Soft robotics technologies to treat laryngeal disorders

Abstract

Laryngeal disorders may be caused by infection, stroke and injury from surgery or trauma. The condition can be extremely uncomfortable and, in extreme cases, life threatening. Symptoms include hoarseness, shortness of breath, pain in the throat and dangerous aspiration of food and liquids. The discomfort, difficulties in coughing and changes in voice quality can have a significant negative impact on quality of life.

To address the limitations of current surgical and non-surgical solutions, this research aims to investigate new soft robotic solutions for treating severe laryngeal disorders such as vocal fold paralysis, as well as to improve quality of life after surgery such as laryngectomy. This thesis establishes a paradigm for future studies in the development of medical devices for respiratory support and presents four main contributions:

Firstly, a respiratory simulator was designed and built to simulate human breathing and coughing. This simulator provides a powerful platform to advance the development of novel treatments, prostheses and therapies. The comparison between physiological values of breathing and coughing and the values achieved utilising the respiratory simulator shows that the latter is able to accurately reproduce peak flow rates and volumes.

Secondly, a novel assistive coughing device, CoughAid, was developed to mimic the function of the glottis and trachea in the upper respiratory system. Experimental results show a significant increase in peak cough flow rate and peak cough pressure among 33 control participants using CoughAid. Preliminary results with a smaller cohort of post laryngectomy patients show improvement in peak cough pressure using CoughAid. Applications of CoughAid include simulation of vocal folds and respiratory conditions, and as a test-bed for the development of medical devices for respiratory support.

Thirdly, the physiology of vocal folds was studied, which identified that the kinematics of vocal folds and their associated cartilages are not well understood in the literature. A motor-controlled mechanical model of the arytenoid cartilage was designed and built for the visualization of vocal folds movement. Artificial vocal folds using soft material were fabricated for benchtop testing of assist device prototypes without cadaver or animal models.

Lastly, soft fluid-driven actuators were investigated to provide a potential soft actuating method in the human body. A bellows-shaped single balloon actuator was fabricated and tested in a pig larynx to quantify forces that are required for vocal fold adduction. Novel bistable balloon actuators were designed and prototyped which exploit the snap-through phenomenon. These were experimentally characterised in pressurized chambers and demonstrated controllable and stable actuation in tissue substitutes.

Date of Award	21 Jan 2021
Original language	English
Awarding Institution	The University of Bristol
Supervisor	Jonathan M Rossiter (Supervisor) & Andrew T Conn (Supervisor)