Combining cutting-edge technologies with the knowledge and skills of expert process engineers, the Melbourne Centre for Nanofabrication (MCN) has established a formidable track record in the field of micro and nanotechnology in just a few years of operation.

Debuting in March 2010 as the flagship facility of Australian National Fabrication Facility (ANFF)-Victoria, the MCN is a joint venture between six Victorian Universities and the CSIRO and is backed by $50m worth of investment in micro/nanotechnology infrastructure. Located in Clayton, in the heart of the South-East Melbourne Innovation Precinct, the Centre is openly accessible to both academic and industry clientele.

In the six years since its launch, the MCN has been involved in a growing array of projects and ground-breaking innovations in areas ranging from renewable energy sources to life-saving medical device breakthroughs. A look at some of the Centre’s more recent projects shows that the business of innovation is in no danger of slowing down.

Rapid prototyping to understand particle diffusion

A team of researchers from Melbourne University have applied laser-based microscopy techniques to understand the processes that control the diffusion of particles during advanced self-assembly and transport from examples like carbon nanotubes settling at an interface or the alignment of rod-like zinc oxide crystals during solar cell fabrication. Leading the project are MCN Technology Fellow Professor Ray Dagastine and PhD student Christopher Bolton, who are focused on a critical element of this work; the fabrication of specially designed optical prisms that are used to control light. The traditional approach is to use custom-designed and fabricated optical prisms made from high-quality optical glass that can only be sourced from international suppliers, making the design a slow, expensive process where the original intent is often lost in translation.

Using MCN’s advanced 3D printing capabilities, the team were able to rapidly fabricate complicated objects made from optically transparent materials. Through exploring various approaches to printing optical components, as well as experimenting with different materials and settings, they achieved optimum printing results that would not otherwise have been possible through a commercial print supplier. The team has also been refining techniques for polishing printed objects to a standard that permits their use with Class-3A/B lasers, greatly accelerating the development of a new microscopy technique currently under investigation.

Advanced rapid prototyping tools of this kind enable and accelerate research that might otherwise be considered impractical using traditional fabrication pathways. Reduced time and cost in fabricating complicated optical components opens the door for innovation which is free from conventional constraints and ultimately supports, in this case, lowered entry barriers to novel microscopy techniques in research and teaching environments as well as creating opportunities for future commercialisation.

High-performance microfluidics boost solar panel efficiency

The global drive towards making solar energy more competitive against low-cost fossil fuels has given rise to some amazing solar technologies. However, one of the biggest and least publicised challenges that all solar cell researchers face is the stability and scalability of their inventions outside of the laboratory environment. For example, for every 10-degree Celsius increase in operating temperature, most solar cells become around 5% less efficient in converting sunlight into electricity. Under the relentless Australian sun, this can typically mean a 10%-15% reduction in energy yield; a reality that largely negates the efficiency gains researchers have achieved over the last few decades.

Since 2013, the CSIRO Microfluidics team led by Dr Yonggang Zhu, a Technology Fellow at MCN, has been developing a novel thermal management system to address some of the fundamental challenges associated with solar photovoltaic (PV) technologies. The project is part of a $4m Science and Industry Endowment Fund (SIEF) project – ‘High performance solar cell technology with integrated nanoplasmonic thin film and thermal management systems’. Swinburne University of Technology and CSIRO researchers have worked jointly to overcome the efficiency losses that solar cells suffer when exposed to these high temperatures.

In tackling this problem, the CSIRO team has developed a novel heatpipe plate system that can potentially be integrated with conventional PV panels. The system utilises unique microscale thermal and fluid behaviours to remove heat with high efficiency. The devices were fabricated and tested in the Micro and Nanomanufacturing Laboratory, a satellite ANFF-Victoria facility based in CSIRO’s Clayton campus.

The heatpipe plate is fabricated from metallic materials, has a thickness of a few millimetres and can be mass-produced at low costs. While there is internal microflow within the plate, the integrated device has no moving parts and can potentially last for over 10-20 years making it ideal for coping with challenging environments and the integration with PV panels.

The technology developed from the project will generate benefits in the energy sector by recovering the electricity loss due to heating effects of up to 10%-15%. This will ultimately help to reduce greenhouse gas emissions. Future work will focus on the integration of the system with PV panels and mass production techniques.

Ultra-thin Plasmene – new scope for sensing devices and nano-electronics

Furthering development in the work of ultra-thin 2D materials that are electrically conductive, flexible and robust, MCN Technology Fellow Professor Wenlong Cheng and his team created Plasmene. Similar to Graphene in that it is a free-standing, one-particle-thick superlattice, Plasmene differs in that it is entirely artificial and produced via a bottom-up, self-assembly approach.

