Smart clothing – the future of wearable electronics

Technology for producing electricity from motion is already available for shoes. British company Pavegen have also produced tiles that produce electricity when walked on, which are used at Heathrow Airport to power wall-mounted light-emitting diode lights.

However, what if clothing could do the same? Smart clothes have been in development for decades and offer a wide range of functions, including heating, cooling and physiological monitoring. A major drawback to these clothes is that they require a constant power source, for which the only option is a standard battery. Such batteries are heavy to carry and have a limited energy storage capacity which must be recharged. The development of power-generating clothes could offer a solution by providing a continuous source of energy to smart clothes.

Electricity in clothes is mainly produced by body motion, body heat or the sun’s energy. Kinetic energy can be utilised by the piezoelectric effect, triboelectricity or electromagnetic induction. Certain materials become charged when rubbed over a different material (eg, rubbing a balloon on your head) which generates electricity called ‘triboelectricity’. Further, solar cells use the photovoltaic effect, through which electricity is generated when two different materials in close contact produce an electrical voltage when exposed to light; when these materials are connected in closed loop, electricity is produced.

Patent landscape
Smart clothing technology is still in development, with the majority of patents having been filed by universities. Key universities filing in this domain include:

• Zhongyuan University of Technology;
• Huazhong University of Science and Technology; and
• Sungkyunkwan University.

Earlier filings in this domain involved separate components attached to a garment – rather than integrated within it – for generating electricity, such as solar panels or piezoelectric materials. However, this had various disadvantages, including:

• increased weight;
• reduced comfort;
• restricted movement; and
• attachments which were:
  • inflexible;
  • non-washable; and
  • non-water resistant.

There has been a staggering rise in patent filings in recent years to resolve these issues (eg, converting the power-generating modules in fibres or yarns that can be weaved together to form a garment). Patents for materials which use triboelectricity and wind energy have also been disclosed.

Under development
Smart clothing technology is still under development and is years away from being commercially available. Key barriers to the commercialisation of this technology include the mass manufacturing of garments and the fact that the materials are not environment friendly – materials used in the manufacturing of solar cell fibres are volatile and therefore alternatives must be developed. This provides an opportunity for the key players in the wearable electronic industry, as the majority of patents in this technology are filed by universities and independent inventors. Therefore, collaboration or licensing may be the best way to establish a strong patent portfolio.

The smart clothing market is expected to grow by more than $4 billion by 2024 and power-generating clothes could be a big part of that market. Future applications may include the development of batteries in the form of fibres which could be integrated into power producing textiles. This is certainly a market to keep an eye on.