Abstract
For this paper, a fully integrated and highly miniaturized electrochemical sensor was designed and fabricated on a silicon substrate. A solvothermal-assisted reduced graphene oxide named “TRGO” was then successfully micro-patterned using a lithography technique, followed by the electrodeposition of bismuth (Bi) on the surface of the micro-patterned TRGO for the electrochemical detection of heavy metal ions. The fully integrated electrochemical micro-sensor was then measured and evaluated for the detection of cadmium and lead-heavy metal ions in an acetic-acid buffered solution using the square wave anodic stripping voltammetry (SWASV) technique. The fabricated micro-sensor exhibited a linear detection range of 1.0 μg L−1 to 120.0 μg L−1 for both of the metal ions, and detection limits of 0.4 μg L−1 and 1.0 μg L−1 were recorded for the lead and cadmium (S/N = 3), respectively. Drinking-water samples were used for the practical assessment of the fabricated micro-sensor, and it showed an acceptable detection performance regarding the metal ions.
Highlights
In most cases, mercury-film electrodes are preferred for their excellent stripping characteristics in heavy metal ions recognition
The TRGO was patterned in macro-scale on the top of the working electrode using the thick photoresist as a sacrificial layer
The sound film-forming ability of TRGO facilitates large surface coverage on the substrate, which is suitable for the large-scale production of TRGO
Summary
Mercury-film electrodes are preferred for their excellent stripping characteristics in heavy metal ions recognition. A large amount of work has been undertaken regarding electrode-surface modifications to increase the sensitivity of metal-detection methods[10,11,12,13]. Among these works, the graphene-material-based working electrode has emerged as a promising alternative due to its unique thermal, mechanical, and electrochemical properties[14]. A simple and reliable micro-fabrication process is developed for the micro-patterning of TRGO film without affecting the electrochemical property of the film. After in situ deposition of the bismuth film on the working TRGO/ Au electrode, a fully integrated heavy metal ions sensor with three electrodes is developed and characterized using SWASV. It provides quick response and full device integration on various substrates
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