Novel Screen-Printed Sensor with Chemically Deposited Boron-Doped Diamond Electrode - Preparation, Characterization, and Application

At a Glance

Metadata	Details
Publication Date	2022-04-13
Journal	Biosensors
Authors	Oleksandr Matvieiev, Renáta Šelešovská, Marián Vojs, Marián Marton, Pavol Michniak
Institutions	Palacký University Olomouc, University of Pardubice
Citations	29
Analysis	Full AI Review Included

Executive Summary

This research details the fabrication and characterization of a novel, low-cost screen-printed sensor utilizing a chemically deposited Boron-Doped Diamond Electrode (SP/BDDE).

Hybrid Technology: The sensor combines the mass-production advantages of screen printing with the superior electrochemical properties of BDDE, fabricated using a Large-Area Linear Antenna Microwave Chemical Vapor Deposition (LA-MWCVD) system.
Material Quality: The BDD film was grown at 590 °C for 30 hours, resulting in a sub-microcrystalline film (~3.5 µm thick) with high electrical conductivity (resistivity 1.7 x 10^-2 Ω.cm).
Electrochemical Performance: The sensors exhibited a wide usable potential window (greater than 3000 mV) and excellent reversibility for outer-sphere redox markers ([Ru(NH₃)₆]^2+/3+), comparable to bulk BDDEs.
Analytical Application: The sensors were successfully applied for the determination of the anti-inflammatory drug Lornoxicam (LRX) using Differential Pulse Voltammetry (DPV).
High Sensitivity: The best laboratory-made sensor (3LM-SP/BDDE) achieved a Limit of Detection (LOD) for Lornoxicam of 9 x 10^-8 mol L^-1.
Repeatability: The novel LM-SP/BDDEs demonstrated very good inter-electrode repeatability (RSD₅ less than 5.1%), confirming their suitability for disposable sensor applications.
Mechanism Elucidation: The electrochemical oxidation mechanism of Lornoxicam was investigated using online EC-MS, identifying nine distinct reaction steps and corresponding products.

Technical Specifications

Parameter	Value	Unit	Context
BDD Deposition System	Cube 300 (LA-MWCVD)	N/A	Scia Ltd.
Microwave Power	6	kW	BDD Deposition
Substrate Temperature	590	°C	BDD Deposition
Chamber Pressure	30	Pa	BDD Deposition
Growth Time	30	h	BDD Film
BDD Film Thickness	~3.5	µm	Cross-section view
Gas Phase B/C Ratio	312,500	ppm	TMBT/CO₂/H₂ mixture
Electrically Active Boron Conc.	2.9 x 10²¹	cm^-3	Hall Measurement
Electrical Resistivity	1.7 x 10^-2	Ω.cm	Hall Measurement
Usable Potential Window (3LM-SP/BDDE)	3030	mV	0.1 mol L^-1 H₂SO₄
Charge Transfer Resistance (3LM-SP/BDDE)	2.4	kΩ	[Fe(CN)₆]^4-/3- inner sphere marker
Apparent Rate Constant (3LM-SP/BDDE)	1.42 x 10^-3	cm s^-1	[Fe(CN)₆]^4-/3-
Lornoxicam Limit of Detection (3LM-SP/BDDE)	9 x 10^-8	mol L^-1	DPV in Britton-Robinson buffer (pH 3)
Inter-Electrode Repeatability (3LM-SP/BDDE)	4.9	% (RSD₅)	Lornoxicam analysis

Key Methodologies

The novel screen-printed sensors (LM-SP/BDDE) were fabricated using a hybrid approach combining chemical vapor deposition and screen-printing technologies on a ceramic substrate.

