A gas sensor could one day be used to detect chemical weapon vapors or indicators of disease more precisely than current models do. The device also consumes less power, which is crucial for stretching battery life in a mineshaft or an isolated clinic.

A pump and compressor collect gas from the first tube and then send it into the second tube at regular intervals. The second tube is typically coated with polar polymers, which are positively charged at one end and negatively charged at the other. This coating slows down polar gas molecules, allowing the non-polar molecules to pass through more quickly. With this second clue, the researchers can identify the chemicals in the gas.

Source 

Also: Learn about an ultra-miniature image sensor.