New skin-like material could revolutionize infection testing

In the holiday film The Grinch, makeup artists reportedly spent several hours each day covering Jim Carrey’s face with prosthetics to create the iconic grumpy, green creature. Such elaborate prosthetics, often made possible by materials like silicone rubber, may now have found an unexpected but beneficial biomedical engineering application, according to a new study from Texas A&M University.

Published in the journal Scientific Reports, Researchers created realistic skin-like replicas from Ecoflex, a type of silicone rubber that can serve as a platform for assessing the risks of bacterial infections from intravenous catheters and testing wearable sensors, among other biomedical applications. The study found that skin replicas based on EcoFlex can be made to mimic real skin texture, wettability and elasticity, simulating the conditions where bacteria grow and attach.

We believe the material holds tremendous promise for studying insertion site infections due to naturally occurring bacteria on the skin. Our goal was to create a leather-like material with off-the-shelf ingredients. Ecoflex is not only easy to use, it can be cured quickly with minimal additional steps, making it very convenient.”

Majed Othman Althumayri, a graduate student in the Texas A&M Department of Biomedical Engineering and lead author of the paper

There are approximately one million bacteria per square centimeter of human skin. The most common of these is Staphylococcusespecially the genre Staphylococcus epidermidiswhich is considered a typical inhabitant of the skin microbiome. Infections often occur when there is a cut, break or wound in the skin, allowing bacteria to enter the bloodstream. In fact, a relatively common infection in hospitals comes from surgical insertion of tubes or catheters into veins. Each year, approximately 80,000 catheter-related bloodstream infections occur in intensive care units alone, underscoring its importance to public health in the United States.

“We have been slow to find solutions to prevent infections from intravenous catheters,” Althumayri said. “One reason could be that we don’t have good platforms to test new catheter designs or wearable biosensor technologies and train staff to reduce the number of infections.”

To address this gap, the researchers turned to Ecoflex 00-35, a biocompatible, fast-curing rubber used for a variety of applications, including special effects prosthetics. First, they created molds of common IV sites, such as the elbows, hands, and arms. Then, by pouring Ecoflex into molds containing artificial bones and tubes that acted as veins, the researchers created skin-like replicas.

The researchers then tested whether the Ecoflex leather replicas had properties that matched those of real leather. They measured the replicas’ wettability, bacterial adhesion, and mechanical properties such as elasticity and springiness. The researchers found that the Ecoflex models could reproduce the roughness of human skin within a margin of error of 7.5%. In addition, the high-resolution imaging showed that bacteria could attach to the skin replica and grow on it.

Then, in a key experiment, the researchers simulated an intravenous catheter insertion in a replica of the Ecoflex hand they created. This artificial hand effectively modeled phases of bacterial growth, promising that these replicas can be used to implement infection control measures and improve the design of medical devices such as catheters.

However, the researchers noted that their current experiments do not fully model real-world conditions.

“Developing realistic skin models that can mimic human skin is an important initial step,” said Dr. Hatice Ceylan Koydemir, corresponding author on the study and assistant professor in the Department of Biomedical Engineering with a research program housed at the Texas A&M University Center. for Remote Health Technologies and Systems. “But we believe that incorporating additional evidence, such as body fluids and other clinically relevant conditions, in future experiments will strengthen our findings and further validate Ecoflex’s potential for medical applications.”

Other contributors to the research include Azra Yaprak Tarman, a graduate student in the Department of Biomedical Engineering.

This study was funded in part by the National Institute of General Medical Sciences (one of the National Institutes of Health), the Department of Defense Office of Naval Research, and the National Science Foundation-funded PATHS-UP Engineering Research Center. The researchers also received additional support from the Department of Biomedical Engineering, the Center for Remote Technologies and Health Systems, the Texas A&M Engineering Laboratory, the AggieFab Nanofabrication Facility, and the Soft Materials Facility.