This approach utilises silver-coated gold nanospheres that are covered with polystyrene tethers suspended in a chloroform solution. This is then dropped onto a water droplet on a copper mesh, after which the chloroform evaporates leaving the nanospheres trapped in the grid, forming a tightly packed lattice-like sheet, nanometres thick but with macroscopic lateral dimensions.

Plasmene’s unique plasmonic (the physics of amplifying and/or concentrating electromagnetic energy) properties separate it from its graphite-based cousin. Its superior robustness and ability to be folded into geometrically well-defined origami shapes also distinguishes this novel material from other 2D materials. Professor Cheng’s group is experimenting with Plasmene for both sensing devices and nano-electronics. The nano-sheets can be used as a surface adhesive and applied directly to food, money or other common items to detect trace amounts of chemicals from pesticides and drugs that are otherwise difficult to detect.

A particularly interesting outcome of this work is the creation of incredible geometric origami shapes using the Focused Ion Beam (FIB) capability at MCN. ‘Gentle’ FIB milling is used to partially etch the Plasmene sheets by removing the surface-binding polysterene molecules using particular designs. These areas can then be folded by inducing local heating along the milled areas and the angles can be precisely controlled by programming the milling depth of the FIB. This gives Professor Cheng and his team versatile control over the size, shape and topological features of the origami created. Complex shapes such as cubes, hexagons, hearts and even the ‘flying bird’ effect have been achieved.

“This folding ability will be useful for future optoelectronics,” says Professor Cheng. “As Plasmene is cost-effective to make, this could see the development of a range of cheap, new, nanoscale electronic devices. We are also trying to understand how the origami effect can be useful for sensing applications as it is possible for it to affect the sensitivity of the sensors.”

“Micro-factories” for rapid development of high-value biochemicals

Internationally, the race is on to discover new enzymes and other biomolecules with valuable properties such as pharmaceuticals. Vast ‘libraries’ of candidate genes and enzyme variant combinations need to be produced, screened and selected against many different potential targets. Discovery might require millions, or even billions of reaction combinations to make a valuable strike.

Again, CSIRO is working with the MCN to create a new microchip technology to give Australian industry the tools necessary for success in this race. Just as electronic microchips revolutionised our economy, fluidic microchips are set to transform a whole range of industries from “tricorders” that put a pathology laboratory in a doctor’s hand, to micro-factories to screen the next generation of pharmaceuticals or industrial catalysts.

Led by Dr Yonggang Zhu, the CSIRO team is building fluidic microchips that create “micro-reactors” out of tiny droplets surrounded by special oils that contain and carry these tiny vessels to various unit operations on a microfluidic chip. These tiny droplets are a few microns across and contain only a few picolitres of fluid — such environments are advantageous as they mimic the physical and chemical conditions inside real biological environments.

They are created by sequentially merging water in oil droplets, inserting precisely measured (tiny) amounts of a specific chemical or biological reagent, mixing and incubating them with real-time control of the reaction time and conditions, performing in-situ analysis using a variety of micro-fabricated optical and electronic means and transporting selected droplets at high speed to final destinations based on the real-time analysis results. All of these features can be designed into a plastic microchip a just few centimetres long that can be mass produced in the MCN laboratories.

A new generation of power electronics

Power electronics underpin the future of effective and efficient generation and distribution of electrical power in the developed world as they are responsible for control circuits in green energy infrastructure and replacements for mechanical switches in on-pole distribution networks. Diamond is predicted to be the future material of choice for power electronic devices because of its high thermal conductivity, dielectric strength and mobility with various Figures of Merit ranking diamond as an order of magnitude better in these applications than its nearest competitor.

Researchers recently recorded the largest reported negative electron affinity (NEA) to date on diamond using magnesium adsorption on a previously oxygen-terminated surface. This large NEA and low work function results in a very high electron yield from the diamond surface, paving the way for better microelectronic devices that rely on extracting electrons, such as high-power vacuum diodes (used in power electronics).

Starting with a single crystal of diamond grown in MCN’s state-of-the-art diamond deposition suite, the research team created an atomically thin layer of magnesium atoms attached to the diamond with oxygen atoms. The magnesium layer lowered the energy required to extract electrons from the diamond while the oxygen atoms kept the structure robust. The team then measured the resulting structure at the Soft X-Ray Spectroscopy beamline at the Australian Synchrotron (adjacent to the MCN).

As well as resulting in a very high NEA, the process undertaken by the team was notable for its straightforward application and for producing a surface that can withstand exposure to air and water immersion without significant degradation. The simplicity of this process will allow this surface preparation to be easily incorporated into manufacturing diamond electronic devices with longer operational lifetimes.

Other practical applications of this work include highly sensitive light detectors such as those used for night vision goggles and the potential for using diamond as an electron emission source in liquids to help chemists control sophisticated chemical reactions more easily.