New carbon black-based conductive filaments for the additive manufacture of improved electrochemical sensors by fused deposition modeling

Abstract

The development of a homemade carbon black composite filament with polylactic acid (CB-PLA) is reported. Optimized filaments containing 28.5% wt. of carbon black were obtained and employed in the 3D printing of improved electrochemical sensors by fused deposition modeling (FDM) technique. The fabricated filaments were used to construct a simple electrochemical system, which was explored for detecting catechol and hydroquinone in water samples and detecting hydrogen peroxide in milk. The determination of catechol and hydroquinone was successfully performed by differential pulse voltammetry, presenting LOD values of 0.02 and 0.22 µmol L^-1, respectively, and recovery values ranging from 91.1 to 112% in tap water. Furthermore, the modification of CB-PLA electrodes with Prussian blue allowed the non-enzymatic amperometric detection of hydrogen peroxide at 0.0 V (vs. carbon black reference electrode) in milk samples, with a linear range between 5.0 and 350.0 mol L^-1 and low limit of detection (1.03 µmol L^-1). Thus, CB-PLA can be successfully applied as additively manufactured electrochemical sensors, and the easy filament manufacturing process allows for its exploration in a diversity of applications.

Keywords: 3D-printed sensors; Carbon black; Composite filament fabrication; Differential pulse voltammetry; Non-enzymatic detection; Prussian blue.

Fig. 1

Representative scheme of the experimental procedure: a Fabrication of CB-PLA conductive filament. b Obtention of electrochemical cell design and 3D printing preparation. c Image of the electrochemical cell and electrodes. d Scheme of PB electrochemical modification

Fig. 2

a Thermogravimetric analysis for CB-PLA filaments of different carbon black loadings (5.0 to 30.0% wt.). b Cyclic voltammograms recorded for 1.0 mmol L⁻¹ ferrocene methanol in 0.1 mol L⁻¹ KCl, using CB-PLA 3D-printed electrodes obtained from the lab-made filaments with different carbon black loadings (from 20.0 to 30.0% wt.), and respective blank solutions (0.1 mol L⁻¹ KCl—dotted lines). c Cyclic voltammograms recorded for 1.0 mmol L⁻¹ ferrocene methanol in 0.1 mol L⁻¹ KCl, using CB-PLA 3D printed electrodes obtained from the lab-made filaments containing 28.5% wt. carbon black, or commercial Proto-pasta filaments, both before and after electrochemical treatment. Dotted lines correspond to the blank solution. d Raman spectra for 3D-printed electrodes obtained with Proto-pasta and CB-PLA 28.5% wt. before and after electrochemical surface treatment

Fig. 3

SEM images for a Proto-pasta 3D-printed electrodes, b Proto-pasta 3D-printed electrodes after electrochemical surface treatment, c CB-PLA (28.5% wt. carbon black), and d CB-PLA (28.5% wt. carbon black) after electrochemical surface treatment, with amplification factors of 5000 × . Inset: respective contact angle images

Fig. 4

Cyclic voltammograms recorded for 1.0 mmol L⁻¹ a catechol; b hydroquinone using CB-PLA 3D-printed electrodes before (black line) and after (blue line) electrochemical surface treatment, and respective schematic representation of the redox mechanism for c catechol and d hydroquinone. Scan rate: 50 mV s⁻¹; Supporting electrolyte: 0.1 mol L⁻¹ phosphate buffer solution (pH = 7.4); Dotted lines: respective blank solution

Fig. 5

DPV recordings for increasing concentrations of catechol (a) and hydroquinone (c), and respective analytical curves (b) and (d), obtained at the electrochemically treated CB-PLA 3D printed electrode; supporting electrolyte: 0.1 mol L⁻.¹ phosphate buffer solution (pH 7.4)

Fig. 6

SEM images of CB-PLA after electrochemical surface treatment before (a), and after Prussian blue electrodeposition—PB/CB-PLA (b), with amplification factors of 5000 x. c Cyclic voltammograms were obtained in 0.1 mol L⁻¹ phosphate buffer solution (pH 7.4) containing 0.1 mol L⁻¹ KCl at CB-PLA after modification with PB. Scan rate: 50 mV s⁻.¹

Fig. 7

Cyclic voltammograms recorded for 1.0 mmol L⁻¹ hydrogen peroxide using a PB modified CB-PLA 3D-printed electrode (a), before (black line) and after (blue line) electrochemical surface treatment. Scan rate: 50 mV s⁻¹; dotted lines: respective blank solution, and b amperometric responses (n = 3) for increasing concentrations of H₂O₂. Supporting electrolyte: 0.1 mol L⁻¹ phosphate buffer solution (pH 7.4) containing 0.1 mol L⁻¹ KCl; working potential: 0.0 V (vs. carbon black); inset: respective analytical curve