# A Single-Sensor Approach for Noninvasively Tracking Phase Velocity in Tendons during Dynamic Movement

## TL;DR

This paper introduces a new noninvasive method using a single sensor to track wave speed in tendons during movement, offering a simpler and more versatile alternative to traditional methods.

## Contribution

The novel approach uses shaped excitations and a single sensor to measure phase velocity in tendons.

## Key findings

- Phase velocity in the Achilles tendon was consistent with traditional broadband excitation methods.
- Phase velocity showed frequency dependence, as expected in dispersive soft tissues.
- The method enables smaller, more versatile shear wave tensiometers for broader applications.

## Abstract

Shear wave tensiometry is a noninvasive method for directly measuring wave speed as a proxy for force in tendons during dynamic activities. Traditionally, tensiometry has used broadband excitation pulses and measured the wave travel time between two sensors. In this work, we demonstrate a new method for tracking phase velocity using shaped excitations and measurements from a single sensor. We observed modulation of phase velocity in the Achilles tendon that was generally consistent with wave speed measures obtained via broadband excitation. We also noted a frequency dependence of phase velocity, which is expected for dispersive soft tissues. The implementation of this method could enhance the use of noninvasive wave speed measures to characterize tendon forces. Further, the approach allows for the design of smaller shear wave tensiometers usable for a broader range of tendons and applications.