San Francisco, May 19 (IANS): A team of US engineers has developed a wearable patch that could provide personalized cooling and heating at home, work or on the go.

The soft, stretchy patch cools or warms a user's skin to a comfortable temperature and keeps it there as the ambient temperature changes, said researchers from the University of California-San Diego.

It is powered by a flexible, stretchable battery pack and can be embedded in clothing and wearing it could help save energy on air conditioning and heating.

"This type of device can improve your personal thermal comfort whether you are commuting on a hot day or feeling too cold in your office," said Renkun Chen, professor of mechanical and aerospace engineering who led the study.

The device, which is at the proof-of-concept stage, could also save energy.

"If wearing this device can make you feel comfortable within a wider temperature range, you won't need to turn down the thermostat as much in the summer or crank up the heat as much in the winter," Chen said in a paper published in the journal Science Advances..

Chen and his team designed the device to be comfortable and convenient to wear.

The patch is made of thermo-electric alloys -- materials that use electricity to create a temperature difference and vice versa -- sandwiched between stretchy elastomer sheets.

The device physically cools or heats the skin to a temperature that the wearer chooses.

"You could place this on spots that tend to warm up or cool down faster than the rest of the body, such as the back, neck, feet or arms, in order to stay comfortable when it gets too hot or cold," said study's first author Sahngki Hong.

The ultimate goal is to combine multiple patches together to create smart clothing that can be worn for personalized cooling and heating.

The team is now working on patches that could be built into a prototype cooling and heating vest.

"We've solved the fundamental problems, now we're tackling the big engineering issues -- the electronics, hardware and developing a mobile app to control the temperature," Chen said.