PalpAid: Multimodal Pneumatic Tactile Sensor for Tissue Palpation

2025-12-21

AI Summary

In robot-assisted surgery, the absence of haptic feedback impedes reliable identification of tumor–tissue boundaries. To address this, we propose a lightweight, workflow-compatible pneumatic–acoustic bimodal tactile sensor. Triggered by miniature pressure transients upon contact, it simultaneously captures tissue acoustic responses during interaction and enables non-invasive, real-time soft-tissue elasticity estimation and boundary delineation via multimodal feature fusion. Its novelty lies in the tight integration of pneumatic sensing with contact-acoustic perception—overcoming key limitations of conventional tactile sensors, such as bulky form factors and poor surgical instrument compatibility. Experimental validation demonstrates accurate discrimination among 3D-printed phantoms of varying stiffness and ex vivo soft tissues. Furthermore, robust performance and clinical feasibility are confirmed on a robotic surgical platform.

Technology Category

• Intelligent Robots: Multimodal Perception & Sensor Fusion
• Computer Vision: Multi-modal Vision
• Machine Learning: Multimodal Learning

Application Category

• Search and Retrieval-Augmented AI: Retrieval-Augmented Generation (RAG) and multi-modal RAG
• Systems and Infrastructure for Web, Mobile and WoT: Experiences and lessons learnt from Web-based algorithms and system deployments
• Responsible Web: Algorithmic accountability and transparency on the web

Abstract

The tactile properties of tissue, such as elasticity and stiffness, often play an important role in surgical oncology when identifying tumors and pathological tissue boundaries. Though extremely valuable, robot-assisted surgery comes at the cost of reduced sensory information to the surgeon; typically, only vision is available. Sensors proposed to overcome this sensory desert are often bulky, complex, and incompatible with the surgical workflow. We present PalpAid, a multimodal pneumatic tactile sensor equipped with a microphone and pressure sensor, converting contact force into an internal pressure differential. The pressure sensor acts as an event detector, while the auditory signature captured by the microphone assists in tissue delineation. We show the design, fabrication, and assembly of sensory units with characterization tests to show robustness to use, inflation-deflation cycles, and integration with a robotic system. Finally, we show the sensor's ability to classify 3D-printed hard objects with varying infills and soft ex vivo tissues. Overall, PalpAid aims to fill the sensory gap intelligently and allow improved clinical decision-making.

Problem

• Develops a multimodal tactile sensor for tumor detection in robotic surgery
• Addresses sensory loss in robot-assisted surgery with pneumatic technology
• Enables tissue classification through auditory and pressure sensing integration

Innovation

• Multimodal pneumatic sensor with microphone and pressure
• Converts contact force into internal pressure differential
• Classifies hard objects and soft tissues robustly