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.