There have been some exciting developments in the field of material science recently. Innovative new materials such as carbon nanotubes and flexible substrates could improve the world around us. But what exactly are they and how can they be used?
Carbon nanotubes
Carbon nanotubes are essentially tubes made from graphene which have a revolutionary potential in several key industries.
What makes them special? Dr Theodore explains: ‘They are highly stable, they're incredibly strong and lightweight and they have some amazing electrical, thermal and mechanical properties.’ As a result of this, they have a lot of potential in the development of many interesting future materials and flexible sensors.
One of their key properties is they can behave both like a metal and be completely electrically conducting, or they can display the properties of a semiconductor where necessary. As a composite material, having carbon nanotubes as a conductor or semiconductor can allow materials like plastic to attain selective conductivity without affecting their durability or flexibility.
The tensile strength of carbon nanotubes varies but it can easily be at least 400 plus times that of steel, whilst having only around 1/6 of the density. NASA is looking at this as a potential material to use for ‘space elevators’ connecting earth to low orbit.
Like graphite, they are also extremely chemically stable and highly resistant to chemical impacts like weather, high temperatures, or oxygen corrosion.
There is also a lot of research going into their application in tissue engineering, particularly as a scaffolding to allow for bone growth, which has enormous potential for application in healthcare.
Flexible substrates
In material sciences, flexible substrates are loosely defined as a material on which a process is conducted. When it comes to sensing technology, the material itself is considered as the basis of an architecture and a flexible sensor has the substrate as a core component of the sensory function.
These substrates can take several forms, including ultra-thin glass, metal foil and polymer films (PDMS in particular).
In aerodynamics, the ability to have flexible sensors is a game-changer. Aerodynamic forces are complicated and notoriously difficult to compute. With current technology, such as computational fluid dynamics (CFD), even a small Formula 1 team can spend upwards of £10m for a six-month project using computer simulation - and even then, the real world cannot be simulated accurately with the number of possible variables.
All the current technologies for testing aerodynamics have significant drawbacks. The industry is crying out for truly flexible sensors that are thin and light enough, with enough density of sensors, that can be stretched over, say, the front plate of an F1 car, or the wing of an aircraft.
Flexible sensors that can produce real world data, in near real time conditions, is something that just haven’t been possible… until now.
In screens, the use of flexible substrates will significantly reduce the weight of flat panel displays and provide the ability to conform, bend, or roll a display into any shape.
Glass has typically been used for screens due to being a transparent barrier, but it is extremely brittle. Flexible OLED, based on a flexible substrate can be plastic, metal or ‘flexible glass’; however, the first generation of devices (from 2019) aren’t really ‘flexible’ from a user perspective - they include TVs or mobile phones with curved screens. Attempts to create devices with truly flexible or bendable screens have encountered issues (such as the Samsung Galaxy Fold) but as the second and third generation of such products rolls around, we should see exciting developments.
Remote health monitoring
Dr Theodore notes that a key consequence of the COVID-19 pandemic is that it demonstrates the ‘urgent need of both corporate organisations and healthcare institutions to adapt very quickly to the physical and mental health needs of its workforce.’
The rapidly aging population (globally) means there is a growing need to be able to monitor people’s health without the need for them to visit their GP.
In addition to this, the increase in remote working and general effects of the pandemic on the population means that people are going to be living increasingly fragmented lives and may be more anxious or aware of their overall health.
How can people be monitored remotely?
Hard sensors in general, such as ‘portable’ blood pressure monitors, are limited in practice to specific functions (and may still be rather bulky or cumbersome). They are not practical to be worn on the body or woven into garments.
By contrast, wearable soft sensors expand the range of functionality and reduce the rate of false positives, as data from numerous sensors (multiple data points) can be combined for a more holistic view of someone’s health.
Potential applications include sensors being woven into garments to monitor breathing. In emergency calls, when people are asked to report on their own breathing, the breathing itself can be disrupted. If this technology were inbuilt to a worn garment, this data would be more accurately available.
Posture is another often-overlooked aspect of health where wearable sensors could be very useful. The human body is not built to be sat for hours, hunched over at a desk - we are potentially sleepwalking into a health nightmare. Wearable sensors to monitor or alert us to our posture could be invaluable in preventing health problems in this area.
Overall, the ability to proactively alert and monitor in near real-time conditions (with wireless delivery and remote monitoring capabilities) when individuals start to exhibit symptoms is a critical component of our early-warning system for general, pandemic and age-related illness.
