A biodosimeter based on thermal-induced elastic shear wave (TIESW) in silicone acellular porcine dermis (SAPD) at thermal steady state has been proposed and demonstrated. A square slab SAPD treated with ionizing radiation was tested. The SAPD becomes a continuous homogeneous and isotropic viscoelastic medium due to the generation of randomly coiled collagen fibers formed from their bundle-like structure in the dermis. A harmonic TIESW then propagates on the surface of the SAPD as measured by a nanometer-scaled strain-stress response under thermal equilibrium conditions at room temperature. TIESW oscillation frequency was noninvasively measured in real time by monitoring the transverse displacement of the TIESW on the SAPD surface. Because the elastic shear modulus is highly sensitive to absorbed doses of ionizing radiation, this proposed biodosimeter can become a highly sensitive and noninvasive method for quantitatively determining tissue-absorbed dosage in terms of TIESW’s oscillation frequency. Detection sensitivity at 1 cGy and dynamic ranges covering 1 to 40 cGy and 80 to 500 cGy were demonstrated.
Viscoelastic shear waves (VESW) propagation in soft matters such as gelatin under thermal steady state was studied. VESW in a slab of gelatin causes the transverse displacement of the surface in a harmonic wave. The harmonic oscillation frequency of the transverse displacement of gelatin surface was then measured in real time in order to measure the modulus of rigidity of gelatin in terms of the measured oscillation frequency. A polarized heterodyne interferometer (PHI) was setup in this experiment which enables to precisely measure the transverse displacement of surface in real time at 0.3 nm resolution. This results in the proposed VESW method able to characterize gelatin soft material in real time. From the experimental demonstration, the properties of VESW propagation in soft material at thermal steady state potentially can become a novel nano-scale non-intrusion strain-stress sensor able to characterize the modulus rigidity of soft material.
Degree of coherence (DOC) of a paired surface plasma waves (PSPWs) in the paired surface plasma waves biosensor (PSPWB) is proposed and discussed in which a paired of surface plasma waves are excited by using a pair of highly spatial and temporal correlated P-polarized waves in a SPR device of the Kretschmann configuration. The heterodyne signal from reflected paired P-polarized laser beam is generated where the visibility of the signal is proportional to DOC of PSPWs in term of the ratio of AC and DC components of the signal. The experimental result shows that the DOC of PSPWs versus incident angle of laser beam which relates to intrinsic phonon distribution in metal film becomes much sensitive than conventional amplitude or intensity sensitive surface plasmon resonance (SPR) biosensor. Finally, the dynamic range of protein-protein interaction at ultralow concentrations is discussed.