Heat or Cool a Person with the Wristify Personal Air Conditioner

November 2, 2013, By Sanjeev Ramachandran

A group of students from MIT has come up with a successful prototype of what may be called a “personalized” air conditioner.

If the prototype makes it to the next stage, the result would be a significant answer to the energy crisis that experts believe looms in our future, due to the unbelievable rise in the demand and use of air conditioners.

Going by what folks at Wired say , in 2007, 87 percent of US households used air conditioning against 11 percent in Brazil and a mere 2 percent in India.


The facts get disturbing when you learn that experts say, by 2025, developing nations like Brazil and India will provide more than a billion new consumers for the air conditioner producing industry.

At present, the United States alone is accountable for 16.5 percent of energy use. Imagine the crisis that will soon hit us if developing countries, with more tropical climate, too start consuming energy in such a large scale.

This is exactly when the prototype, Wristify, becomes relevant. At a time when we are consuming way too much energy at homes and offices to make ourselves comfortable, a group of students has turned back and asked a simple question to themselves; why can’t we heat and cool our own bodies instead?

Voila! Wristify was made ! The prototype is a thermoelectric bracelet that will regulate the temperature of persons wearing it by exposing their skin to alternating pulses of hot and cold as needed.

It gained attention at MADMEC, a competition hosted by the school’s Material Science and Engineering Program. The prototype won a cash prize of $10,000, which the founders of the prototype said they would invest on further development.

Sam Shames, one among the founders of the product explains how the team came to think of developing a product like this – they were inspired by a simple day-to-day problem –keeping everyone happy in a room where no one can agree which temperature to set for the air conditioner.

Shames began researching on the issue, and he found his answer in a paper that appeared in a physiology journal, which explained how heating and cooling different parts of the body could result in how warm or cool, we feel.

“The human body and human skin is not like a thermometer. If I put something cold directly on your body at a constant temperature, the body acclimates and no longer perceives it as cold”, Shames has been quoted as saying.


This is something we can relate to, for example, when you jump into a lake, at first, it is chilling cold but after a while, your body gets used to it. Shames say that by continually introducing a sudden jolt of coolness your body could be tricked into feeling cold. And this is exactly what Wristify does.

In the process of building the prototype, the inventors – Sam Shames, Mike Gibson, a second-year Ph.D. student, David Cohen-Tanugi, a fourth-year Ph.D. student, and Matt Smith, a postdoctoral researcher, had to figure out how to exploit this perpetual trick best.

Their research conclusion was that anything with a temperature change greater than 0.1 degree Celsius would produce the effect they desired. Wristify uses thermoelectrics to both warm and cool a patch of skin.

This will change the temperature of that particular surface at a rate of 0.4 degrees Celsius per second.

According to the inventors, the product is still being refined to attain that right temperature. Thus, it will alternatively turn off and on for ten seconds and five seconds respectively.

After testing the product on their family and friends, Shames say, “The most common reaction you get is that you see someone smile.”He says people definitely thought this technology could work.

While their focus so far was to provide the technical proof for their theory, now they are determined to make it into a complete product. They say that none of the components are expensive, Shames also adds that they can produce the same effect with half of the skin space than what the prototype occupies, which will make it more compatible. Shames add that they are conscious that the look of the product is also of importance.

So yes, though this might not solve the AC energy problem at one go, it could certainly control our energy consumption. Wearable tech  has indeed come a long way.

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