Burn Chamber Test of Ex Situ Thermal Impulse Sensors

Recently, we reported on a novel ex situ thermal impulse sensing technique (based on lanthanide-doped oxide precursor nanoparticles) for use in structural fire forensics and demonstrated its functionality in small-scale lab-based tests. As a next step we have now performed a large-scale lab test at the US Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF) Fire Research Laboratory using a burn chamber with three sand burners. In this test we demonstrate our technique's ability to determine the average temperature experienced by surfaces during the fire. While we successfully demonstrate our techniques accuracy, we also discover several previously unknown vulnerabilities. Namely, we find that: (1) our current method of embedding sensors in paint results in our sensor particles being difficult to recover (due to a large quantity of debris), (2) the current test panels have poor survivability, (3) debris from the fire tests interferes with excitation of dopant Dy ions (limiting our sensors' functionality), and (4) dispersal in paint results in suppression of the (metastable)tetragonal-to-monoclinic phase transition of ZrO₂. To overcome these vulnerabilities we are evaluating new panel materials, paints, and lanthanide-dopants.