A 3-D-Printed Tactile Probe Based on Fiber Bragg Grating Sensors for Noninvasive Breast Cancer Identification

Tissue palpation is one of the most popular techniques to detect tissue abnormalities in clinical scenarios, including breast examination. However, the tactile sensation used to identify tumors by the clinician or a woman during breast palpation makes this procedure subjective. Over the past decades, tactile sensors have been developed to quantitatively discriminate between cancerous and healthy tissues, but most of these systems still suffer from low force sensitivity, high power consumption, reduced sterilization durability, and electrical noise. This study aims to overcome these limitations by exploiting the advantages of fiber Bragg grating (FBG) technology combined with the ones of 3-D printing to develop an innovative tactile probe for breast cancer identification. FBGs have already been proposed for tissue palpation in minimally invasive surgery via tactile sensing, while their application in superficial palpation is still overlooked. To the best of authors' knowledge, this is the first work in which the FBG integration into 3-D-printed structures is proposed for breast superficial palpation. Here, we first focused on the sensing unit design optimization via finite-element analysis, fabrication, and metrological characterization. Then, the final prototype of the tactile probe integrating multiple identical sensing units was fabricated, and the results of tests on silicone samples with different hardness and on a phantom mimicking breast tissue with an early stage tumor were discussed. The promising findings will guide further optimization of the tactile probe design to improve system spatial resolution, reduce its encumbrance, and provide feedback to the user for applications on patients.