Inside La Trobe University’s advanced materials lab, engineers are testing a new kind of concrete that will slash the construction industry’s carbon emissions. Nearby, their colleagues are taking inspiration from shark skin and insect wings to create new antibacterial surfaces. And in Tasmania’s forests, an adventurous robot is exploring the conditions inside wombat burrows.
Meet the La Trobe minds behind these exciting engineering endeavours and find out how their work will better our world.
1. Shark skin-inspired antibacterial surfaces
What do shark skin, cicada wings and rose petals have in common? According to Dr Avinash Baji, Senior Lecturer in Manufacturing Engineering in La Trobe’s Department of Engineering, they all have surface microstructures worth mimicking.
The tiny hierarchical structures on these surfaces contain natural antibacterial and antifouling properties, which prevent bacteria and organisms growing or attaching to them. Through a process called surface engineering, Avinash is imitating these microstructures to create new synthetic antimicrobial materials.
One of the main properties Avinash is investigating is wettability – that is, liquid’s attraction to a solid surface.
‘In our preliminary study, we copied hierarchical structures found on the surface of rose petals and translated them onto thin polymer films. We showed that the presence of these structures influences the wettability behaviour of the films. Next, we’ll demonstrate that the presence of these structures on polymer films also produces antibacterial properties,’ Avinash explains.
Through his research, Avinash hopes to create a material with superior antimicrobial abilities. The applications, he says, are vast.
For instance, the material could prevent bacterial and fungal cross-contamination in agriculture and food industries – such as on the equipment and tools used to process food crops, or on benches and utensils in commercial kitchens. It could also be used to stop the spread of disease in hospitals, on everything from fittings to face masks.
‘Nature-inspired antibacterial and antifouling materials can be used on high-contact surfaces like bedframes, door handles and tray-tables in hospitals and healthcare settings. The materials ensure these surfaces remain bacteria-free, which helps inhibit the spread of microbial infections,’ Avinash says.
‘Similarly, face masks using these antibacterial and antifouling materials could stop pathogenic microbes from attaching to them. They’re like another barrier of protection.’
A flow-on benefit of Avinash’s synthetic antimicrobial surfaces is their role in reducing our reliance on antibiotics.
‘Currently, tackling bacteria and biofilms typically relies on the use of antibiotics. However, each time we use antibiotics, we unwittingly encourage antibiotic resistance. Over time, drug-resistant strains of infectious diseases evolve,’ he says.
Instead of treating bacterial infections with antibiotics, then, new synthetic materials can stop bacteria from gripping surfaces in the first place. Suffice to say, the human health impacts of Avinash’s work go far beyond surface-level.
2. Low-carbon concrete for infrastructure
Concrete is a ubiquitous material. You’ll find it sculpted in Rome’s ancient Pantheon, or stalwart in China’s Three Gorges Dam. For millennia, it’s been used to build bridges, runways, high-rise buildings, drains, sewers and more.
But concrete’s versatility in construction comes at an enormous environmental cost. The carbon emissions from concrete – and specifically, by the cement binder it contains – make up 8 per cent of the world’s anthropogenic carbon dioxide (CO2).
That’s where engineers like Dr Vipul Patel come in. Vipul is a Senior Lecturer in Civil Engineering at La Trobe’s Bendigo campus. He’s developing low-carbon concrete using waste products from industry. The result is a new kind of concrete that does away with cement altogether.
‘As an effective binder in concrete, cement can be replaced by fly ash and slag. Fly ash and slag are waste products from the thermal power plant and steel industries, respectively. At La Trobe, we’re designing and testing a mixture using fly ash and slag from a local Victorian supplier, and the results are promising,’ says Vipul.
With an estimated 30 billion metric tons of concrete used globally each year, swapping out cement can help slash the construction industry’s carbon footprint. Already, low-carbon concrete is being used in some footpaths, driveways and low-rise structures. Vipul hopes his work will prove its safety and uncover even more applications.
‘Currently, Australian standards don’t provide specifications for low-carbon concrete use. So, I’m investigating the material properties of low-carbon concrete. I’m testing slabs and beams made of low-carbon concrete to compare their behaviour with that of traditional concrete,’ he says.
From checking strength and shrinkage, to assessing durability and impact resistance, Vipul’s testing will improve civil engineers’ understanding of the possibilities for using low-carbon concrete in construction. With atmospheric concentrations of carbon dioxide exceeding 412 parts per million in 2020, Vipul’s research couldn’t come sooner.
‘Climate change has become an urgent issue in the last decade and governments are embarking on programs to reduce carbon emissions. Low-carbon concrete technology can produce up to 64 per cent less greenhouse gas emissions when compared to cement-based concrete,’ he says.
By solving a global need for sustainable materials – and using industry by-products in the process – Vipul’s low-carbon concrete sounds like just the kind of building block the world needs.
3. Robots for native animal burrows
Meet the WomBot – a robot specially designed to navigate the disorienting maze of a wombat burrow. Designed by La Trobe alumnus and robotics engineer Associate Professor Dr Robert Ross during Melbourne’s pandemic lockdowns, the remote-controlled WomBot can explore spaces that were previously inaccessible.
‘Wombat burrows are narrow, muddy, and can be dozens of metres long and contain steep sections and sharp turns,’ Robert says.
‘WomBot allows us to enter and explore burrows without destroying them or using expensive ground-penetrating radar.’
So far, the WomBot has travelled inside 30 wombat burrows in the Tasmanian bush. Fitted with cameras, it shows scientists what’s inside a burrow, while managing burrow inclines of up to 22 degrees on its continuous tread tracks. The data it collects will help scientists better manage disease dynamics and improve wombat health.
For instance, by assessing the environmental conditions inside burrows, the WomBot has confirmed that they’re able to harbour parasitic scabies mites. Its environmental sensors measure the burrow’s temperature and humidity, while its gripper ‘paw’ can place and retrieve additional environmental sensors inside the burrow.
‘We found that the wombat burrows on average sat at around 11 degrees and had humidity levels of around 85 per cent. We estimate that female scabies mites could survive for between 16 and 18 days in these conditions – meaning infected wombats could be leaving mites behind for the next wombat to catch,’ Robert says.
Scabies mite infestations can be devastating for wombats. The mites cause sarcoptic mange – burying under a wombat’s skin, they trigger crusty lesions, extreme itchiness and hair loss. A severe mange outbreak contributed to a 94 per cent decline in common wombat population in Tasmania’s Narawntapu National Park. The disease is also affecting mainland Australia’s wombat populations.
Looking ahead, Robert hopes to harness the power of virtual reality to give more people an experience of life inside a wombat burrow.
'At the moment, we're integrating thermal cameras and a 360-degree camera to allow anyone to explore wombat burrows with a VR headset,' he says.
By harnessing the power of robotics to protect biodiversity and improve animal health, Robert’s work is just one example of how science and engineering can combine to help solve the major challenges of our time.
Images: Shark by Gerald Schömbs on Unsplash; La Trobe's Dr Avinash Baji at work in the laboratory; La Trobe's Dr Vipul Patel with concrete inside La Trobe's advanced materials and testing laboratory; Dr Vipul Patel in Bendigo's engineering building; the WomBot robot beside a toy wombat; La Trobe's Dr Robert Ross.