Clothes based on cling film could help keep us cool in hot climates, scientists say.

They have created a hi-tech textile version of the popular food wrap that acts as personal air conditioning system.

T-shirts, dresses and suits made from the cooling material should keep the body some 3°C cooler than conventional fabrics, which could cut air conditioning bills in half.

The researchers created a three-ply version of the material - two sheets of treated polyethylene separated by a cotton mesh for strength and thickness (pictured left). Pictured right is an electron-scanning microscope image of the material

WHY IS MAKING COOL CLOTH SO HARD? While humans have been wearing furs and cloths to keep warm for thousands of years, the development of 'cooler' clothing for hot summer days has remained challenging. This is because, at normal skin temperatures of 34°C, the human body emits mid-infrared radiation in the wavelength range that partially overlaps with that of the visible light spectrum. This means cloth that blocks visible light often traps in body heat. Advertisement

'If you can cool the person rather than the building where they work or live, that will save energy' said Yi Cui, an associate professor of materials science and engineering and of photon science at Stanford University in California.

The new material works by allowing the body to remove heat in two ways.

It lets perspiration evaporate through the material - something ordinary fabrics already do – but also provides a second, revolutionary cooling mechanism; allowing heat that the body emits as infrared radiation to pass through the plastic textile.

All objects, including our bodies, throw off heat in the form of infrared radiation, an invisible and benign wavelength of light that can be trapped by fabric, such as a blanket, to keep us warm.

Engineers have developed a low-cost, plastic-based material that if woven into clothing, could cool your body far more efficiently than natural or synthetic clothes can today (stock image)

This thermal radiation escaping from our bodies is what makes us visible in the dark through night-vision goggles.

Shanhui Fan, a professor of electrical engineering explained: '40 to 60 per cent of our body heat is dissipated as infrared radiation when we are sitting in an office.

'But until now there has been little or no research on designing the thermal radiation characteristics of textiles.'

To develop their cooling textile, the Stanford researchers started with polyethylene - the clear, clingy plastic we use as kitchen wrap – and altered it to have a number of characteristics desirable in material for cool clothes, allowing thermal radiation, air and water vapour to pass through, as well as making it opaque.

THE DEODORANT THAT PREVENTS BODY ODOUR Traditional formulas act by either masking smells, or blocking pores to prevent sweating at all. However, this new deodorant stops the chemicals in sweat from turning into bad smells in the first place. Sweat secretions themselves are odourless, and it is by the action of bacteria that they are transformed into volatile, smelly molecules. The deodorant contains molecularly imprinted polymers (MIPs), which are synthetic antibodies capable of specific moldcular recognition. The MIPs capture the precursors of smelly compounds, amidst a multitude of other molecules present in human sweat. Advertisement

The easiest attribute was allowing infrared radiation to pass through the material, because this is a characteristic of ordinary polyethylene food wrap.

The researchers then found a variety of polyethylene commonly used in battery making with a microscopic structure that appears opaque, but lets infrared radiation through, which could let body heat escape if made into clothing.

They modified the industrial polyethylene by treating it with benign chemicals to enable water vapour molecules to evaporate through microscopic pores in the plastic, enabling it to breathe like a natural fibre.

That success gave the researchers a single-sheet material that met their three basic criteria for a cooling fabric.

The material is transparent to human body infrared radiation, opaque to visible light, and permeable to perspiration vapour. Pictured is a microscopic view of its structure

But they needed to make it more fabric-like. To do this, they created a three-ply version - two sheets of treated polyethylene separated by a cotton mesh for strength and thickness.

To test the cooling potential of their three-ply construct compared to a cotton fabric of comparable thickness, they placed a small swatch of each material on a surface that was as warm as bare skin and measured how much heat each material trapped.

'Wearing anything traps some heat and makes the skin warmer,' Professor Fan said.

'If dissipating thermal radiation were our only concern, then it would be best to wear nothing.'

The comparison showed the cotton fabric made the skin surface 3.6°F warmer than their new cooling textile.

The researchers said this difference means that a person dressed in their new material might feel less inclined to turn on a fan or air conditioner.

The experts are now working on creating the fabric in different colours and textures as well as exploring how to make it feel more cloth-like.

Adapting a material already mass produced for the battery industry could make it easier to create products.