BDDE Chemical Deposition (Working and Counter Electrodes):
- A linear antenna Microwave Chemical Vapor Deposition (LA-MWCVD) reactor was used.
- Deposition parameters included 6 kW microwave power, 590 °C substrate temperature, and 30 Pa pressure.
- The precursor gas mixture was H₂, 1% Trimethyl Borate (TMBT), and 0.2% CO₂, resulting in a gas phase B/C ratio of 312,500 ppm.
- The resulting BDD film was sub-microcrystalline with a thickness of approximately 3.5 µm.
Silver Electrode Printing (Reference Electrode and Contacts):
- The silver layer was printed onto the ceramic substrate using a screen-printing technique with AST6025 paste and a polyester mesh (71 threads cm^-1).
- Two layers were printed wet-on-wet, followed by drying at 150 °C for 30 minutes.
Reference Electrode (RE) Formation:
- The printed silver layer was transformed into Ag | AgCl quasi reference electrode via chronoamperometry (chlorination process).
- A voltage of +700 mV was applied for 30 seconds in a constantly stirred 0.1 mol L^-1 KCl solution.
Insulation Layer Application:
- A silicone-based screen-printing paste (240-SB) was used to define the electrode areas.
- Two layers were printed wet-on-wet using a polyester mesh (32 threads cm^-1).
- The layer was dried at 150 °C for 120 minutes.
Electrochemical Characterization:
- Sensors were characterized using Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS) with inner sphere ([Fe(CN)₆]^4-/3-) and outer sphere ([Ru(NH₃)₆]^2+/3+) redox probes.
- Lornoxicam analysis was performed using optimized Differential Pulse Voltammetry (DPV) in Britton-Robinson buffer (pH 3).

Commercial Applications

The development of stable, high-performance, and disposable BDDE sensors opens up significant opportunities in fields requiring rapid, low-cost, and reliable electrochemical analysis.

Point-of-Care (POC) Diagnostics: The disposable nature and tailored design of the screen-printed format are ideal for rapid, on-site analysis of biological samples (e.g., body fluids) for drug monitoring (as demonstrated with Lornoxicam) and biomarker detection.
Pharmaceutical Quality Control: High sensitivity and wide linear dynamic range (LDR) allow for accurate determination of active pharmaceutical ingredients (APIs) in complex dosage forms (verified using XefoRapid tablets).
Environmental Monitoring: BDDE’s wide potential window and resistance to passivation make these sensors suitable for long-term, on-line monitoring of electrochemically active pollutants, pesticides, and health-hazardous substances in harsh environments or flow systems.
Food Safety and Agriculture: Potential use in screening for contaminants, toxins, or specific biologically active compounds (BACs) in food and agricultural products, replacing expensive spectrometric methods.
Reusable Sensor Systems: The excellent intra-electrode repeatability and stability observed suggest that, despite the low cost, the LM-SP/BDDEs can also be used as reusable sensors for long-term laboratory applications.

View Original Abstract

New screen-printed sensor with a boron-doped diamond working electrode (SP/BDDE) was fabricated using a large-area linear antenna microwave chemical deposition vapor system (LA-MWCVD) with a novel precursor composition. It combines the advantages of disposable printed sensors, such as tailored design, low cost, and easy mass production, with excellent electrochemical properties of BDDE, including a wide available potential window, low background currents, chemical resistance, and resistance to passivation. The newly prepared SP/BDDEs were characterized by scanning electron microscopy (SEM) and Raman spectroscopy. Their electrochemical properties were investigated by cyclic voltammetry and electrochemical impedance spectroscopy using inner sphere ([Fe(CN)6]4−/3−) and outer sphere ([Ru(NH3)6]2+/3+) redox probes. Moreover, the applicability of these new sensors was verified by analysis of the anti-inflammatory drug lornoxicam in model and pharmaceutical samples. Using optimized differential pulse voltammetry in Britton-Robinson buffer of pH 3, detection limits for lornoxicam were 9 × 10−8 mol L−1. The oxidation mechanism of lornoxicam was investigated using bulk electrolysis and online electrochemical cell with mass spectrometry; nine distinct reaction steps and corresponding products and intermediates were identified.

Tech Support

Original Source

DOI: https://doi.org/10.3390/bios12040241

References

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