The photoacoustic technique was invented by Alexander Graham Bell in 1880. It can be used to detect gaseous pollutants and for biomedical imaging. The technique works by detecting acoustic signals produced by molecules in a specially designed Photoacoustic (PA) cell. The PA cell acts as a resonance cavity and amplifies weak acoustic waves produced by the absorption of laser radiation.
The current PA sensor has advantages over existing photonics techniques because it uses low-cost acoustic microphones instead of expensive photonics detectors. It can also work in noisy environments due to its selectivity of resonance frequency.
A research team from the University of Hyderabad has successfully designed and developed a high-Q Helmholtz Photoacoustic (PA) cell sensor for detecting the acetone biomarker. The cell’s natural frequency is tunable between 1.4 to 4.4 kHz, and it has an impressive maximum Q factor of 492.3 at 0.11 THz frequency. This is about 10 times higher than existing designs. The innovation is currently being considered for a patent by the DRDO, Ministry of Defence, government of India.
The Helmholtz PA cell is made of aluminium and has proven to be effective in detecting acetone, which is a biomarker for diseases like diabetes, asthma, and lung cancer. The cell has unparalleled sensitivity, being able to detect acetone at levels as low as parts per trillion (PPT). This research shows promise for non-invasive medical diagnostics and could revolutionize disease detection.
The cell can also be used to detect trace explosives, atmospheric pollutants, and volatile solvents. It can be used with UV-VIS, mid-IR, and THz radiation.
The research was published in the recent issue of Spectrochimica Acta A: Molecular and Biomolecular Spectroscopy on July 28, 2023.
