A number of interesting inventions by university students from Jilin province struck people's eyes at a scientific invention exhibition at the University of Jilin in the province's capital Changchun city, on May 16.

Many of the inventions at the exhibit are quite practical. One highlight of the event, which was part of the province's Science and Technology Week, was the "no ink" printing technology developed by Jilin University's chemistry dept, which according to one estimate, could save 300 billion yuan ($48 billion) for China's printing industry annually. And it costs only about 1 percent of the current inkjet printing approach.

"No-ink"　printing machine, at student invention exhibition in Changchun, on May 16, [Photo by Sun Jianyi/provided to China Daily]

The new invention uses a special dye that can change color when it comes in contact with water, allowing the ordinary printing method to be replaced by a method that allows paper to be reused. Traditional printing technology has a problem with paper and ink usage, resulting in a waste of resources and money. So, Zhang Xiao'an, the inventor and a teacher in the chemistry dept, and his team spent several years researching the no-ink approach in a variety of colors. The characters or letters printed on the paper can be retained for different lengths of time, with the maximum being 100 hours, and allowing for each piece of paper to be used at least 15 times. And it is compatible with current ink jet print technology, so "customers only need to buy water printing paper and a water-ink box," according to Sheng Lan, a member of the team.

Sheng did add that the new technology cannot replace ink printing totally because it cannot be stored for long periods of time and is only useful for documents that will be read only one time, for example in confidential meetings by companies or government. Still it has good market prospects and the inventors are applying for a patent.

Other standouts at the exhibit:

A color-changing paint protection film for cars, developed by a team of young entrepreneurs at Jilin University, which attracted a large crowd of car owners. This film is not added to the car's window, but sprayed on and can change color in different light conditions, improving the safety of night driving. It is also much easier to repair than conventional film.

Special trash bin

Multipurpose trash bin [Photo by Sun Jianyi/provided to China Daily]

Garbage sorting is a serious matter in many countries but the traditional method is to put several bins together with separate labels, which wastes space. This unified trash bin developed by Jilin University's biological and agricultural engineering dept combines different garbage types in one bin, with different sections according to the physical and biological features of the garbage and the amount. It is expected to improve the efficiency of city sanitation workers and the researchers say that once their invention goes into mass production, they will donate their profit from it to sanitation workers' salaries.

Page-turning machine [Photo by Sun Jianyi/provided to China Daily]

Other inventions included a wireless electrocardiogram that can help family members monitor the health of an elderly relative even from a distance, and some things for lazybones, such as a machine that can turn book pages for you, and an auto-cleaning vehicle.