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Personal profile

Area of academic expertise - outline

PECVD and Reactive Magnetron plasma sputtered thin films and coatings for biomedical, functional and engineering applications.

Current research activities

Biomaterials research: Several technologically important processes depend on the interaction at surfaces. Typical examples include the biocompatibility and haemocompatibility of artificial implant surfaces in vivo, specific and non-specific processes in bio-assays involving surface-analyte interactions and the interaction of dental materials with saliva. Lab-on-a-chip devices for DNA micro-array technologies and bio-chips for molecular detection involve microfluidic flows in micro-channels where a large surface to volume ratio exists. The fluid flow behaviour under these conditions will be dominated by a combination of capillary, thermocapillary, Maragoni, electrostatic and Van der Waals Forces. Any variations in surface properties or unsuitable substrate surface energies will lead to unstable fluidic conditions and prevent the desired rapid reaction and synthesis expected of microfluidic devices. Surface forces are also responsible for stiction in micro-electromechanical devices (MEMS), and the adhesion of microbes to the surface of cathethers, stents and filteration systems in waste-water treatment. Cell and protein adhesion to implant materials responsible for haemocompatibility and biocompatibility is also dependent on surfaces.

We are investigating the above and several other surface related phenomena through their dependence on three basic forces, namely, the Lifshitz-Van der Waals, Electrostatic and Acid-base interactions. The details of these interactions and their influence on the various surface phenomena described above are captured within the extended Derjaguin, Landau, Verwey and Overbeek (XDLVO) theory. We probe into these interactions through experimental measurements of the surface energies, hydrophobic and hydrophylic effects and Zeta potential measurements of surface charge conditions. The interactions of molecular absorbates, distribution of ions and surface forces are all affected by the nature of these surface charges. The Kelvin probe is also used to measure band bending and electron affinity variations and their role in surface interactions. The surface interactions are further monitored by AFM surface topography and force curve analysis. Our previous research has received support from industry including Vascutek and Lifescan Ltd.

                                                                 

Corrosion research and Energy storage materials: We are currently investigating films prepared by reactive magnetron sputtering with a range of stoichiometries selected to create a variation of their flat band potential and a flattening of the band-bending or band edge shift. The films are characterised by the Mott-Schottky analysis to determine their flat band changes. Electrochemical impedance spectroscopy based on Nyquist and Bode plots is used to monitor their corrosion resistance. The optical band gap of the films is monitored with the aid of a spectrophotometer and ellipsometry, whilst FTIR and Raman spectroscopy is used to measure film quality. The possible initiation sites for pitting in the films are monitored by scanning Kelvin probe. We also use cyclic voltammograms and galvanostatic charge/discharge investigations to probe the ability of thin films materials to act as supercapacitors for rapid storage and rapid discharge of energy for future advanced energy environments.

Our on-going activity in this area has generated interest from potential users due to the promise shown by the prepared films as potential corrosion coatings in marine and atmospheric (i.e. aqueous and non-aqueous) environments for the protection of engineering components from corrosion. The other potential applications of our plasma prepared films include pollutant decontamination in wastewater, applications in desalination plants and the production of hydrogen through the photochemical decomposition of water. We have received previous support from industry especially Thales Optronics, Glasgow, Scotland, UK.

Desired research direction

My research with my PhD students as well as collaborators within the U.K. and Overseas will continue to focus on both fundamental and applied aspects of functional thin films and coatings. We will continue to focus on the development of leading novel solutions to problems related to societal and economic needs and technological foresight projects. One of our recent research activity is being developed into a patentable bio-photonic product, with the promise of a substantial cost and time advantage in healthcare and associated environments. We will also continue to build on our international research partnerships with leading Universities and national laboratories in Europe, Asia and North America. We have continued to receive invitations to present keynote papers and chair sessions at major international scientific conferences, contribute chapters and lead the development of advanced scientific monographs published by globally leading scientific publishers as well as serving on the Editorial boards of international journals.

Target collaborative organisations

I have being a PI, co-PI and scientific investigator on projects funded by U.K. and international companies that include, Zedmark refractories, U.K.  Sandvik Coromat, Sweden, Seagate Technology, Ireland, Thales Optronics, U.K., Sub-one Inc., USA, ITI Energy, Lifescan, U.K, Vascutek Terumo, U.K., Qioptiqs U.K.. My research will continue to be in partnership with similar leading organisations. I have also recently set-up the UWS physics industrial advisory board to further engage the UWS physics research activities with industries including some of those listed above.

Fingerprint Dive into the research topics where Abraham Ogwu is active. These topic labels come from the works of this person. Together they form a unique fingerprint.

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Research Output 2008 2019

29 Downloads (Pure)

Comparison of empirical and predicted substrate temperature during surface melting of microalloyed steel using TIG technique and considering three shielding gases

Munoz De Escalona, P., Walker, A., Ogwu, A., Mridha, S. & Baker, T. N., 31 May 2019, In : Applied Surface Science. 477, p. 179-183 5 p.

Research output: Contribution to journalArticle

Open Access
File
Steel
Shielding
Melting
Gases
Substrates
Reactive sputtering
Stoichiometry
Magnetron sputtering
Chromium
Electric properties
19 Downloads (Pure)
Open Access
File
Ionic Liquids
Oxide films
Capacitance
Thin films
Electrodes

Silver thin film electrodes for supercapacitor application

Oje, A. I., Ogwu, A. A., Mirzaeian, M., Oje, A. M. & Tsendzughul, N., 15 Sep 2019, In : Applied Surface Science. 488, p. 142-150 9 p.

Research output: Contribution to journalArticle

electrochemical capacitors
Silver
silver
Thin films
Electrodes
37 Downloads (Pure)
Open Access
File
Aerogels
aerogels
electrochemical capacitors
activated carbon
electrode materials

Profiles

Aerogels
electrochemical capacitors
Carbon
electrode materials
Formaldehyde