About This Project

Ostomy bags are a daily medical necessity for 15 million people globally. However, these bags often delaminate from the skin, causing problematic leaks and requiring frequent bag replacement. Delamination between a flat adhesive bandage and a rounded stomach fundamentally results from an elastic buckling process driven by the geometric and elastic mismatches of the two components. The purpose of this study is to characterize this process to facilitate the design of better bags.

Ask the Scientists

What is the context of this research?

Ostomy bags are a daily medical necessity for roughly 15 million people globally who have had a section of intestinal tract removed, resulting in the intestine being rerouted through the abdomen where waste is ejected via a stoma. These bags adhere to a section of skin surrounding the stoma via an annular adhesive bandage, collecting waste and shielding the stoma from the broader environment. This serves to reduce infection while minimizing changes to the daily life of the patient. However, these bags are expensive making them inaccessible for lots of people, especially in underdeveloped countries. Also, the bags often delaminate from the skin, causing problematic leaks which lead to skin irritation and poor quality of life.

What is the significance of this project?

Delamination between a flat adhesive bandage and a rounded stomach (objects with intrinsically different Gaussian curvatures) results from a competition between adhesion and an elastic buckling process driven by the geometric and elastic mismatches of the bandage and substrate. This process is well characterized for a flat disk conforming to a rigid spherical substrate, but ostomy bags are necessarily annular while the abdomen is nonrigid and dynamically changes shape. The purpose of this study is to characterize the delamination process of ostomy bags from a substrate of varying shape as a function of their respective geometric and material properties. This work can then be extended to design a new class of low-cost ostomy bags that frustrate the delamination process.

What are the goals of the project?

We will run ostomy bags adhered to a human skin mimic through a representative set of shape, size, and curvature changes to characterize the delamination modes an ostomy bag typically takes. These shape changes can be effected via a linear stepper motor, custom 3d printed parts, and custom cast PDMS substrate base. We can backlight the ostomy bag to capture regions of delamination in sharp contrast on a color camera and analyze how the regions grow or change as the substrate cycles through a set of shapes repeatedly. With a comprehensive dataset of the most common failure modes, we can then test new bag designs which resist these modes using the same experimental apparatus.