Integrated hetero-nanosensor array for environment monitoring

Low-power and ultra-compact nanosensors for air quality monitoring have been developed by using localized and selective synthesis of nanomaterials

Article  |  Fall 2015

Recently, air pollution problem has become a critical problem worldwide. According to World Health Organization (WHO), 7 million people suffered premature deaths due to air pollution in 2012. Although air pollution monitoring systems have been installed in a few public places in metropolitan cities, they are expensive, heavy, and complicated. On the other hand, people’s interests in their personal health and the environment are dramatically increasing. As a result, the needs for ultra-compact, low-cost, and low-power devices for air quality monitoring are high.

Nanomaterials and microelectronic devices can provide a solution to these needs. In particular, one-dimensional nanomaterials such as silicon nanowires, carbon nanotubes, and metal oxide nanowires can provide high sensitivity to harmful gases such as nitrogen dioxide (NO2), carbon monoxide (CO), and hydrogen sulfide (H2S) due to their small dimensions, high surface-to-volume ratio and high chemical reactivity. Furthermore, these advantages enable the implementation of low-power and ultra-compact sensors. However, the manipulation, assembly, and integration of one-dimensional nanomaterials on functional devices has been extremely complicated, time-consuming, and unreliable.

Prof. Inkyu Park in the Department of Mechanical Engineering, in collaboration with Dr. Zhiyong Li at Hewlett Packard Laboratory and Prof. Albert P. Pisano at the University of California at San Diego, developed a novel method to the selective synthesis and direct integration of one-dimensional nanomaterials on microelectronic devices. This method is based on the generation of local hotspots in the electronic circuit by Joule heating, which generates the convective mass transfer of precursor molecules towards hot spots and localized endothermal chemical reactions at the local hot spot. This approach allows the selective and direct integration of one-dimensional nanomaterials. Furthermore, an array of heterogeneous nanomaterials can be fabricated by combining with a parallel supply of precursor chemicals within a microfluidic channel. His group has used this heterogeneous nanomaterial array for multiplexed detection of several harmful gases such as NO2, CO, and H2S. They were able to realize low-power, ultra-compact, and high-performance gas sensors that can be used for personalized environmental monitoring.

This work was published in Advanced Materials (2015, 27, pp1207-1215) as a front cover article, ACS Applied Materials and Interfaces (2015, 7, pp. 10152-10161) and Scientific Reports (2015, 5, pp8149).