Recently, Chinese researchers have developed a novel terahertz photoacoustic system, marking a significant step forward in non-invasive diagnostics. This system overcomes water interference, eliminating the need for blood draws or labeling, and enables real-time measurement of sodium levels in live mice. Preliminary human trials have also demonstrated its potential and feasibility for clinical applications.
Terahertz waves, located between microwave and mid-infrared bands, offer advantages such as low energy, tissue harmlessness, weak scattering, and high sensitivity to biological structural changes—making them an ideal tool for biomedical detection. However, terahertz waves are easily absorbed by water, posing two major challenges for biomedical applications: eliminating interference from water molecules in complex samples and achieving in vivo detection through thick biological tissues.
Accurate blood sodium measurement is crucial for diagnosing and treating dehydration, kidney diseases, and certain neurological/endocrine disorders. The research team developed a detection system combining photoacoustic sensing with terahertz spectroscopy, allowing long-term non-invasive monitoring of blood sodium concentration.
The system emits terahertz waves through a modular setup, exciting sodium ions in the blood to generate ultrasonic waves, which are then captured by an ultrasonic transducer. This photoacoustic technique converts absorbed terahertz energy into sound waves, effectively overcoming water absorption interference. It enables long-term, label-free monitoring of blood sodium levels in live mice, with human volunteer trials also yielding promising results.
“In the future, this system could not only detect blood sodium but also identify other ions like potassium and calcium, as well as biomolecules such as sugars, proteins, and enzymes through their terahertz absorption signatures, showing broad development potential.”
