The ‘Wristify’ prototype: Cool the individual, not the building

Over the centuries, subtle observations have triggered revolutionary innovations. Goethe’s play Faust spurred Nikola Tesla to invent the induction motor in 1888. The shape of the ancient ‘ouroboros’ symbol led chemist August Kekulé to raise the curtain on the chemical structure of benzene. In a similar vein, MIT senior Sam Shames tapped into the potential of ‘perceived temperature’.

Kekulé connected ouroboros and the structure of benzene

Shames observed that while in the same room, he felt hot while his mother felt cold. Logically, this seems paradoxical because the room is at a single temperature, not two! After reading a paper on physiology, however, Shames learnt that “locally heating and cooling different parts of the body has all sorts of effects on how hot or cold we think we are”. This simple observation inspired Shames to design a piece of tech that could bring about a paradigm shift in thermal comfort.

Before I introduce Shames’ prototype, a little note of context. A significant proportion of today’s energy goes into air conditioning (AC). In the US, AC “accounts for a full 16.5 percent of energy use”. Even more daunting is the fact that population growth in the future will no doubt increase the demand for cooling. How do we satisfy this future demand in a sustainable manner? Enter ‘Wristify’, an innovative device that could reduce the use of ACs around the world.

Wristify: a thermoelectric wristband that cools your body

Wristify is a wristband that cools (or heats) the body depending on conditions. It is based on the Peltier effect (a subset of the thermoelectric effect). Simply put, a lithium polymer battery supplies power to a copper-alloy heat sink. The heat sink dissipates heat, which in turn cools the skin. Wristify also includes an automated control system and a thermometer that work in tandem to maintain the right amount of cooling. Instead of continuously cooling the body, Wristify provides “sudden jolt[s] of cold”. Shames likens this process to jumping into a cold lake. “At first, it’s bracingly cold, but after a while, you get used to it”, he explains. These jolts are given in 10-second intervals to “trick the body into feeling cold”.

Schematic diagram of a Peltier heating/cooling element

The positives of the Wristify are numerous. Let’s begin with the positives that are design-related. Firstly, the final version of the Wristify should not be too expensive to manufacture. Three parts are required: a Peltier heating/cooling element, a heat sink and a battery. None of these parts are costly. Also, Shames claims that effective cooling can be achieved even with half the surface area, reducing cost. Secondly, no circulating fluids are involved in cooling, unlike ACs. This eliminates the possibility of any hazardous effects caused by fluids reacting with skin.

There are also sustainability-related positives of the Wristify. A substantial amount of energy is saved by cooling the individual and not the space. The team behind the prototype states that if ACs do not alter the temperature of a building by 1 degree Celsius, approximately “100 kilowatt-hours” can be saved per month. If implemented on a large scale, this technology can dramatically reduce energy consumption through ACs. Finally, the Wristify could increase the living standards of people living in hot developing countries.

Air conditioning takes up a significant proportion of the world’s energy

To gain a balanced picture of this product, it is also important to consider its drawbacks. The lithium polymer battery allows the Wristify to function for a limited lifetime of 8 hours. After this time period, batteries will need to be replaced. There is a psychological aspect that needs to be considered too. If the Wristify is in charge of regulating ‘perceived’ body temperature, what is the role of the natural cooling system of the body: perspiration? It is crucial that the design team makes sure the technology does not interfere in any way with the body’s natural processes.

Still metal and wires: The Wristify is in prototype stage

The Wristify is still in prototype stage. Should it go into production, it could reduce the world’s dependence on ACs for cooling. But one thing is clear to me: watches in the future will do much more than just tell the time!

References used:

http://www.wired.com/design/2013/10/an-ingenious-wristband-that-keeps-your-body-at-the-perfect-temperature-no-ac-required/

http://web.mit.edu/newsoffice/2013/madmec-design-competition-1017.html

http://www.extremetech.com/extreme/169951-wristify-a-personal-peltier-wrist-cooler-that-could-save-the-us-millions-in-energy-costs

http://www.dailymail.co.uk/sciencetech/article-2484022/Is-end-sky-high-energy-bills-Thermoelectric-wristband-body-warm-created-scientists.html