Advanced Integrated Optical Devices for Ultrasound Diagnostics

The Lab-on-Fiber technology contributes to the development of compact and minimally invasive biomedical devices. By exploiting the high degree of miniaturization combined with the material biocompatibility, these devices can be integrated inside medical needles and placed into the human body for in vivo diagnosis and treatments, with important advantages in terms of performance, effectiveness, and invasiveness. In this framework, with a look toward high-resolution ultrasound-based diagnostics, a novel Lab-on-Fiber 3D micro-structure for ultrasound detection is analyzed, characterized by a polymeric membrane sustained by six pillars above a single-mode fiber tip. Such a structure essentially works as a Fabry-Perot cavity. Based on the finite element method, our numerical studies demonstrated that optimal geometrical parameters allow tuning the working frequency range up to tens of MHz, achieving sensitivities higher than the standard configurations proposed so far, given by polymeric slabs directly attached above the fiber tip. Two-Photon polymerization techniques enable the direct fabrication of the structure on the optical fiber tip.