Final Report: Low-power, Small Form-factor Benzene Sensor for Mobile Devices-based Exposure Monitoring

EPA Contract Number: EPD14016
Title: Low-power, Small Form-factor Benzene Sensor for Mobile Devices-based Exposure Monitoring
Investigators: Debnath, Dr. Ratan
Small Business: N5 Sensors, Inc.
EPA Contact: Manager, SBIR Program
Phase: I
Project Period: May 1, 2014 through April 30, 2015
Project Amount: $99,191
RFA: Small Business Innovation Research (SBIR) - Phase I (2014) RFA Text |  Recipients Lists
Research Category: Air Quality and Air Toxics , SBIR - Air Pollution Monitoring and Control , Small Business Innovation Research (SBIR)

Description:

N5 Sensors’ (N5) EPA Phase I project established the feasibility of the chip-scale technology for detection of volatile organic compounds (VOCs) selectively using a low-power sensor platform. This technology utilizes the same processes used for mass-manufacturing of electronic integrated circuit (IC) chips, resulting in a low-power, hand-held, and low-cost solution for measuring these analytes. To the best of our knowledge, this is the first demonstration of a high-throughput production process for making chip-scale gas sensors using nanoengineered semiconducting material. The sensor manufacturing process is highly scalable and has very limited environmental impact, unlike other commercially available sensor technologies. EPA Phase I project allowed N5 Sensors to establish a state-of-the-art sensor quality-assurance program, which is essential for a sensor company to be successful.

Summary/Accomplishments (Outputs/Outcomes):

During Phase I, the focus of the work was on proving the feasibility of the technology, feasibility of the manufacturing process and reliability assesments. In the last 6 months, N5 developed and manufactured three generations of benzene, toluene, ethylbenzene and xylene (BETX) sensors, and with each generation, N5 demonstrated improved performance  compared to the previous one. In each generation, the response time and detection limit were greatly improved, with a current response time (T90) ~ 20s and a detection limit of ~ 1 ppm. This was accomplished mostly by changes in the semiconducter layer design, optimized sensor designs with implementation of follow-on innovative sensor designs and optimized manufacturing processes. The recovery time is still longer than desired (mins), but N5 is confident that it will be easily improved in the following gernerations as the nanocluster coverage and sizes are fully optimized. During Phase I, N5 developed a streamlined sensor design and manufactureing process, which allows us to develop new generation sensors much more rapidy.

Conclusions:

For the Phase I SBIR project, N5 Sensors, Inc., developed and demonstrated unique, highly-selective chip-scale BTEX sensors, utilizing nanoengineered gallium nitride (GaN) photoconductors functionalized with multicomponent nanoclusters of metal-oxides and metals. By combining the “designer” adsorption properties of multicomponent nanoclusters together with sensitive transduction capability of nanostructured GaN backbones, N5 Sensors demonstrated sensors for BTEX. Feasibility of the chip-scale microsensor technology was demonstrated by designing sensors, manufacturing them and testing their sensitivity to interferent chemicals with minimal cross-sensitivity to various components of environmental matrix, namely reactive gases, and non-target gases. Phase I results established the manufacturability of the process, robustness of the sensors and a clear pathway for further research and development of a product.

Using the results obtained in Phase I, N5 has been able to engage industry leaders (Honeywell, Industrial Scientific) in further evaluation of the technology for a specific hand-held benzene detection solution. During the project, N5 also engaged various community organizations (Global Community Monitors, Public Lab) to understand the need for low-cost benzene sensors (and sensors for other related environmental hazards) for end users (citizens). N5 has garnered significant interest from stakeholders, which justifies further development.

Supplemental Keywords:

benzene sensor, mobile device, exposure monitoring, air quality