Surface analysis of Detonation Nanodiamond thin films fabricated using automated spray coating technique

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Journal Title
Journal ISSN
Volume Title
Sähkötekniikan korkeakoulu | Master's thesis
Date
2018-05-14
Department
Major/Subject
Translational Engineering
Mcode
ELEC3023
Degree programme
AEE - Master’s Programme in Automation and Electrical Engineering (TS2013)
Language
en
Pages
61+8
Series
Abstract
In recent years, Detonation Nanodiamond (DND) has gained importance as a biomaterial. DND can be made into thin film coating on substrates, which is a requirement for many bioanalytical sensing devices. In this work, the distribution and thickness of DND coated as thin film on silicon substrate were studied. The coating was performed using an automated spray coating device designed for thin film deposition. The spray coated samples were compared with samples fabricated by spin coating. Scanning Electron Microscopy (SEM) was used as the analysis tool to analyse the distribution and thickness of the thin film samples. DNDs were observed as densely packed agglomerates on the surface of the thin film coatings. Agglomeration causes the DND particles to form clusters resulting in unevenness of coating surface. To prevent agglomeration and improve evenness of coating, deagglomeration is carried out using ultrasonication. The core aggregates were left intact, and the smallest observable aggregates were no less than 10nm. The thickness of DND coated thin films was measured using SEM. Thickness measurements show the coating to be uneven, which is expected to occur due to agglomeration. The average thickness of spray coating samples lies between 450 – 550 nm and that of spin coated samples lie between 200-300 nm for the same amount of solution consumption per unit area. Delamination of DND coating from Silicon substrate occurred due to the intense grinding and polishing processes during sample preparation for SEM analysis, which decreases the evenness of coating and accuracy of measurements. Improved sample preparation methods are required to obtain accurate thickness measurement using SEM. Further improvements on deagglomeration techniques might improve the distribution of DND particles, and consistency of coating thickness in DND thin film coatings. SEM has resolution power in the nanometre scale making it a good analysis tool to measure the distribution of the thin film coatings. Nevertheless, it was not possible to observe primary DND particles with good resolution below 100 nm scale using SEM. SEM along with improved sample preparation methods could possibly be a good analysis tool for thickness measurements, as it is required to fabricate measurable and repeatable thin film coatings in industrial scale.
Description
Supervisor
Laurila, Tomi
Thesis advisor
Sainio, Sami
Keywords
detonation nanodiamond, thin film coatings, scanning electron microscopy, surface analysis, coating thickness
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Citation