Microrefrigeration... could this be used in flashlights?
One set of candidates are known as paraelectric materials. These act like batteries when they undergo a temperature change: attach electrodes to them and they generate a current. This effect is used in infra-red cameras. An array of tiny pieces of paraelectric material can sense the heat radiated by, for example, a person, and the pattern of the array's electrical outputs can then be used to construct an image. But until recently no one had bothered much with the inverse of this process. That inverse exists, however. Apply an appropriate current to a paraelectric material and it will cool down.
http://www.economist.com/science/displaystory.cfm?story_id=8407182
One set of candidates are known as paraelectric materials. These act like batteries when they undergo a temperature change: attach electrodes to them and they generate a current. This effect is used in infra-red cameras. An array of tiny pieces of paraelectric material can sense the heat radiated by, for example, a person, and the pattern of the array's electrical outputs can then be used to construct an image. But until recently no one had bothered much with the inverse of this process. That inverse exists, however. Apply an appropriate current to a paraelectric material and it will cool down.
http://www.economist.com/science/displaystory.cfm?story_id=8407182