A MEMS on Fiber Multisensor Platform for Surgical Assistance

We developed a microelectromechanical system for simultaneous temperature and pressure measurements, which is integrated on a fiber. The developed platform is integrated at the tip of a fiber-optic cable for surgical assistance. The platform comprises a three-layer sealed micrometer-scale membrane that deflects in response to external pressure. Moreover, we exploit the change in bandgap wavelength of the gallium arsenide substrate to monitor temperature. The developed multisensor is capable of point-wise and decoupled measurements, owing to its compact form factor and different physical principles used for sensing of temperature and pressure. Both sensors are interrogated using a multimode fiber that is butt-coupled to the substrate, allowing for simple integration and alignment as opposed to a single-mode fiber. Furthermore, the exploitation of graded index in the fiber core enables measurement immunity to fiber bending. Experiments were conducted in a pressure chamber and on ex vivo tissue. We measured sensitivities of 9.04 nm/mmHg in displacement for pressure and −1.38%/°C in optical power for temperature. With further development, the proposed device can be adapted to a clinical setting as an assistive tool during ablative medical operations, in determining ablation boundaries while monitoring intravascular or organ pressure as a vital signal.