Holography has stimulated some of the world’s most intriguing and profound theoretical and experimental work in materials science and engineering optics. Holographic displays are used for applications in data storage, light trapping, security, sensing and optical devices. Currently available fabrication techniques for holography remain expertise-dependent, costly and time consuming, limiting the widespread personalised use of holograms. In our research group, we tackle this limitation by investigating the development of efficient and low-cost techniques for the rapid fabrication of holograms, required for practical applications. We conduct fundamental research into the chemistry and physics of materials and engineer their tuneable photonic structures and bulk properties to ultimately improve their performance in rationally designed security, biosensing, data storage and optical devices. We have developed a range of smart polymer based holographic sensors for use in healthcare and industry. The principle of operation of such sensors is simple – a laser is used to imprint an hologram within the polymer, and changes in the polymer swelling, refractive index or other properties causes a change in the image of the hologram – either colour, image shape or position. This can be accurately measured using either spectrophotometer or a digital camera, or in some cases (where the shift in reflected wavelength is sufficiently large), by eye. In practice, this means we have a unique, simple optical platform for measuring multiple analytes.
We have constructed holographic sensors for pH, glucose, lactate, alcohol, oil in water, water in oil, ions (potassium, sodium, calcium etc.), nerve agents, organic vapours (VOCs) and a broad range of other liquid and gaseous analytes. Unique technology developed here allows us to make holograms in almost any clear or translucent polymer film, utilising a very broad range of metallic nanoparticles as the basis of diffraction. At present we are developing more holographic sensors in collaboration with industrial partners for use in both healthcare and manufacturing. Particular attention has been devoted to developing highly selective real time sensors for glucose for monitoring bacterial growth, spore germination and glucose concentrations in tear fluid via holographic contact lenses and based on phenylboronate receptors. Current research relates to the development of holographic “virtual” instruments, holographic optical elements, a number of new fabrication methodologies based on laser ablation and specific sensors for monitoring glucose, VOC’s, gases, pregnancy, nitric oxide and microorganisms.
Examples of the smart hologram technology: (a) pH sensitive holograms, (b) breath-sensitive visual holograms, (c) brand protection/authentication, (d) the reel-to-reel production technology, and (e) high resolution moisture-sensitive hologram.
List of Projects and Members:
Holographgic Sensors for Aeropspace Applications – Dr Colin Davidson
Nitric Oxide Sensor – Miss Jennifer Versnel
Immunoassay for Pregnancy –
Holographic Sensors for Urinalysis – and Dr Fernando da Cruz Vasconcellos