Electronics have a 'nose' for gas detection

Researchers at the Holst Centre in Belguim and Imec in the Netherlands are using ink-jet printing techniques to create polymer-coated microbridges that can detect parts per million (ppm) concentration levels of chemicals in the air.

Currently, sensors such as these are made from quartz crystals or chemi-resistors but their low power efficiency makes them unsuitable for portable electronic systems. ‘Our objective in the end is to make energy autonomous systems that you could integrate into a mobile phone,’ said Sywert Brongersma, project leader.

The microbridges are embedded with piezoelectric ‘shakers’ in a high-density array, which cause them to vibrate individually when they come into contact with chemicals in the air. Changes in their modes of vibration are a sign of changes in vapour absorption in their coatings and an indicator of the presence of the targeted chemical.

The researchers claim that the high length-to-thickness ratio of the microbridges means that the gas sensor chip has a high sensitivity to low-concentration vapours. Integration of piezoelectric read-out schemes also makes it low in power consumption (less than 1mW per bridge).