Smart clothing computes wearer's thermal needs

March 09, 2016 // By Julien Happich
According to Pekka Tuomaala, Principal Scientist at the VTT Technical Research Centre of Finland, smart clothing of the future will automatically adjust their temperature according to the wearer's actual needs.

In November last year, the Finnish research center had unveiled one of the potential building blocks for such self-tuning thermally active clothes: microscopic channel networks hot embossed onto large areas of soft and elastic plastic film, through which cold or hot liquid could be pumped.
Integrated into smart clothing, the microfluidic channels are analogous to the cardiovascular system which irrigates different parts of the body (though it is the human metabolism which defines the blood's distribution at a given time).

Microfluidic channels to be integrated into smart clothing, with a thermoregulator backpack.

Prior research established that humans dissipate approximately 85% of their body's heat loss through the skin, so the smart irrigated fabric would act as not only a comfort layer but also double up as a thermoregulatory skin.

But before such "personalised air conditioning" smart fabrics can maintain the wearer's thermal comfort, they need to be able to regulate their temperature appropriately, so as to automatically adjust to external conditions.

This calls for accurate human thermal model calculations, and the research lab has just developed the tools for that, enabling to correlate surrounding temperature and on-body temperature measurement with a person's thermal sensations.

As described in Riikka Holopainen's PhD dissertation, "A human thermal model for improved thermal comfort", the newly developed model takes into account the effect of human thermoregulation and individual human parameters on thermal sensation and comfort, to calculate more realistically the interaction and non-uniform transient heat transfer between the skin surface and the surrounding air and building structures.