Led by Professor Chen Xiaodong of the School of Materials Science & Engineering at Nanyang Technological University (NTU), the team created a customisable supercapacitor where the structure and shape can be changed after it is manufactured, while retaining its function as a power source. Existing stretchable supercapacitors are made into predetermined designs and structures, but this design can be stretched in multiple directions so that it is less likely to be mismatched when joined to other components.
The supercapacitor has a honeycomb-like structure built from a strengthened manganese dioxide nanowire composite that stores four times more charge than most existing stretchable supercapacitors. When stretched to four times its original length it also maintains nearly 97 per cent of the charge, even after 10,000 stretching cycles. While manganese dioxide is a common material for supercapacitors, the long nanowire structure, strengthened with a network of carbon nanotubes and nanocellulose fibres, allows the electrodes to withstand the strains of the customisation process.
Pairing the supercapacitor with a sensor and placed on the human elbow, it performed better than existing stretchable supercapacitors, producing a stable stream of signals even when the arm was swinging, says Chen. The data was then transmitted wirelessly to external devices, such as one that captures a patient’s heart rate.
The team believes the supercapacitor could be easily mass-produced as it would rely on existing manufacturing technologies at SGD$0.13 (USD$0.10) to produce 1 cm2 of the material and has filed a patent for the technology.
“A reliable and editable supercapacitor is important for development of the wearable electronics industry. It also opens up all sorts of possibilities in the realm of the ‘Internet-of-Things’ when wearable electronics can reliably power themselves and connect and communicate with appliances in the home and other environments,” said Chen. “My own dream is to one day combine our flexible supercapacitors with wearable sensors for health and sports performance diagnostics. With the ability for wearable electronics to power themselves, you could imagine the day when we create a device that could be used to monitor a marathon runner during a race with great sensitivity, detecting signals from both under and over-exertion.”
The NTU team also worked with Dr. Loh Xian Jun, Senior Scientist and Head of the Soft Materials Department at the Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR). “Customisable and versatile, these interconnected, fabric-like power sources are able to offer a plug-and-play functionality while maintaining good performance. Being highly stretchable, these flexible power sources are promising next-generation ‘fabric’ energy storage devices that could be integrated into wearable electronics,” he said.
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