Grantee Research Project Results
Final Report: Photonic Crystal Slot Waveguide Spectrometer for Monitoring of Volatile Organic Compounds in Groundwater and Hazardous Pollutants in Air
EPA Contract Number: EPD10047Title: Photonic Crystal Slot Waveguide Spectrometer for Monitoring of Volatile Organic Compounds in Groundwater and Hazardous Pollutants in Air
Investigators: Chakravarty, Swapnajit
Small Business: Omega Optics, Inc.
EPA Contact: Richards, April
Phase: I
Project Period: March 1, 2010 through August 31, 2010
Project Amount: $70,000
RFA: Small Business Innovation Research (SBIR) - Phase I (2010) RFA Text | Recipients Lists
Research Category: Small Business Innovation Research (SBIR) , SBIR - Nanotechnology
Description:
Summary/Accomplishments (Outputs/Outcomes):
Conclusions:
The lower exposure limit of methane is 5%. Omega Optics has successfully demonstrated experimentally methane detection below the lower exposure limit with a 300 µm-long photonic crystal slot waveguide on-chip platform, with near-infrared optical absorption signatures of methane at 1.665 µm. To Omega Optics' knowledge, the demonstrated photonic crystal slot waveguide on-chip optical absorption spectrometer is the smallest spectrometer for infrared optical absorption spectroscopy of gases. The detection limit is ~28 ppb for methane. The table below summarizes the essential requirements from a gas sensor and shows that Omega Optics' photonic crystal slot waveguide absorption spectrometer easily meets the requirements. No other technology currently can meet these requirements in terms of size, weight, sensitivity, price, and thus cost of ownership (COO).
The sensitivity of our device to the detection of toluene in water in the near infrared is 0.8 mg/L, which is lower than near infrared detection limits observed with PDMS disks in water (7 mg/L) in 10 mm long samples. Of course, with salinity enhanced water (0.12 mg/L) has been demonstrated in 5 mm long samples. The use of salinity enhancement, however, increases the processing steps for data collection. The device is more than an order of magnitude smaller in length than PDMS disks above. The experimentally demonstrated sensitivity of our device is smaller than 0.9 mg/L demonstrated with 11 meter long optical fibers. The limit of detection in the near infrared is believed to be approximately an order of magnitude smaller. Because the same device principle is applicable in the mid- and far infrared, detection sensitivities of few hundred ppt (v/v) are possible in the device. Also, response time in the device is a few seconds compared to ~60 minutes due to small thickness of the extraction phase for toluene to diffuse.
Supplemental Keywords:
small business, SBIR, EPA, greenhouse gas, hazardous air pollutants, HAP, volatile organic compounds, VOC, hazardous materials, pollutants, miniature spectrometer, monitoring, water monitoring, air monitoring, waveguide spectrometer, groundwater, chemical spectroscopy, absorption spectroscopy instrument, nanotechnology, lab-on-a-chip sensor, silicon lab-on-chip photonic crystal integrated infrared spectrometerThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.