Energy harvesters enabling micro-power generation provide new levels of efficiency and automation in the built environment, process control, vehicles and healthcare. However, recently a large effort is being placed into developing the technology for integration into textiles. While on the surface this may seem niche, if we delve deeper we find there is a substantial opportunity for the technology here. Textiles are the most common human interface because 70% of surfaces touched each day are textiles, including clothes, bedding, wall covering, upholstery and flooring. Textiles are flexible, comfortable and consumer oriented. They are stretchable and conformable and they present large surface areas to work with. They are highly engineered and ordered structures produced by an established, efficient, global supply chain and a mass volume application platform.

Textile electronics is primarily used for sensing as in health monitoring, warming as in outdoor wear, display and lighting including illuminating t-shirts and party fashions and control as with sleeve controls for your iPod and woven rollable keyboards. Then there is logistics, notably RFID. That includes active RFID where there is a battery in the tag for real time location, mesh networking and so on. These batteries will have energy harvesting in future. Beyond clothing, the technology is being integrated into car and train seats. For example, EnOcean energy harvesters are used to monitor occupancy of seats in trains so that operators can judge when to add or remove carriages. The sensors are powered by the act of someone sitting on the seat.

Energy Harvesting and Sportswear

Adidas is moving forward with products such as the virtual trainer. Their subsidiary Textronics focuses exclusively on textile electronics, specifically Wearable Physiological Monitoring Systems. Here the vision is to easily measure body data to help the consumer manage health and wellness goals.

At Europe's largest event on Energy Harvesting & Storage (Munich, Germany June 21-22 http://www.IDTechEx.com/EHEurope), Decathlon (owned by Oxylane Group) will present on the opportunity for energy harvesting for electronics sports products. The presentation will cover energy requirements and user needs and requirements for energy harvesting products.

The Textile Becomes the Energy Harvester

Increasingly researchers are turning their attention to incorporating the energy harvesting elements into the textile itself. In the UK the University of Bolton has developed a novel technology that integrates piezoelectric polymer substrate and photovoltaic coating system to create a film or fibre structure that is capable of harvesting energy from nature, including sun, rain, wind, wave and tide.

The raw materials used are inexpensive starting with the piezoelectric material which is extruded and poled. Since the organic photovoltaic material system is made in a normal atmospheric environment, the cost associated with the whole structure is magnitudes less expensive than ceramic based photovoltaic. The resultant material system is flexible and can be incorporated in textiles for a wide variety of applications. The University will also be presenting at this event.

Researchers at the University of Southampton's School of Electronics and Computer Science (ECS) are developing technology that may enable people to power electronics through their clothes and the carpets they walk on. Dr Steve Beeby and his team aim to generate energy through people's movement, eliminating the need to change batteries on devices. In a project funded by the Engineering and Physical Sciences Research Council (EPSRC), the Southampton team will use rapid printing processes and active printed inks to create an energy harvesting film in textiles. This film can also be printed on carpets, enabling individuals to generate energy as they walk around the home or office.

In the US, Georgia Tech researchers led by materials-science Professor Zhong Lin Wang have made a flexible fiber coated with zinc oxide nanowires that can convert mechanical energy into electricity. The researchers say the fibers should be able to harvest any kind of vibration or motion for electric current. Gold-plated zinc oxide nanowires, each about 3.5 micrometers tall, are grown on a flexible polymer fiber and these nanowires brush against untreated nanowires, which flex and generate current. Yarn spun from the fibers could lead to fabrics that convert body movements into electric current.

Cetemmsa is another company overseeing research projects in the use of sensors in sportswear and accessories. The company hopes to develop a range of electronics that can be integrated into clothing which could appeal to athletes, including heart rate monitors, cooling technology and low-power lighting solutions. The company is also working on integrated power sources for added electronic functionality such as organic photovoltaics, as part of the EU-funded Dephotex project. Dephotex is a European collaborative research project, co-funded by the European Commission and will be carrying out research on Photovoltaic Textiles based on novel Fibres for 3 years from November 2008 to October 2011. Cetemmsa will be presenting on this at the IDTechEx Energy Harvesting & Storage event.

Solarprint, G24i and Konarka will also present on Photovoltaics, including covering new form factors of PV applicable to textiles. The IDTechEx "Energy Harvesting & Storage" event brings the whole topic together, exploring new leading edge work in sectors such as textiles. Register early to obtain the discount at http://www.IDTechEx.com/EHEurope.