-known detection of ascorbic acid (AA) and acetaminophen (ACOP), achieving linear trends with limits of detection (LODs) of 13.6 ± 1.9 and 4.5 ± 0.9 μM, respectively. The determination of AA and ACOP in real samples from over-the-counter effervescent tablets was explored, and when analyzed individually, recoveries of 102.9 and 100.6% were achieved against UV−vis standards, respectively. Simultaneous detection of both targets was also achieved through detection in the same sample exhibiting 149.75 and 81.35% recoveries for AA and ACOP, respectively. These values differing from the originals are likely due to electrode fouling due to the AA oxidation being a surface-controlled process. The cell design produced herein is easily tunable toward different sample volumes or container shapes for various applications among aqueous electroanalytical sensing; however, it is a simple example of the capabilities of this manufacturing method. This work illustrates the next step in research synergising AM and electrochemistry, producing operational electrochemical sensing platforms in a single print, with no assembly and no requirements for exterior or commercial electrodes. Due to the flexibility, low-waste, and rapid prototyping of AM, there is scope for this work to be able to span and impact a plethora of research areas.

The recycling of post-industrial waste poly(lactic acid) (PI-PLA) from coffee machine pods into electroanalytical sensors for the detection of caffeine in real tea and coffee samples is reported herein. The PI-PLA is transformed into both nonconductive and conductive filaments to produce full electroanalytical cells, including additively manufactured electrodes (AMEs). The electroanalytical cell was designed utilizing separate prints for the cell body and electrodes to increase the recyclability of the system. The cell body made from nonconductive filament was able to be recycled three times before the feedstock-induced print failure. Three bespoke formulations of conductive filament were produced, with the PI-PLA (61.62 wt %), carbon black (CB, 29.60 wt %), and poly(ethylene succinate) (PES, 8.78 wt %) chosen as the most suitable for use due to its equivalent electrochemical performance, lower material cost, and improved thermal stability compared to the filaments with higher PES loading and ability to be printable. It was shown that this system could detect caffeine with a sensitivity of 0.055 ± 0.001 μA μM–1, a limit of detection of 0.23 μM, a limit of quantification of 0.76 μM, and a relative standard deviation of 3.14% after activation. Interestingly, the nonactivated 8.78% PES electrodes produced significantly better results in this regard than the activated commercial filament toward the detection of caffeine. The activated 8.78% PES electrode was shown to be able to detect the caffeine content in real and spiked Earl Grey tea and Arabica coffee samples with excellent recoveries (96.7–102%). This work reports a paradigm shift in the way AM, electrochemical research, and sustainability can synergize and feed into part of a circular economy, akin to a circular economy electrochemistry.

Polymer Additive Manufacturing (AM), otherwise known as 3D printing, is becoming increasingly popular in the field of electrochemistry since it allows affordable, on-demand production of bespoke devices. Provided a suitably...

day life. However, managing the endof-life of plastic materials has become an increasingly urgent topic due to the reliance of most virgin plastics production on non-renewable resources like oil, and the significant, harmful effects that environmentally persistent waste plastic can have on the natural world. [1] Limiting these effects requires consumption of virgin plastic to be reduced wherever possible, and where not possible, plastic waste should be recycled into new products such that it does not enter traditional waste streams (e.g., by being sent to landfill). With regards to plastics recycling, the ideal situation is one in which innovation facilitates "upcycling" of plastic waste into products that retain high value and longevity, such that the material flow from raw material to waste product is slowed significantly. [2] Seeking upcycling in this way can be especially effective when incorporated into Circular Economy (CE) practices; [2] while the precise definition of CE has not been formalized, in broad terms, it is a new economic model intended to cause a sea change in the way society approaches sustainable development. [3] Additive Manufacturing (AM), otherwise known as 3D

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