Imagine a future where a doctor is alerted to a change in a patient’s vital signs and calls them with a prognosis before they even realize they are ill. Or a consumer never worries about the possibility that a smartphone’s screen might be cracked when dropped? Or a diabetic with an internal monitor, powered by their stomach acid, that detects when they eat?
All of these scenarios may seem far from reality but, thanks to advances in stretchable and flexible electronics, they are becoming increasingly plausible.
“Recent advances in materials science and mechanical engineering have enabled the realization of high-performance electronic systems in soft, flexible and stretchable formats,” said materials scientist Canan Dagdeviren, director of the Conformable Decoders research group at the Massachusetts Institute of Technology (MIT) Media Lab in Cambridge, Massachusetts.
Like many of the IoT-enabled devices that have risen in popularity today, these new flexible and stretchable electronic solutions are very affordable and have the potential to be managed via smartphone apps. Businesses are taking note. In fact, according to a 2016 report by Grand View Research, the global flexible electronics market is estimated to be worth more than US$87 million (€75 million) by 2024.
According to a 2016 report by Grand View Research, the global flexible electronics market is estimated to be worth more than US$87 million (€75 million) by 2024.
Roel Vertegaal, director of the Human Media Laboratory at Canada’s Queens University, believes flexible and stretchable electronics will help shape the future of screens. His team is working on a range of innovations, including a flexible smartphone that is full-color, high-resolution and wireless; a flexible holographic smartphone capable of rendering 3D images without the need for head tracking or glasses; and a gaming remote with a cylindrical user interface.
“Flexible screens offer a variety of benefits,” Vertegaal said. “They are lighter and cheaper than conventional electronics and, from a usability point of view, they allow interactions in the third dimension by bending. What’s more, they are pretty unbreakable. A cracked screen could soon be a thing of the past.”
Human applications for flexible electronics are already taking shape.
“Stretchable and flexible electronics, while maintaining the same properties as conventional electronics, can be made into any curvilinear shape to be conformal with the human body,” said Yonggang Huang, professor of Mechanical Engineering and Civil Environmental Engineering at Northwestern University in Evanston, Illinois.
Huang worked with physical chemist and materials scientist John Rogers at the University of Illinois, along with Massachusetts-based wearables company MC10, to develop a stretchable electronic device for skincare giant L’Oréal at the company’s New Jersey technology incubator. The device, which is applied to the skin and paired with an app via near-field communication (NFC), contains photosensitive dyes that change color when exposed to UV rays. L’Oreal said that 60% of people who use the app experience less sunburn and 30% are using more sunscreen.
Meanwhile, MC10 partnered with Belgium-based biopharmaceutical company UCB to investigate how data-gathering sensors could be applied to the skin to monitor Parkinson’s disease. The focus was on “improving understanding about patient experiences, and evolving these insights to improve the management of neurological conditions – providing patients with better control and allowing them to improve treatment outcomes,” said Erik Janssen, UCB’s vice president of Global New Patient Solutions in Neurology.
THE PATH TO COMMERCIAL VIABILITY
Despite these successes, the true potential of flexible and stretchable electronics has yet to be realized. James Hayward, senior technology analyst at market research firm IDTEchEx, headquartered in Cambridge, UK, said that while some components of this type have passed the proof-of-concept stage, many more are not yet mature.
“Several types of stretchable and conformable electronics are commercially viable today, but they are generally in separate niches and need to be collated for growth and expansion to occur,” he said.
Takao Someya, a professor in the Department of Electrical and Electronic Engineering at the University of Tokyo, Japan, also sees a need for greater attention to achieving even more elasticity.
“Most of the stretchable innovations we see available today still have some sort of rigidity,” he said. “This is because they often require a rechargeable battery or wire of some description and, because of the multiple components, they are often encased in a rigid silicon casing. It’s a challenge to create a solution that is durable and soft at the same time.”
MIT’s Media Lab’s Dagdeviren agrees. “Today’s electronics are up to six orders of magnitude stiffer than soft tissue,” she said. “As a result, when we want to integrate electronics with biology, there are severe challenges related to mechanical and geometrical form mismatch.”
A PRINTED SOLUTION
Heng Pan, assistant professor of mechanical and aerospace engineering at the Missouri University of Science and Technology, believes the answer may lie in 3D printing.
“Additive manufacturing has the benefit that it can easily change from one material to the other and integrate all the different materials together in one print,” Pan said in a recent interview with R&D Magazine. “You can pretty much print any material in 3D geometry. We believe the additive technique has a very strong advantage in the creation of electronics.”
Raytheon Integrated Defense Systems in Tewksbury, Massachusetts, for example, has established the Raytheon-University of Massachusetts Lowell Research Institute (RURI) to accelerate the development of flexible printed electronics for the US Department of Defense. They hope to create bendable, stretchable devices that can be applied to medical devices, tents, backpacks, vehicles and wireless monitoring for buildings.
“Raytheon is engaging with partners across industry, government and academia to implement the use of materials and processes for printed radio frequency structures,” said Mary Herndon, senior principal engineer at Raytheon. “In platforms that are size or weight constrained, the ability to have flexible and conformal electronics is expected to yield better integration and lower profile assemblies.”
Brazilian company Sunew is using 3D-printing techniques to create a flexible solar panel solution that could be used in smart buildings, cities and vehicles. Sunew’s organic photovoltaic (OPV) technology has a high tolerance for vibration, so vehicles are considered an especially promising application environment.
“Now that we have semiconductors that are liquids, the production process is essentially printing,” Sunew CEO Tiago Alves said. “It’s a lower-temperature, continuous process at zero marginal cost. It takes a good amount of investment to reach the production level needed for a factory, but once that is achieved it is very efficient.”
Sunew’s OPVs compare favorably with traditional methods for producing photovoltaics. “Delivering efficiency approximately 20 times that of traditional technologies and a payback time of two months instead of two years, they are also 50 to 100 times lighter than conventional solar panels,” Alves said.
A FLEXIBLE FUTURE?
Flexible electronics also have implications for advances in ingestible, biodegradable semiconductors. Researchers at MIT, for example, have teamed up with Boston’s Brigham and Women’s Hospital (BWH) to develop flexible devices that can sense movement and ingestion in the stomach. The devices can reside in the stomach for at least two days, sense the ingestion of a meal and harvest energy from movement in the gastrointestinal tract. Moreover, they can harvest energy from movement in the gastrointestinal tract; such energy might be used to power novel ingestible electronic systems.
“Just as a wearable device like a FitBit can help track and quantify how many steps a person takes, we envision a device that could reside in the stomach and quantify how frequently a person is eating,” Carlo Traverso, a gastroenterologist and biomedical engineer at BWH, said. One possible application of this would be in monitoring patients with diabetes.
Experts at Boston’s Harvard Business School are working on a similar innovation.
“We anticipate significant development in the area of ingestible flexible electronics,” said Giovanni Traverso, an instructor of medicine at Harvard Medical School. “In the GI tract, flexible electronics could be applied for sensing movement and therefore could monitor and identify difficulties in the stomach of patients suffering from diabetes. Also, such systems could be applied for the monitoring of ingestion events.”
University of Tokyo’s Someya believes such applications are just the start of what flexible electronics might achieve in the years ahead.
“In the medium term, I see those with serious conditions using this type of sensor to monitor vital information such as heart rate, respiration rate, blood pressure, temperature and oxygenation levels,” Someya said. “But ultimately, it’s possible that we all have one of these devices. As a result, potential illnesses could be spotted before we’re even aware of them. This could transform the way we deliver health care across the globe.”