Sensors such as electrocardiogram (ECG) electrodes can help save a person's life, but the adhesive patches used to attach them may also harm that person's skin. An experimental new medical patch addresses that issue by utilizing octopus-inspired suckers.
Most medical patches are much like band-aids, in that they utilize adhesive chemicals – glues, in other words – to temporarily stick to the skin. Unfortunately for many people, their skin becomes irritated by those chemicals, resulting in itching, redness, inflammation and even blisters.
Additionally, the adhesives often fail when they get wet. What's more, it hurts when the patch is removed, and that patch typically won't stick well if it's reapplied.
Seeking a less irritating, less painful and more robust, reusable alternative, scientists from Saudi Arabia's King Abdullah University of Science and Technology (KAUST) have looked to the octopus.
More specifically, they looked to the suckers found along the underside of octopus tentacles. Not only can those suckers repeatedly adhere to surfaces without using any chemicals, they can do so underwater.
To make their "adhesive miniaturized octopus-like suckers" (AMOS) patch, the researchers started by building a mold. This task was achieved using a 3D printing technique known as stereolithography, in which objects are built up by selectively shining an ultraviolet laser into a vat of photo-curable resin.
The resulting mold consisted of an array of tiny domes intertwined with a network of squiggly lines.
Next, a biocompatible polymer called polydimethylsiloxane (PDMS) was applied to the mold in liquid form, then peeled off once it cured to solid elastic form. In the resulting patch, the domes produced tiny suckers, while the lines produced tiny channels that ran out to the edges of the patch.
When the finished AMOS patch was pressed onto human skin, the suckers securely adhered to the surface by forming a tiny vacuum under each one. The fact that PDMS itself has a somewhat adhesive microstructure helped the patch to stick, while still allowing it to be painlessly removed.
The channels, meanwhile, carried moisture out from under the patch by capillary action, helping the underlying skin to breathe.
In one test of the technology, an AMOS patch was equipped with electrodes then adhered to the skin of a male volunteer as he cycled on an exercise bike. The patch stayed in place even when applied to wet or hairy skin, providing good readings without causing any skin irritation.
The technology was even successfully used to monitor the biosignals of a KAUST computational scientist as he completed a 3,000-km (1,864-mile) hand-cycling trip over a 30-day period.
"Our goal is to develop a comprehensive, versatile, skin-attachable device that can revolutionize wearable health monitoring and diagnostic technologies," says the lead scientist, Asst. Prof. Nazek El-Atab. "We plan to conduct extensive clinical trials to validate its efficacy in real-world medical applications."
A paper on the research was recently published in the journal Advanced Functional Materials.
Source: KAUST
