Medical devices take design tips from the animal kingdom
Friday, August 25th, 2023
Millions of years of biological evolution has aided the animal kingdom to adapt processes and characteristics to meet specific needs. Using bioinspiration approach, scientists and engineers are employing insights from biology to solve today’s technological challenges and optimize the design of new materials, devices and structures. For example, researchers have designed a surgical imaging system based on the amazing eyes of the mantis shrimp in the medical field. Just last month saw the publication of two new research studies exploiting insights from biology for the benefit of human health.
Powered by pangolin scales
First up, the pangolin – the solitary mammal that’s entirely covered in hard scales. Rather than to each other, these scales connect to the underlying skin, and overlap in the style of a pine cone, allowing the pangolin to curl into a ball when threatened. It is these scales that provided the inspiration for designing a miniature soft medical robot to Metin Sitti from the Max Planck Institute for Intelligent Systems and his collaborators.
Untethered magnetic soft robots have the potential to accomplish minimally invasive medical procedures inside the body. In future, guided by magnetic fields such robots could be sent to hard-to-reach regions where they can then deliver drugs or create heat. Localized heating can stop bleeding, cut tissue or even ablate tumours. Remote generation of heat, nonetheless, requires the use of rigid metallic materials, which can compromise the compliance and safety of soft robots.
“To address this inherent trade-off between effective remote heating at long distances and compliance, we observed how pangolins in nature could still achieve flexible and unencumbered motion despite having keratin scales which are orders of magnitudes harder and stiffer than the underlying tissue layers, simply by organising the keratin scales into an overlapping structure,” write the researchers, in Nature Communications.
With this in mind, Sitti and colleagues designed and fabricated a 20 x 10 x 0.2 mm robot containing a soft polymer layer and a pangolin-inspired layer of overlapping metal elements. When researchers exposed robot to a high-frequency magnetic field, the robot delivered on-demand heating (by over 70°C) at large distances (more than 5 cm) within less than 30 s. By exposing it to a low-frequency magnetic field, the researchers could make it roll up and move about.
Emulating the octopus bite
“The predatory behaviour of the blue-ringed octopus inspired us with a strategy to improve topical medication,” writes a research team headed up at Zhejiang University and Sichuan University in China. In intratissue tropical medication, challenges like adhering drug carriers to soft tissue surfaces wetted by bodily fluids and controlling the concentration of drug release is faced. To overcome these impediments, first author Zhou Zhu and colleagues created a microneedle patch that facilitates robust tissue surface adhesion and active-injection drug delivery. Writing in Science Advances, they state that the drug-releasing microneedles work in a manner “inspired by the teeth and venom secretion of the blue-ringed octopus”.