Embryo viscoelasticity measurement by fiber-optic system: System development and model experiment

To establish a non-invasive measurement method for human embryo viability, we studied the fiber-optic dynamic viscoelasticity measurement system. We measured the dynamic viscoelasticity of the gelatin gel model by optical monitoring of the displacement, stress and their phase difference. We measured the reflected light power change of the model surface by a single optical fiber to obtain the displacement of the surface. The dimensions of the gelatin cube model were 1×1×1 cm. A He-Ne laser with 632.8 nm in wavelength was used as a illumination light source. A thin single optical fiber with 200 μm in core diameter was used both for the illumination and detection. A solenoid-actuator was used to vibrate the model. In the surface displacement ranging from 230 μm to 400 μm, we carried out the linear relation between the reflected light power change and displacement. We measured the dynamic viscoelasticity in gelatin concentration from 2.5 % to 7.5 %. Since the dynamic viscoelasticity of the gelatin increased linearly with increasing of the gelatin concentration, the displacement obtained by the reflected light power measurement can be applicable to obtain the dynamic viscoelasticity. We demonstrated that the efficacy of the novel simple non-invasive dynamic viscoelasticity measurement using the thin optical fiber. This system may be applicable to live embryo measurement with minor reconstruction.