- The benefits of plastic
- Stretchable plastic enables flexible electronics and robotics
- Smart, self-sterilising plastic film kills viruses using UV light
- Electronic skin can help create robots with human-like sensitivity
- Eco-friendly plastic can instantly self-heal when damaged
- Closing thoughts
While there is no doubt that the emissions generated to produce plastic and the problems surrounding their disposal are literally insurmountable, we can all agree that plastics have certainly provided countless benefits in terms of convenience, versatility, durability, and hygiene. And recent developments have shown that they can be of even more value when combined with electronic systems like synaptic transistors, biological processes, and robotics, leading to exciting new frontiers in plastics.
The benefits of plastic
Around 1600 BC, the ancient Mesoamericans first processed natural rubber into various items and figurines. Then we started experimenting with waxes, natural resins, and polymers. In the 19th century, modern thermoplastics were developed, and with each passing decade our reliance on this material has grown. Currently, hundreds of types of plastic and rubber materials are commercially available and are used in a myriad of ways, day in and day out, in everything we do.
In 2021, the global plastic market was valued at $593.00 billion, and between 2022 and 2030 it is expected to expand at a compound annual growth rate (CAGR) of 3.7 per cent.
Grand View Research
Almost every aspect of our daily lives involves plastic. Think shoes, bags, and clothing, and also the household appliances we use, the cars we drive, the electronic devices we depend on at work, food packaging, surgical equipment… the list is endless. Plastics also provide mobility and autonomy for people with disabilities – and let’s not forget that plastic has made the modern-day microchip possible. Can you imagine a world without it? In comparison to competing materials, plastic is very resource-efficient and has a significant strength-to-weight ratio. It has high ductility, toughness, bio-inertness, corrosion resistance, excellent thermal and electrical insulation, and outstanding durability at a relatively low lifetime cost. Technological progress like we’ve experienced in the past century would not have been possible without the invention of plastics. Here are some numbers: according to Grand View Research, the global plastic market was valued at $593.00 billion in 2021, and between 2022 and 2030, it is expected to expand at a compound annual growth rate (CAGR) of 3.7 per cent.
Some incredible recent innovations in, and novel applications of, plastic include highly stretchable and flexible foundations for soft robotics, self-sterilising plastic film that kills a myriad of viruses, electronic skin that can ‘feel’ pressure and even pain, and eco-friendly plastic that can instantly self-heal when damaged.
Stretchable plastic enables flexible electronics and robotics
Using ‘controlled crystallisation’, researchers at the University of Texas at Austin have created a type of plastic – inspired by living organisms – that is soft and stretchy in some areas, yet hard and rigid in others. Using only light and a catalyst that changes molecular properties like elasticity and hardness, the researchers managed to create a plastic-like material that is 10 times tougher than natural rubber and – unlike other mixed materials – doesn’t break or tear when stretched. The researchers started out with a small molecule that binds with other, similar molecules to form polymers resembling those used in common types of plastic. They then added a catalyst that, when exposed to blue LEDs, resulted in the formation of more rigid material in the exposed parts of the polymer, while the unexposed parts remained soft and stretchy.
Zachariah Page, assistant professor of chemistry and corresponding author on the research paper, says: “This is the first material of its type. The ability to control crystallisation, and therefore the physical properties of the material, with the application of light is potentially transformative for wearable electronics or actuators in soft robotics”. The material could be used in robotics to improve durability and movement, and as a flexible foundation for electronics in wearable technology or medical devices.
Smart, self-sterilising plastic film kills viruses using UV light
A team of scientists at Queen’s University Belfast have developed a self-sterilising plastic film that can stop viruses in their tracks and prevent them from spreading in hospitals and care homes. The film contains titanium dioxide nanoparticles that react with UV light – even light released by fluorescent light bulbs – to release reactive oxygen molecules that neutralise viruses by the millions, including ones that linger on surfaces and clothes and are hard to kill. The low-cost and easily scalable self-sterilising material was tested on two types of influenza, a picornavirus and SARS2. Scientists say the film could be made into protective gear like hospital aprons, as well as curtains, tablecloths, and plastic packaging materials for the food-processing sector.
