Using Attenuated Total Reflection (ATR) to Investigate the Temperature Dependent Dielectric Properties of Tympanic Membrane, Ear Canal, and Muscle tissues

The attenuated total reflection (ATR) setup, equipped with a diamond crystal and operating in a mixed reflection/transmission mode, demonstrated a superior and efficient capacity for investigating temperature-related interactions of biological materials at the THz-far infrared beamline at the Australian Synchrotron. This methodology was employed explicitly to investigate the temperature-driven variations in reflectance of biological tissues, such as the tympanic membrane, skeletal muscle, and brain samples, in addition to the interaction of water with THz radiation. Uniquely, the technique detected a characteristic ‘crossover flare’ feature in the spectral scan, a trait inherent to water and water-based compounds. It also identified a ‘quiet zone’ feature, a region exhibiting no temperature-dependent reflectance variation at higher frequencies. Remarkably, this approach required minimum sample preparation and was non-destructive, enabling the investigation of a range of tissue temperatures to ascertain the influence of temperature on the reflection and absorption dynamics of THz radiation. ### Competing Interest Statement The authors have declared no competing interest.