Membrane Sensorization for Acoustic Coupling Optimization in a Robotic HIFU Platform

Abstract

High-Intensity Focused Ultrasound (HIFU) surgery is a non-invasive therapeutic technology that allows for precise energy delivery for ablating tumors and treating neurological disorders. Maintaining optimal acoustic coupling between the HIFU transducer and the patient’s skin is essential for treatment efficiency, but the coupling is often compromised by anatomical constraints, patient movements and wrong positioning. Monitoring pressure throughout the membrane would enable acoustic coupling optimization. In this framework, the objective of this study is to develop and validate a novel, acoustically transparent sensorized membrane as a foundational component for acoustic coupling optimization. Various sensors were tested acoustically for ultrasound transparency, with Fiber Bragg Grating (FBG) sensors demonstrating minimal wave reflection. A custom silicone membrane ( $700~\mu $ m in thickness) was fabricated and acoustically and mechanically characterized. Ex vivo HIFU sonication validated the transparency of sensorized membrane, showing no statistically significant impact on lesion formation. Finally, the actual capability of the FBGs optical fiber to sense the contact across all the membrane was validated through indentation tests. By successfully demonstrating the feasibility and performance of this core component, this work establishes a foundation for real-time acoustic coupling optimization systems, paving the way for enhanced HIFU treatment safety and efficacy.