Octopus suckers inspire sticky medical patch

A reusable medical patch that uses octopus-like suckers to stick to skin can monitor a range of vital signs — and could put an end to the skin injuries caused by traditional adhesive patches, including skin inflammation, tension injuries, blisters, and tears^[1].

“The patch is designed for easy removal without causing discomfort or pain, unlike conventional glue-based patches,” says Nazek El-Atab, who led the team that developed it.  “Our goal is to develop a comprehensive, versatile, skin-attachable device that can revolutionize wearable health monitoring and diagnostic technologies.”

Clinicians routinely use adhesive patches to attach medical devices to patients. These devices might record pulse rate or muscle response, for example, or deliver vital medicines through the skin. Many patches rely on chemical adhesives, but these glues can cause a range of side effects for the skin.

Inspired by the circular suckers found on octopuses’ arms, KAUST researchers have developed a way to rapidly and cheaply create medical patches that carry ‘adhesive miniaturized octopus-like suckers’ (AMOS). The patches are flexible, biocompatible, and breathable, and carry an electrode that can monitor several types of biosignal.

“Previous bioinspired suction-based adhesives have suffered primarily from limited manufacturing flexibility and versatility due to traditional nano-/microfabrication techniques,” explains Aljawharah A. Alsharif, a Ph.D. student under the supervision of El-Atab.

“Other bio-inspired patches that adhere using suction mechanisms tend to face challenges when it comes to manufacturing: traditional nano-/microfabrication techniques limit the required manufacturing flexibility and versatility to produce them. Typically, these adhesives feature tiny hollows or ridges measured in millionths or even billionths of a meter and so fabricating materials with these finely detailed structures can be expensive. Also, they may only be effective on certain types of skin surface.

 The AMOS patch overcomes these limitations by using a rapid hybrid 3D printing approach, explains Alsharif. The researchers found that a 3D printing technique called stereolithography could offer the precision they needed to make the AMOS patches. The method uses an ultraviolet laser to accurately build up a resin mold that contains tiny domes and wiggly lines. Then they used that mold to create an AMOS patch from a biocompatible polymer called polydimethylsiloxane (PDMS), which has some inherent stickiness.

After testing patches with different-sized suckers and various patterns, they found that 200 micrometer-wide suckers offered the greatest adhesion. Meanwhile, the patch’s wiggly grooves help moisture escape from the skin, ensuring that the material is highly breathable. “When the patch is lightly pressed on to the skin, the suckers create a vacuum, providing secure adhesion even under various skin conditions such as dry, wet, or hairy surfaces,” says Alsharif. This mode of adhesion also enables the same patch to be reapplied again and again, making it useful for long -erm health monitoring

The researchers fitted the patch with electrodes, attached it to the hairy chest of a male volunteer while he cycled on an exercise bike, and used the device to monitor the subject’s electrocardiogram (ECG) signals. The same patch could also be placed on different parts of the body to record electromyograms (EMG) — which measure muscle response — and electrooculograms (EOG) to monitor eye movements.

The team were also able to ‘road test’ the patch on KAUST computational scientist and associate professor Matteo Parsani. Parsani wore the patch to monitor various biosignals on his 30-day Athar: East to West hand-cycling journey across the kingdom, a distance of more than 3000km.

“The versatility of the AMOS patch allows it to function effectively across different types of biosignal measurements simultaneously, demonstrating its broad applicability and efficiency in biomedical applications,” says Alsharif. “It can also be reused multiple times without significant loss of adhesion.”

The researchers now aim to apply AMOS patches to other measurements, including temperature, glucose and stress levels. “We plan to conduct extensive clinical trials to validate its efficacy in real-world medical applications,” says El-Atab.

The team is also collaborating with other research groups to expand the range of applications for the AMOS patch in other wearable health technologies, says El-Atab.