Mixing of graphite
and carbon black (CB) alongside recycled
poly(lactic
acid) and castor oil to create an electrically conductive additive
manufacturing filament without the use of solvents is reported herein.
The additively manufactured electrodes (AMEs) were electrochemically
benchmarked against a commercial conductive filament and a bespoke
filament utilizing only CB. The graphite/CB produced a heterogeneous
rate constant, k
0, of 1.26 (±0.23)
× 10–3 cm s–1 and resistance
of only 155 ± 15 Ω, compared to 0.30 (±0.03) × 10–3 cm s–1 and 768 ± 96 Ω for the commercial AME.
Including graphite within the filament reduced the cost of printing
each AME from £0.09, with the CB-only filament, to £0.05.
The additive manufacturing filament was successfully used to create
an electroanalytical sensing platform for the detection of oxalate
within a linear range of 10–500 μM, achieving a sensitivity
of 0.0196 μA/μM, LOD of 5.7 μM and LOQ of 18.8 μM
was obtained. Additionally, the cell was tested toward the detection
of oxalate within a spiked synthetic urine sample, obtaining recoveries
of 104%. This work highlights how, using mixed material composites,
excellent electrochemical performance can be obtained at a reduced
material cost, while also greatly improving the sustainability of
the system.