1. Developing Environmental Trace Gas Sensors based on Quartz- Enhanced Photoacoustic Spectroscopy (QEPAS) Stacey Huang October 3, 2014 SOL Colloquim

2.  Objectives: develop laser technology for sensors and material processing  Current research projects: security applications (detection of improvised explosives, landmines), chip-based sensors, temperature sensors for process control, broad energy research  Work with industry partners to produce quality sensors TU Clausthal Laser Application Center Goslar, Germany Image credit: http://www.lac.tu- clausthal.de/fileadmin/_temp_/lac.jpghttp://www.lac.tu- clausthal.de/fileadmin/_temp_/lac.jpg

3.  To assist in building sensors and instrumentation for practical use in trace gas sensing  To gain a broader understanding of different approaches of laser-based sensors  To gain insight into the development and troubleshooting process of sensors industrial  Skills: experience with lab software, installation of sensor components (LEDs, tuning forks), handling of optics (alignment, laser characterization, handling lenses, etc.) Summer Internship Goals

4.  Tuning fork placed in target gas  Laser focused through tuning fork  Laser is modulated; i.e., intensity that the gas observes is changing  Gas heats and cools at the modulation frequency, producing pressure changes  Quartz tuning fork picks up the pressure changes as electrical signals  Signal can be analyzed and used to determine how much gas is present What is Quartz-Enhanced Photoacoustic Spectroscopy? Laser beam being focused through a quartz tuning fork. (Image credit: http://www.lac.tu- clausthal.de/uploads/pics/e6f892c b11.jpg)http://www.lac.tu- clausthal.de/uploads/pics/e6f892c b11.jpg

5.  Many associated electronics can be simplified and compacted into smaller circuits  Example: laser modulation  Normally done by various pieces of software and instrumentation  For certain types of gas, LEDs can be used instead of lasers  Lower power draw  Safer Key Points for Development

6.  Calibration of laser for methane sensor  Assessment of optimum LED for use in ozone detection  Development and test of circuits for use in tandem with the quart tuning fork for a nitric oxide sensor Summary of work

7.  Contribution in developing trace gas sensors  Valuable skills: problem-solving, working efficiently, theoretical knowledge to reality  Hands-on as well as theoretical knowledge  Learning to interact with international colleagues in a foreign environment  Future prospects: continuing work in electronics and laser spectroscopy at Princeton Afterthoughts

8.  Michael Köhring  Mario Mordmüller  Tassilo Söldner Acknowledgements

9. Questions? Thank you for your attention!