Development of Photoacoustic Sensing Platforms

Research focuses on sensor miniaturization and detection of chemical targets both proximally and at range.

Army Research Laboratory, Adelphi, Maryland

In recent years, photoacoustic spectroscopy (PAS) has emerged as an attractive and powerful technique well suited for sensing applications. The development of high- power radiation sources and more sophisticated electronics, including sensitive microphones and digital lock-in amplifiers, have allowed for significant advances in PAS. Furthermore, photoacoustic (PA) detection of IR absorption spectra using modern tunable lasers offers several advantages, including simultaneous detection and discrimination of numerous molecules of interest. Successful applications of PAS in gases and condensed matter have made this a notable technique and it is now studied and employed by scientists and engineers in a variety of disciplines.

PAS is a detection technique under the umbrella of photothermal spectroscopy. Photothermal spectroscopy encompasses a group of highly sensitive methods that can be used to detect trace levels of optical absorption and subsequent thermal perturbations of the sample in gas, liquid, or solid phases. The underlying principle that connects these various spectroscopic methods is the measurement of physical changes (i.e., temperature, density, or pressure) as a result of a photo-induced change in the thermal state of the sample. Other photothermal techniques include photothermal interferometry (PTI), photothermal lensing (PTL), and photothermal deflection (PTD).