Soft Robot Works As An Implantable Ventilator

MIT researchers have developed a soft robot that helps people with diaphragmatic disease breathe by augmenting its natural contractions.

Breathing is as natural as fruits on trees. The diaphragm — the dome-shaped muscle located just below the ribcage — is the major muscle responsible for our ability to breathe. It acts like a slow and steady trampoline, pushing down to create a space for the lungs to expand and take in air, then relax as the air is exhaled. But when the function of the diaphragm is compromised, the instinct to breathe becomes a laborious task.

Chronic diaphragm dysfunction can occur in people with ALS, muscular dystrophy, and other neuromuscular diseases, and damage to the phrenic nerve, which stimulates the diaphragm to contract.

The MIT team has developed a soft, robotic, and implantable ventilator designed to augment the diaphragm’s natural contractions. At the heart of the system are two soft, balloon-like tubes that can be implanted to place over the diaphragm. When inflated by an external pump, the tubes act as artificial muscles to push against the diaphragm and help the lungs expand. The pipes can be raised at a frequency to match the natural rhythm of the diaphragm.

The researchers tested the system in anesthetized pigs, implanted tubes in the animals’ diaphragms, and surgically attached the ends of the tubes to the ribs at either end of the muscle. They monitored the animals’ oxygen levels and observed their diaphragm function using ultrasound imaging.

The team found that the implantable ventilator increased the pigs’ tidal volume, or the amount of air taken into the lungs with each breath. The most significant improvement was seen in cases where the contractions of the diaphragm and the artificial muscles coincided. In these cases, the ventilator assists the diaphragm in drawing three times the amount of air than without assistance.

The team is working to optimize various aspects of the system, with the goal of one day implementing it in patients with diaphragm dysfunction.