Additively Manufactured Collector-Detector Device for Explosive Analysis Using Recycled PLA Filament Loaded with Carbon Black and Graphite
Maria M. C. Souza, Gilvana P. Siqueira, Raquel G. Rocha, Robert D. Crapnell, Mário H.P. Santana, Eduardo M. Richter, Craig E. Banks, Rodrigo A.A. Muñoz
Abstract
We report the electrochemical potential of conductive filaments produced with recycled polylactic acid (rPLA) alongside a mixture of graphite (Gpt) and/or carbon black (CB) and castor oil to create an electrode ready-to-use. Additively-manufactured electrodes (AMEs) were compared with commercial-conductive filament composed of PLA and CB. The Gpt-CB-rPLA and CB-rPLA sensors showed lower charge-transfer resistance (Rct) and a greater heterogenous rate constant, k0 , (Rct = 1040 ± 50 Ω and 1810 ± 30 Ω and k0 = 6.91 (± 0.58) ×10-3 and 5.31 (± 0.40) × 10-3 cm s-1, respectively) compared to the sensor from the commercial filament (Rct = 9620 ± 280 Ω and k0 = 3.62 (± 0.38) ×10-3 cm s-1). The electrochemical response of [Fe(CN6)]3-/4- displayed a peak-to-peak separation of 180 ± 8 mV (Gpt-CB-rPLA) and 240 ± 6 mV (CB-rPLA) compared to commercial AME (740 ± 10 mV), without any surface treatment. The filaments were used to create a 2,4,6-trinitrotoluene (TNT) detection platform with linear range of 5-20 and 5-100 µmol L-1 for Gpt-CB-rPLA and CB-rPLA, respectively. The collector-detector device was applied for the analysis of a blast simulation. Finally, it is worth noting that the results obtained are without electrode treatment/activation, indicating that the rough surface of the additively manufactured electrode is an additional feature of the device for collecting explosive residues, simply by rubbing the additively manufactured platform on different surfaces in crime scenarios.