Terahertz optoacoustics of water, tissues and aqueous solutions

Radiation at terahertz frequencies can be used to analyze the structural dynamics of water and biomolecules, but applying the technique to aqueous solutions and tissues remains challenging because such radiation is strongly absorbed by water. Here we develop terahertz optoacoustics as a method for analyzing water, tissues and aqueous solutions even in thick samples. We demonstrate that adjusting the temperature to alter the terahertz optoacoustic signal of water improves the sensitivity with which it can be analyzed and, conversely, can reduce or even "silence" its signal, allowing detection of solutes such as glucose and ions, potentially with greater sensitivity than terahertz time-domain spectroscopy. Terahertz optoacoustics may be a powerful tool for spectroscopy and potentially imaging of aqueous solutions and tissues to study molecular interactions and biochemical processes.