An FBG-Based Soft Wearable System for Force Monitoring During Lymph Node Palpation

Force (F) sensing plays an essential role in a wide range of medical application, contributing to the safety and effectiveness of procedures. In recent decades, fiber Bragg grating (FBG) sensors emerged as a promising technology for F sensing, thanks to their great potentials, like small size, multiplexing capability and excellent metrological properties. Despite these advancements, FBG-based F detection is still under-explored in some clinically relevant scenarios, like tactile sensing and particularly lymph node palpation. It consists of the manual application of F on soft tissues to identify alterations in size and mobility of the lymph nodes. However, this technique is strongly affected by the experience and attention of the examiner, with high risk of misdiagnosis. In this context, integrating quantitative F information into palpation procedures may offer a powerful tool to provide objective insights into clinician-tissue interactions, and support clinical-decision making. This study proposed an FBG-based soft wearable system for F monitoring during lymph node palpation. The wearable system consisted of a flexible sensing element (SE) embedding an FBG, designed to ensure accurate F measurement while minimizing interference with the clinician's tactile perception. The system was designed to be worn on the middle finger and accommodate different finger morphologies through an adjustable dual-handle mechanism. After fabrication and metrological characterization, the proposed wearable system was tested in both simulated and real-world clinical scenarios. The promising results revealed the system's ability to transduce applied F into axial deformations of the embedded FBG during palpation tasks, without impairing the clinician's tactile perception.