Real-Time Acetone Vapor Detection Using Mid-Infrared Nanoporous Membrane

Real-time and non-destructive acetone vapor detection was demonstrated using a miniaturized mid-infrared (mid-IR) sensor. The sensing device was made of ultrathin nanoporous anodic aluminum oxide (AAO) membrane embedded in a polydimethylsiloxane (PDMS) micro-gas chamber. The AAO membrane is transparent in the range of 2.5- $5.5\mu $ m that covers the characteristic acetone vapor absorption bands, thus providing high specificity and sensitivity for acetone vapor detection. Real-time monitoring of acetone vapor pulses was performed at $\lambda $ = 2.9, 3.3, and $3.4\mu $ m. The sensitivity of the AAO membrane increased at a smaller nanopore diameter (D) and a larger pore density (N). A 5 parts per million (ppm) sensitivity was demonstrated utilizing a D = 20 nm AAO with a large surface area (S) of $715 {\mathrm {cm}}^{2}$ . Hence, our compact mid-IR AAO sensor provides a new device platform for in-situ and accurate acetone gas detection.