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6CCVD Research

Conductive printable electrodes tuned by boron-doped nanodiamond foil additives for nitroexplosive detection

At a Glance

Section titled “At a Glance”
MetadataDetails
Publication Date2022-07-05
JournalMicrochimica Acta
AuthorsAnna Dettlaff, MichaƂ Rycewicz, Mateusz Ficek, Aleksandra WieloszyƄska, Mateusz Szala
InstitutionsMilitary University of Technology in Warsaw, GdaƄsk University of Technology
Citations17
AnalysisFull AI Review Included

Executive Summary

Section titled “Executive Summary”

This research presents a novel, high-performance electrochemical sensor fabricated by integrating boron-doped nanodiamond foil (NDF) onto 3D-printed graphene-poly(lactic acid) (G-PLA) electrodes.

  • Core Value Proposition: The method provides a simple, inexpensive, and fast way to create highly sensitive, flexible electrodes for environmental monitoring, specifically targeting nitroexplosive compounds (TNT).
  • Synergistic Interface: Thermal treatment during NDF transfer causes the melted G-PLA to reform its interface, mirroring the diamond flake morphology. This creates a rigid, mechanically stable diamond/graphene junction with enhanced local tunneling.
  • Enhanced Performance: The highly doped (10 k ppm B) NDF composites showed significantly enhanced electrochemical kinetics compared to bare G-PLA or low-doped NDFs.
  • TNT Detection: The optimized G-PLA-NDF-10 k-bottom electrode achieved a low Limit of Detection (LOD) of 87 ppb (0.383 ”M) for 2,4,6-trinitrotoluene (TNT).
  • Flexibility: Since diamond flakes are flexible and thin nanostructures can be bent up to 10%, this approach is suitable for flexible or wearable sensor applications.
  • Charge Transfer: The high boron doping (10 k ppm) and the presence of sp2 carbon phases at the NDF surface efficiently mediate charge transport across the electrode/electrolyte interface.

Technical Specifications

Section titled “Technical Specifications”
ParameterValueUnitContext
Limit of Detection (LOD)87ppbTNT detection (G-PLA-NDF-10 k-bottom)
Linear Range0.064 - 64ppmTNT concentration range
Sensitivity1.290 ± 0.006”A ”M-1 cm-2TNT detection (G-PLA-NDF-10 k-bottom)
HET Rate Constant (k°)6.1 x 10-2cm s-1Fastest kinetics (G-PLA-NDF-10 k-top)
Charge Transfer Resistance (Rct)15Ω cm2G-PLA-NDF-10 k-bottom electrode
Effective Capacitance (Ceff)2.6 to 4”F cm-2Typical for diamond phase
NDF Boron Doping Level (High)10,000ppm ([B]/[C] ratio)Used for optimal sensor performance
NDF Boron Doping Level (Low)500ppm ([B]/[C] ratio)Used for comparison
3D Printer Nozzle Temperature220°CGraphene-PLA printing
3D Printer Bed Temperature60°CGraphene-PLA printing
NDF Transfer Temperature200°CThermal junction formation

Key Methodologies

Section titled “Key Methodologies”

The composite electrode fabrication involves three primary steps: NDF synthesis, G-PLA substrate printing, and thermal transfer/junction formation.

  1. Nanodiamond Foil (NDF) Synthesis:

    • NDFs were synthesized using Microwave Plasma Enhanced Chemical Vapor Deposition (MPECVD).
    • Boron doping levels were controlled at 500 ppm (0.5 k) and 10,000 ppm (10 k) [B]/[C] ratio.
    • Growth time was maintained at less than 300 minutes.
    • The NDFs exhibited low adhesion to the tantalum substrate, allowing for easy delamination and transfer.

  2. Graphene-Polymer Electrode Printing:

    • Electrodes were designed in CAD and printed using an Ender 3 Pro 3D printer.
    • A conductive graphene PLA filament (Black Magic 3D) was used as the substrate material.
    • Optimized printing parameters included a 0.5 mm nozzle, 220 °C nozzle temperature, 60 °C bed temperature, and 60 mm/s print speed with 100% infill density.

  3. Composite Electrode Fabrication (NDF Transfer):

    • The printed G-PLA electrode was heated to 200 °C on a hot plate.
    • The delaminated NDF foil was placed on the hot G-PLA surface using tweezers and pressed down with a tantalum substrate to ensure tight adhesion.
    • The thermal treatment induced PLA crystallinity transformation and improved homogeneity, while the melted G-PLA reformed its interface to match the diamond flake morphology, ensuring continuous electrical contact.
    • Both the top side (NDF-top) and reverse side (NDF-bottom) of the NDF were tested, with the NDF-bottom showing slightly better TNT detection performance.

  4. Electrochemical Testing:

    • Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS) were used to characterize kinetics using the K3[Fe(CN)6]/K4[Fe(CN)6] redox couple.
    • Differential Pulse Voltammetry (DPV) was used for TNT determination in 0.1 M phosphate buffer solution (pH = 6.8).

Commercial Applications

Section titled “Commercial Applications”

This technology, leveraging the unique properties of boron-doped diamond and 3D-printed conductive polymers, is highly relevant to several engineering and commercial sectors:

  • Environmental Monitoring: Inexpensive, fast field screening tests for contaminants of emerging concern (CEC), particularly nitroaromatic explosives (TNT, DNT, RDX) in aqueous environments.
  • Defense and Forensics: Development of portable, flexible, and wearable sensors for detecting explosive residues in the field, offering a low-cost alternative to time-consuming chromatographic analyses.
  • Flexible Electronics and Wearables: The use of flexible diamond thin nanostructures combined with 3D-printed polymer substrates allows for the creation of sensors that can be integrated into flexible devices or clothing.
  • Electrochemical Sensing Platforms: The highly conductive and chemically stable boron-doped diamond surface, combined with the customizable shape of 3D printing, provides a versatile platform for detecting various electroactive species (e.g., heavy metals, biomolecules).
  • Additive Manufacturing of Electrodes: The methodology provides a practical strategy for improving the electroanalytical response of standard 3D-printed graphene-PLA electrodes, enabling rapid prototyping and scaling of custom sensor geometries.
View Original Abstract

Abstract An efficient additive manufacturing-based composite material fabrication for electrochemical applications is reported. The composite is composed of commercially available graphene-doped polylactide acid (G-PLA) 3D printouts and surface-functionalized with nanocrystalline boron-doped diamond foil (NDF) additives. The NDFs were synthesized on a tantalum substrate and transferred to the 3D-printout surface at 200 °C. No other electrode activation treatment was necessary. Different configurations of low- and heavy-boron doping NDFs were evaluated. The electrode kinetics was analyzed using electrochemical procedures: cyclic voltammetry and electrochemical impedance spectroscopy. The quasi-reversible electrochemical process was reported in each studied case. The studies allowed confirmation of the CV peak-to-peak separation of 63 mV and remarkably high heterogeneous electron transfer rate constant reaching 6.1 × 10 −2 cm s −1 for 10 k ppm [B]/[C] thin NDF fitted topside at the G-PLA electrode. Differential pulse voltammetry was used for effective 2,4,6-trinitrotoluene (TNT) detection at the studied electrodes with a 87 ppb limit of detection, and wide linearity range between peak current density and the analyte concentration (0.064 to 64 ppm of TNT). The reported electrode kinetic differences originate primarily from the boron-dopant concentration in the diamond and the various contents of the non-diamond carbon phase. Graphical abstract

Tech Support

Section titled “Tech Support”

Original Source

Section titled “Original Source”

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