Gas flow

Researchers at Purdue University have shown how to create a new class of tiny sensors for applications ranging from environmental protection to pharmaceutical preservation.

Although similar "gas-flow sensors" are currently being used for a variety of industries, the new sensor is the first that works on the scale of micrometres and nanometres respectively, said Steven Wereley, an associate professor of mechanical engineering.

Gas-flow sensors currently used, including those in residential gas meters to determine how much to charge customers, operate on a principle known for at least 100 years. According to that principle, as gas flows over a surface, such as the wall of a pipe or an object flying through the air, molecules of gas nearest the surface remain stationary. The molecules farther away from the surface move progressively faster.

‘That model works really well in many situations, including aerodynamics and applications where the scale of the flow is large compared to the size of the molecules,’ Wereley said.