# A Wearable Ultrasound Sensing System for Soft Tissue Stiffness Detection: A Feasibility Study

## TL;DR

This study introduces a wearable ultrasound system to objectively measure soft tissue stiffness, improving upon subjective manual palpation methods.

## Contribution

A novel wearable system using ultrasound time-of-flight differences to monitor tissue stiffness in real-time is developed and tested.

## Key findings

- A correlation model between ultrasound time-of-flight differences and tissue stiffness was successfully established.
- The wearable system can detect stiffness changes in human muscles during contraction and relaxation.
- The system was validated on silicone samples and ex vivo tissues before testing on human subjects.

## Abstract

Manual palpation serves as a conventional clinical method for assessing soft tissue stiffness; however, its results are susceptible to subjective factors and exhibit limited reliability. To achieve objective evaluation of pathological tissue stiffness, this study utilizes ultrasonic transducers to measure the time-of-flight (ToF) difference in ultrasound signals in silicone samples and ex vivo animal tissues under specific pressure gradients. A correlation model between the ToF difference and tissue stiffness was established, thereby enabling the detection of tissue stiffness. Based on this methodology, a wearable sensing system incorporating ultrasonic transducers was developed. The system applies fixed gradient pressure to human tissues via a pneumatic control unit and detects the corresponding ToF difference, allowing real-time monitoring of stiffness variations in the biceps brachii and thigh during relaxation and contraction, in the forearm during gripping and release actions, as well as in simulated lesions. This study provides a quantitative technological framework for wearable tissue stiffness monitoring, and its objective measurement characteristics offer support for clinical diagnostic decision-making.