An Investigation Into The Use Of Surfactants In Powder Suspension Formulations for Fingermark Development

Clover Ree, Lumikki

An Investigation Into The Use Of Surfactants In Powder Suspension Formulations for Fingermark Development

Clover Ree, Lumikki

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Publication Type:: Thesis
Issue Date:: 2025

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Field	Value	Language
dc.contributor.author	Clover Ree, Lumikki
dc.date.accessioned	2025-11-04T00:52:18Z
dc.date.available	2025-11-04T00:52:18Z
dc.date.issued	2025
dc.identifier.uri	http://hdl.handle.net/10453/190608
dc.description	University of Technology Sydney. Faculty of Science.	en_US.UTF-8
dc.description.abstract	Significant research has been conducted to improve fingermark development techniques, yet a limited understanding of their underlying mechanisms hinders further advancement. One such technique, iron oxide powder suspensions (FePS), is recommended for fingermark development on wetted non-porous surfaces but may have broader applications. This study aimed to improve mechanistic understanding of FePS by investigating the role of surfactants in fingermark development. A comprehensive assessment of surfactant types, concentrations, and ratios was conducted on non-porous surfaces. Surfactant performance varied, with non-ionic surfactants—specifically Tween 20 and Kodak Photo-Flo—proving most effective at a powder-to-surfactant ratio of 1:2. In contrast, formulations using only water and powder showed high background deposition, indicating that surfactants are critical for selective powder adherence. Performance also differed by substrate, with plastic showing reduced powder adhesion, suggesting surface chemistry plays a large role in development efficacy. The importance of micelle presence and structure was then investigated and shown to be vital for successful fingermark development. Continuing variation between surfactants demonstrated that micelle structure also influences development quality. Effective surfactants were sufficiently stable to prevent background deposition yet still be sensitive enough to fingermark residue components to allow for on-ridge deposition. Analysis of the chemical structures of assessed surfactants determined that optimal surfactants contained between 8 to 12 carbons in the surfactant tail, however the size and complexity of these structures did not appear to influence development. Importantly, surfactants had specific concentrations at which they were effective in FePS and therefore cannot be used interchangeably at the same concentrations. Artificial fingermark simulants were used to explore interactions between surfactants and fingermark residue components. Although not fully representative of natural residue, the simulants revealed that surfactants influence sensitivity to different compound classes. Development success depended on a nuanced interaction between eccrine and sebaceous materials, shaped by the choice of surfactant. Even when no visual residue remained under phase contrast microscopy, successful development could still occur—particularly for eccrine-rich deposits—suggesting that previous failures may have been due to unstable formulations rather than residue absence. This study highlights the critical role of surfactants in the FePS technique, revealing key factors that influence development success, including micelle behaviour, substrate surface chemistry, and residue interaction. As surfactants are used in other detection methods, these findings may inform broader fingermark development research. Overall, this work underscores the need for continued exploration of the chemical interactions underpinning fingermark development.	en_US.UTF-8
dc.format	Thesis (PhD)
dc.language.iso	en_US	en_US.UTF-8
dc.relation	https://opus.lib.uts.edu.au/bitstream/10453/190608/3/thesis.pdf
dc.rights	info:eu-repo/semantics/openAccess
dc.rights	The author owns the copyright in this thesis including all reproduction and reuse rights for the work. The work may not be altered without the permission of the copyright owner. Attribution is essential when quoting or paraphrasing from this thesis.
dc.rights	© 2025 Lumikki Clover Ree
dc.rights	au.edu.uts.lib/cph
dc.title	An Investigation Into The Use Of Surfactants In Powder Suspension Formulations for Fingermark Development	en_US.UTF-8
dc.type	Thesis
utslib.copyright.status	open_access	*

Abstract:

Significant research has been conducted to improve fingermark development techniques, yet a limited understanding of their underlying mechanisms hinders further advancement. One such technique, iron oxide powder suspensions (FePS), is recommended for fingermark development on wetted non-porous surfaces but may have broader applications. This study aimed to improve mechanistic understanding of FePS by investigating the role of surfactants in fingermark development. A comprehensive assessment of surfactant types, concentrations, and ratios was conducted on non-porous surfaces. Surfactant performance varied, with non-ionic surfactants—specifically Tween 20 and Kodak Photo-Flo—proving most effective at a powder-to-surfactant ratio of 1:2. In contrast, formulations using only water and powder showed high background deposition, indicating that surfactants are critical for selective powder adherence. Performance also differed by substrate, with plastic showing reduced powder adhesion, suggesting surface chemistry plays a large role in development efficacy. The importance of micelle presence and structure was then investigated and shown to be vital for successful fingermark development. Continuing variation between surfactants demonstrated that micelle structure also influences development quality. Effective surfactants were sufficiently stable to prevent background deposition yet still be sensitive enough to fingermark residue components to allow for on-ridge deposition. Analysis of the chemical structures of assessed surfactants determined that optimal surfactants contained between 8 to 12 carbons in the surfactant tail, however the size and complexity of these structures did not appear to influence development. Importantly, surfactants had specific concentrations at which they were effective in FePS and therefore cannot be used interchangeably at the same concentrations. Artificial fingermark simulants were used to explore interactions between surfactants and fingermark residue components. Although not fully representative of natural residue, the simulants revealed that surfactants influence sensitivity to different compound classes. Development success depended on a nuanced interaction between eccrine and sebaceous materials, shaped by the choice of surfactant. Even when no visual residue remained under phase contrast microscopy, successful development could still occur—particularly for eccrine-rich deposits—suggesting that previous failures may have been due to unstable formulations rather than residue absence. This study highlights the critical role of surfactants in the FePS technique, revealing key factors that influence development success, including micelle behaviour, substrate surface chemistry, and residue interaction. As surfactants are used in other detection methods, these findings may inform broader fingermark development research. Overall, this work underscores the need for continued exploration of the chemical interactions underpinning fingermark development.

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