Ear Tubes
Ear Tubes
Infections of the middle ear, the air-filled space behind the eardrum that contains the tiny vibrating bones of hearing, annually affect more than 700 million people worldwide. Children are especially prone to ear infections, with 40% of them developing recurrent or chronic infections that can lead to complications like impaired hearing, speech and language delays, perforations in their eardrums, and even life-threatening meningitis.
As a treatment, doctors may surgically insert ear tubes knowns as “tympanostomy tubes” (TTs) into the eardrum to create an opening between the ear canal and middle ear. Ideally, these conduits ventilate the middle ear, provide a route for fluid to drain out, and allow antibiotic drops to reach the infection-causing bacteria. But in reality, these small hollow cylindrical devices made of plastic or metal function far from perfectly. Bacteria can lay down biofilms and local tissue can grow on their surfaces, which blocks TTs’ lumen and causes them to extrude. Also, antibiotic ear drops applied in the ear canal may not effectively reach the site of infection behind the eardrum. These complications pose risks and result in the need for frequent replacement surgeries, producing sizeable economic costs to the health care system.
Importantly, problems affecting TTs also plague other fluid-transporting “implantable medical conduits” (IMCs), such as catheters, shunts, and various small tubes with use in the brain, liver, eyes, and other organs where a high-pressure barrier prevents fluids from flowing through the conduit. In the quest for superior devices, the fundamental challenge faced by biomedical engineers is rooted in the conflict that reducing IMC devices’ size and invasiveness comes at the price of increasing their risk of becoming blocked and malfunctioning.
Our approach enables IMCs with predictable and effective uni- and bi-directional fluid transport at the millimeter scale that resist various contaminations. With the example of TTs fabricated from a liquid-infused material (iTTs, short for “infused tympanostomy tubes”), they co-optimized difficult-to-reconcile functions, including fast drug delivery into and drainage of fluids out of the middle ear, resistance against water crossing from the outside into the middle ear, as well as the prevention of bacterial and cell adhesion to tubes, by introducing a novel curved lumen geometry of the tube. The findings are published in the recent cover article of Science Translational Medicine.
Contact: Haritosh Patel