Sensors Use On-Chip Integrated Read-Out Techniques for Gas Detection

Holst Center and Imec have created extremely sensitive integrated sensing components for detecting gases. The sensors are polymer-coated microbridges components placed in high-density arrays for detecting vapors having ppm-level concentrations by utilizing on-chip integrated read-out methods. This technology is useful for developing miniaturized electronic nose gadgets by virtue of its small form factor and less than 1 µW/bridge low power consumption features.

Wireless sensor nodes that have the ability to detect gaseous compounds chemically,  are attracting interest from markets like safety, food monitoring, and healthcare. One of the important gas sensing techniques adopted in uncontrolled environments relates to identifying the smells of vapors using multiple sensing receptors, known as an e-nose or electronic nose.

An accurate e-nose needs integrated, low power, small detectors that have separately tuned chemical coatings. Existing solutions, such as quartz crystals or chemi-resistors are not power-efficient or scalable for developing small form factor electronic noses.

Holst Centre and Imec have created state-of-the-art microbridges having embedded separate piezoelectric ‘shakers’ positioned inside a high-density array that has high fabrication yield. The new design permits speedy coating of many absorbents on separate microbridges by utilizing the commercial inkjet printing technology. Transformations in the modes of the individual vibrations of the suspended structures are tracked as clues of absorption of vapor in their coatings. By virtue of the microbridges’ large high length-to-thickness ratio, the new gas sensor chip of the Holst Centre and imec has a large sensitivity to vapors having low-concentration. Furthermore, by the implementation of integrated piezoelectric read-out designs, it was possibly to demonstrate low power operation.

Presently work is in progress for integrating the low-power based analog read-out circuits and structures for demonstrating simultaneous measurements from multiple structures. Such low-power based miniaturized e-nose technology implementation is useful for existing applications like cheese and wine monitoring, and in the future could be used for smelling human conditions like kidney and lung cancer diseases.