Biomimicry to rethink interior thermoregulation and purification technologies

Our cars accompany us on our daily journeys. Every day, they enable millions of people to be mobile across the world: in cities, near coasts, in mountains, countryside, forests and even deserts.

Whatever the environment, the level of consumer demands has risen considerably over the last few decades. Whether it's snowing, raining, windy, in periods of heatwave or in periods of freezing cold, we expect from our vehicle the same degree of thermal comfort as that of our home.

In urban environments, users also expect their vehicle to guarantee good air quality in the passenger compartment, purified of emissions and particles present on the roads.

In this context, manufacturers and equipment manufacturers are playing the card of air conditioning, heating and filtration technologies. Complex, these devices consume energy and deserve to be improved. How can we optimise and develop the functionning of these technologies? What innovative solutions can we explore?

To ensure the physiological functions of species, nature has also been able to invent particularly effective and sober ventilation and thermoregulation techniques. The same goes for the management of light, an essential source of energy in ecosystems, which conditions the behaviour of many species.

This same need to ensure the physiological functions of species has led to the development of particularly sophisticated techniques for purifying air and surfaces (self-cleaning), particularly in the plant world.

These natural design methods can provide unparalleled sources of learning for the development of solutions to regulate cabin temperature and purify interior air.

Thanks to a detailed understanding of the functions and techniques present in species and thanks to a skillful extrapolation of biological "best practices", biomimicry opens the possibility of inspiring technologies that are more efficient, more durable and reliable and less energy-intensive.

Bioxegy offers you an overview of the remarkable properties of living things in this matter and also discusses a certain number of avenues of interest!

1 1 - Earwax: an optimised dust filter.

In the human ear and some mammals', a wax called cerumen lines the ear canal. This material acts as a very effective dust filter.

This structure is particularly interesting to study and opens many doors to technological innovations thanks to biomimicry.

At the Georgia Institute of Technology, mechanical engineering doctoral student Alexis Noel, a diving enthusiast, wondered about the properties of earwax, noting that it was capable of retaining water in the ears to the point of blocking them completely.

Helped by her teachers, A.Noel therefore studied the mechanical capabilities of wax. She discovered that earwax breaks up a web of wax between the hairs of the ear canal to capture dust.

Subjected to deformations caused by the movement of the jaw, the ear canal changes from an oval to round shape, thus acting mechanically on the earwax. Once saturated with dust, the wax dislodges from the ear and evacuates trapped dust. A new cycle then begins.

This discovery highlights a particularly simple and effective mechanism, and could thus have concrete applications in air filtration systems in homes and cars, by trapping and then evacuating volatile particles.

Crédits images : ©JACOPIN / BSIP / AFP

2 Polar bear hair: making sophisticated insulating textiles

Living things are capable of surviving and even thriving in sometimes extreme conditions. The polar bear, inhabiting Arctic regions, is a perfect example. It owes its resistance to polar cold to its fur and more precisely to the microstructure of its hair. These are fibers which are 200 micrometers in diameter. The interior is hollow, porous and insulating. The whole is held together by a rigid outer layer.

Researchers at Zhejiang University in China borrowed the trick to create a high-tech textile. They have designed an advanced manufacturing system, called "freeze spinning", which generates a fiber whose microstructure imitates that of polar bear hair. His heart is porous. This fiber is then woven and assembled to create a bio-inspired textile.

Particularly efficient, it has remarkable insulating and breathable properties . Complete with conductive carbon tubes, the textile can even heat up!

This same type of textile designed by biomimicry could equip vehicle interiors, in the form of coverings for internal walls or even materials for seats.

3 Green plants: depollution made by nature

Plants are capable of capturing low molecular mass volatile organic compounds (SO2, NOx, O3, CO, formaldehyde, benzene, toluene) through pores called stomata, located on the leaves, which constantly open and close. They act as real filters.

Some plants absorb and eliminate significant amounts of benzene, xylene, ammonia, formaldehyde or trichlorethylene. These are substances capable of causing problems such as irritation, dizziness, headaches, nausea, and which can be found in the environment of a vehicle.

Geranium, for example, is a herbaceous plant from the Geraniaceae family which is capable of depolluting the air by absorbing ammonia, benzene, formalin and xylene.

This filtration capacity is particularly interesting to study and opens many doors to biomimicry.

At the end of the 1980s, NASA joined forces with ALCA (Associated Landscape Contractors of America) to study its depolluting properties for green plants.

The objective of this study, called the NASA Clean Air Study, was to identify the green plants most effective in ridding the air of various toxic agents. Certain species were sent to the International Space Station to purify the air there.

These biological properties could inspire new mechanisms for purifying vehicle interiors.