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Nanophotonic-Enabled Non-Dispersive Infrared Sensor Development

Primary Investigators:
Josh Caldwell
 
Brief Description of Project:
Nondispersive infrared (NDIR) gas sensing is a common and straightforward technique of monitoring the presence and concentration of ambient gases, such as CO and CO2. In its simplest geometry, an NDIR gas sensor consists of a broadband infrared (IR) emitter and an infrared detector that are separated at opposite ends of an opened highly-reflective chamber by a spectral bandpass filter. Light from the emitter is directed towards the detector and filtered in order to isolate the spectral region corresponding to the IR absorption of the gas molecules of interest. The intensity of the transmitted light through both the filter and gas is then measured by the detector. When trace amounts of the gas enter the chamber, a drop in intensity is read by the detector due to the absorption. In our lab we study methods for confining and manipulating light at the nanoscale, using what are called polaritons to achieve this goal. These polaritons can be used to realize a strongly absorbing optical antennas that when heated result in a narrowband and polarized infrared source using thermal emission. The narrow bandwidth can be implemented to eliminate the need for the bandpass filter, therefore providing a cheaper device with higher sensitivity to the gas molecule of interest. 

This project will focus on the design of a frequency-tunable, narrow linewidth absorption/emission infrared source, called a Nanophotonic InfraRed Emitting Metamaterial (NIREM) and its incorporation into a NDIR gas sensor. The goal will be to design a narrow linewidth and resonant frequency to match that of the molecule of interest. This offers a promising route towards achieving highly-sensitive NDIR sensors, significantly advancing the state of the art, while also potentially decreasing the energy consumption of the device.

Desired Qualifications:
Experience with electrical or mechanical structure design, fabrication and/or machine-shop experience.  Basic knowledge of infrared and optical experiments a plus.
 
Nature of Supervision:
Work in a hands-on environment. Weekly meetings with PI at a minimum, will be paired with 4th year graduate student for entirety of the Summer.
 
A Brief Research Plan (period is for 10 weeks):
With the guidance of graduate students and a postdoctoral fellow within the Caldwell lab, the summer student will design and demonstrate a proof-of-concept NIREM-based NDIR gas sensor. From this project the student will gain valuable experience in a wide variety of research skills such as using Matlab and electromagnetic modelling, performing Fourier transform infrared (FTIR) spectroscopy and other spectroscopic characterization techniques, and experience in the designing and fabrication of an optical device. The first step in this process would be for the student to determine the NIREM material and structural parameters necessary for exhibiting polaritonic absorption/emission at the frequency of the IR absorption of a non-hazardous gas, such as N2O. This would involve the use of in-house computational tools. The student will then participate in the nanoscale lithographic processing and/or assist in the growth of materials as needed to achieve the preliminary design. The student will then assist in designing a purged optical setup, where the concentration of the non-hazardous trace gas can be controllably introduced. The student will utilize an angle resolved thermal emission rig that is currently being constructed in our lab along with a state of the art infrared spectroscopy methods. Finally, the student will be assisted in performing thermal emission measurements using the purged optical system and tracking the IR absorption as a function of gas concentration, thus demonstrating the proof-of-concept for a polaritonic NDIR sensor.
 
Number of Open Slots: 1
 
Contact Information:
Name: Josh Caldwell
Department: Mechanical Engineering
Email: josh.caldwell@vanderbilt.edu