Although PM10 particles with a diameter of 10 μ m or smaller can also be inhaled into the lungs, PM2.5, as a representative, poses a more serious threat to human health. In order to detect these harmful pollutants and integrate them into wearable or mobile devices so that users can know and describe local air quality, Austrian scientists have developed the world’s smallest particle sensor. The harm of PM 2.5 lies in its ability to penetrate the lung blood barrier. If exposed to high pollution environment for a long time, it will lead to serious cardiovascular / respiratory diseases and other health problems. < / P > < p > in recent years, many cities have set up a large number of sites to monitor the concentration of PM 2.5 particles in the surrounding areas, and the U.S. Environmental Protection Agency is also using the national monitoring network to track air quality. < / P > < p > however, the research team at TU Graz, Austria, has been working hard to create a more cost-effective, compact and versatile solution that can alert individual users in real time under specific conditions. < / P > < p > by working with scientists from semiconductor manufacturers AMS Ag and silicon Australia labs, the team has reduced the instruments used in conventional air quality monitoring equipment to the smallest size to date. < / P > < p > as shown in the above figure, the size of the new sensor is only 12 × 9 × 3 mm (0.47 × 0.35 × 0.11 inch), smaller than two euro cent coins, and can be easily integrated into mobile devices such as smart phones, smart watches, or fitness bracelets. Paul maierhofer, who led the study, < / P > < p > said the results were close to the limits of physics and technology. To achieve this goal, many unique techniques are involved. < / P > < p > “the technology can also help users speak up for good habits, such as avoiding high pollution routes when jogging or commuting. In addition, thanks to the substantial cost reduction, the sensor can also fill the market gap and find wider application scenarios indoors and outdoors. “. Didi Qingju bicycle has entered 150 cities