Professor Andrew Mills from the university’s chemistry department says: “This is the first time that anything like this has been developed. This film could replace many of the disposable plastic films used in the healthcare industry as it has the added value of being self-sterilising at no real extra cost”. He continues: “Through rigorous testing we have found that it is effective at killing viruses with just room light – this is the first time that anything like this has been developed and we hope that it will be a huge benefit to society”.
“In the future, this research could be the basis for a more advanced electronic skin which enables robots capable of exploring and interacting with the world in new ways, or building prosthetic limbs which are capable of near-human levels of touch sensitivity.”
Fengyuan Liu, researcher at the University of Glasgow
Electronic skin can help create robots with human-like sensitivity
In Scotland, a team of engineers from the University of Glasgow have developed electronic skin (e-skin) that contains a new kind of processing system based on synaptic transistors, which enables the skin to mimic neural pathways in the brain and learn to recognise and respond to external stimuli, such as pressure. This breakthrough could help develop a new type of intelligent robot with human-like skin sensitivity that can be ‘taught to feel pain’.
To create electronic skin capable of a synapse-like response, the researchers printed a grid of 168 synaptic transistors made from zinc-oxide nanowires onto a flexible plastic surface. Connecting the synaptic transistor grid to touch receptors in the palm of a robotic hand enabled the sensors to register a change in their electrical resistance – causing the hand to ‘feel’ an object. Gentle touches created a different change in resistance than firmer touches, teaching the hand different levels of ‘touch’ sensitivity and mimicking the way our human sensory neurons work. The team even managed to make a robotic hand covered with the artificial skin ‘recoil’ as a result of a sharp jab in the middle of the palm.
Fengyuan Liu, a co-author of the research paper, said: “In the future, this research could be the basis for a more advanced electronic skin which enables robots capable of exploring and interacting with the world in new ways, or building prosthetic limbs which are capable of near-human levels of touch sensitivity”. The prostheses of the future might be capable of reacting to temperature sensations with human-like sensitivity and even be capable of ‘feeling pain’ – or learn from pressure sensations and be trained to respond appropriately.
According to Professor Ravinder Dahiya, leader of the team of researchers, the technology is based on the way humans learn early on how to respond to unexpected sensations in order to prevent future pain. He said: “What we’ve been able to create through this process is an electronic skin capable of distributed learning at the hardware level, which doesn’t need to send messages back and forth to a central processor before taking action. Instead, it greatly accelerates the process of responding to touch by cutting down the amount of computation required. We believe that this is a real step forward in our work towards creating large-scale neuromorphic printed electronic skin capable of responding appropriately to stimuli”.
Eco-friendly plastic can instantly self-heal when damaged
By making use of a technique called liquid-liquid phase separation (LLPS), a group headed by senior researcher Jianwei Li at Finland’s University of Turku has recently developed a supramolecular plastic with the mechanical strength of conventional plastic. Li explains: “Emerging evidence has shown that LLPS could be a significant process during the formation of cell compartments. Now, we advanced this bio- and physical-inspired phenomenon to tackle the grand challenge for our environment. I believe that more interesting materials will be explored with the LLPS process in the near future”.
The supramolecular plastics contain high-strength, non-covalent, and reversible bonds, giving them many useful properties and enabling a myriad of applications. They can become adhesive and instantly self-heal when damaged or broken. Think smartphone cases that fix themselves or car paint that automatically self-repairs scratches. The plastic is degradable or can easily be recycled after use. Study author Dr Jingjing Yu says: “Comparable with conventional plastics, our new supramolecular plastics are smarter as they not only retain the strong mechanical property but also reserve dynamic and reversible properties that make the material self-healable and reusable”.
Closing thoughts
For centuries, plastics have provided many benefits in terms of versatility, convenience, and durability. When combined with biological processes, robotics, and electronic systems, they can be of even more value, helping to shape the future of the plastics industry and driving it towards numerous high-tech and increasingly environmentally friendly applications. It’s also important to note that plastics and plastics-based smart materials are critical to ensuring that every industry in the world can continue to innovate, evolve, address complex challenges, and craft new solutions for a myriad of problems.
