Creating devices that are better for the environment may involve working up a good sweat. That's because engineers are using sweat to make systems that store energy. One such device is a type of capacitor. It is powered by sweat and can be used to charge a device. Researchers at the University of Glasgow in Scotland developed the device. A capacitor is an electrical component that stores energy physically, in a form very much like static electricity. (In contrast, batteries store energy chemically.)

The system recently developed is a supercapacitor. This is a capacitor with two conducting surfaces on which a charge of energy is stored. The energy it stores can be used later. The energy could power an LED light or a type of electronic. Researchers described their new model May 11, 2020 in a scientific journal. The findings are exciting because devices powered by sweat could pave the way to wearable tech that is both safer and better for the environment. Today's wearable electronics include gadgets strapped to the body, such as watches and fitness trackers. However, engineers are also creating electronics that are part of clothing or stuck onto the skin.

Batteries power most wearable devices today. Yet those batteries often contain chemicals that can harm the environment. That's where the idea of using a bodily fluid comes into play. Electrolytes(电解质) are minerals in your body that have an electric charge. With the device, the sweat serves as the electrolyte. "That's kind of a new way of using sweat, "observes Mallika Bariya. She is a scientist at the University of California, Berkeley. She did not take part in the new study. She says electrolytes are an important part of these supercapacitors. They're needed for these devices to provide power. Sweat is interesting, not gross, she argues. It can tell you about someone's health. Also, the chemical makeup of sweat can change depending on what part of the body makes it.

Xi'an, as the longest-running capital in ancient China, has shaped the country's culture and history. With a history of over 3, 000 years, it has given birth to many dynasties. If planning a short tour, be sure to visit the recommended attractions that truly capture the spirit of this ancient city. 

The Terracotta Army

The Terracotta Army is a remarkable archaeological find and a popular tourist destinationin China. Constructed by Emperor Qinshihuang in the 3rd century BC, it features life-size terracotta soldiers, horses, and chariots arranged in battle formation. The museum houses three vaults (墓穴) and an exhibition hall, with Vault One being the largest, displaying over 6, 000 figures. These sculptures offer insights of high value into ancient China's history, military, and culture. 

Ancient City Wall

Xi'an City Wall was built in the 14th century by Zhu Yuanzhang, the first Emperor of the Ming dynasty (1368-1644) as a military defense system. Now it is one of the oldest and best-preserved Chinese city walls. The wall is now a landmark, dividing the city into inner and outer areas. When you take a stroll or cycle on the massive wall, you can enjoy a good view of the city, the moat (护城河) and the watchtowers. 

Giant WildGoose Pagoda

The Giant Wild Goose Pagoda in China was built during the Tang Dynasty as a study place for Buddhist texts. It stored sutras (佛经) and sculptures brought from India by monk Xuan Zang, who translated scriptures here for 19 years. Situated in Da Ci'en Temple, the pagoda's impressive brick structure reflects traditional Chinese architecture, creating a solemn and magnificent atmosphere. 

Shaanxi History Museum

The Shaanxi History Museum displays 370, 000 relics found in Shaanxi, China, including bronze wares (青铜器) , pottery figures, gold and silverwares, and Tang Dynasty murals. 18 pieces are national treasures. Xi'an, the former capital, has many historical sites. The museum is divided into three sections, exhibiting artifacts from primitive eras to the late Qing Dynasty. 

After a day's labor, Andreas Fichtner and his colleagues have spliced (绞接) together three segments of fibers, creating a 12.5-kilometer-long fiber-optic (光学的) cable. It will stay buried in the snow to spy on the activity of Grfmsvotn, a dangerous, glacier-covered volcano.

Fichtner, a geophysicist at the Swiss Federal Institute of Technology, in Zurich, is one of the researchers using fiber optics to take the pulse of our planet. Much of their work is done in remote places, from the tops of volcanoes to the bottoms of seas, where traditional monitoring is too costly or difficult.

The technique used by Fichtner's team is called distributed acoustic sensing, or DAS. "It's almost like radar in the fiber," says the physicist Giuseppe Marra of the United Kingdom's National Physical Laboratory, in Teddington. While radar uses reflected radio waves to locate objects, DAS uses reflected light to detect events as varied as earthquake activity and moving traffic, and to determine where they occurred. Inside the cables are optical fibers. DAS involves shooting quick pulses of laser light down the fiber and detecting bits of light that scatter back to the laser source due to disturbances in the environment. When the earth's surface vibrates and shifts, it pulls the cables, so a detector can identify these small changes.

The New York Times points out that although wireless and satellite technology are booming, good old-fashioned cables are still the most efficient way to send information across oceans. Repurposing cables could give scientists the ability to monitor high-risk zones that were previously hard to reach. They could help detect earthquakes and tsunamis a few seconds earlier than traditional warning systems.

In addition, fiber-optic cables could also help solve some of the biggest challenges for humans. In the recent years, scientists have started to use them to measure ocean waves and access fault (断层) information. It is believed that fiber-optic cables will serve to benefit us greatly in the future.