Sensors and other electronics are usually made of rigid and stiff material such as metals and plastics. They cannot be stretched, twisted or thrown, and should be handled with care. But that is about to change. Researchers from the Institute of Textiles and Clothing at PolyU have developed a new technology that allows electronics to drape around our body comfortably. Defying our imagination, the researchers have engineered a new fabric that can conduct electricity, paving the way for stretchable electronics.
The pressure sensitive fabric is made of flexible polymers and nano-carbon materials. Through advanced fabrication process, conductive nano-carbon materials were laced onto polymer to create a thin layer that can transfer electricity. When stretched or pressed, the thickness of this layer changes, which leads to a change in the electric current and the resistance. The fabric will react to a pull or compression with an increase in resistance so that strain and pressure can be measured.
To transform this novel idea into reality, Prof. Xiaoming Tao and her team have to overcome a challenge: a loss of conductivity under a high degree of deformation. Employing novel textile engineering techniques, they have developed a highly conductive polymer that can withstand significant stretching. This material is also highly sensitive and reliable for touch sensing. Principal investigator Prof. Tao explained, "Our new fabric can be stretched like a rubber band and has high sensitivity to strain. We've also made another one that can withstand and respond to very high pressure up to 2000kPa. They are water-proof, washable and excellent in resistance to fatigue."
In the future, pressure sensors can be bent and stretched. More importantly, the flexible material is soft, light and breathable, and therefore is well tolerated by human skins. As it will work better and longer on human body, it opens up new possibilities for health care and medical applications such as wearable health monitoring devices. For example, a stretchy fabric sensor can measure intensive body movements and then send information wirelessly to a computer. Such electronics can adapt to any bent and moving body parts for health monitoring or remote control.
This novel technology has been applied and presented as a pair of smart shoes for round-the-clock health watch without a single wire or electrode on a person. Fellow researcher Dr Aaron Wang illustrated, "The pressure-sensitive fabric is made into a touch sensor in the shape of a sole. When fitted into the shoes, the sensor can detect when an elderly person falls over and then send alerts or track down a missing person with dementia when he is out and about." The research team is anticipating a future where medical devices can integrate seamlessly into the human body to track a patient's vital signs and transmit the signals to his/her doctor.
Dr Wang suggested more innovative possibilities in entertainment business, "Our stretchable sensors will be useful in fabric push buttons, game controllers and dance pads. Computer games will be more fun and edgy than ever."
"Our ultimate goal is to develop a deformable system integrated with computer power, wireless technologies and environmental power sources, which I believe will have a profound impact on telemedicine, health care delivery and sports training," said Prof. Tao.
This breakthrough was licensed to a start-up called AdvanPro Limited for further development and production. The University is keen in putting laboratory science into good use and in fact this company was set up by the researchers with the support from the Micro-fund program organized by the University's Institute for Entrepreneurship . In pursuit of knowledge transfer and entrepreneurship, the Institute is dedicated to give professional services and coordination support to help the aspiring entrepreneurs transform PolyU's innovations into applications which can make the world a better place.
Source and top image: Hong Kong Polytechnic University
For more read Stretchable Electronics Comes to Market