A cross-section of bamboo, a naturally-occurring porous substance
In our competitive world, we are always looking for more efficient, sustainable and intelligent engineering solutions. We are searching for growth while operating in a resource-depleted, energy-constrained world. The ultimate aim is doing more with less. Many natural resources are reaching their peak in terms of cost or quality. The availability of these raw materials, coupled with the governmental push towards a low carbon economy, puts pressure on the manufacturing industry.
In a bid to combat this, engineers are developing new ways to achieve resource efficiency at factory level. Innovative materials can provide high performance and multi-functionality. This means that finished products use less material and weigh less, without sacrificing performance. Another method involves using advanced manufacturing processes. These can convert metals, ceramics or plastics into finished products with fewer steps and less waste.
With this difficult task in mind, engineers go back to basics.
Nature is an important source of inspiration when it comes the design and manufacture of multifunctional materials. In nature, shape, form and functionality tend to be optimised. For example, bones, quills, plants stems, trees trunks and even sea shells contain porous structures, perfected by years of evolution. Learning from those systems allows us to design high performance structures such as a car chassis. These use less material but maintain the same mechanical performance. Lightweight cars mean less fuel consumption and lower emissions.
My team and I have devised a new manufacturing process to create these bio-inspired structures. Our method uses a beam of ultrasound directed onto a porous material while it is forming. By controlling the acoustics, mass within the material can be moved, added or erased. Less material is removed where a load is expected, leaving areas of higher density. Lower density zones appear where forces are not applied and stiffness is not required.
A great advantage of this technique is the ‘net-shape’ process. This gives digital control over the product’s properties and quality without extra manufacturing steps. The process produces almost zero waste, which is important when using expensive raw materials.
Using this ultrasound beam, we have produced materials with enhanced chemical and biodegradable properties that can mimic bone. We have even used this method to make medical implants which can host cells and enhance their growth. In this way, bone fractures and soft tissue wounds can heal quickly and more effectively. In the future, our research may enable the production of orthopaedic implants that can be easily customised to the patient. Innovative biotechnology like this helps alleviate the growing needs of an ageing society.
Image by Carmen Torres-Sánchez.