Bioadhesive for sticking sensors on squishy squid

The lives of most sea creatures remain largely mysterious. Bound to boats or land, researchers rely on sensors to collect data and piece together how marine animals move through their environments. But attaching portable data collectors to small, squishy beasts like squid is incredibly challenging.

“They needed to suture the sensor to those marine animals,” explains mechanical engineer Xuanhe Zhao of the Massachusetts Institute of Technology. Now Zhao has combined forces with T. Aran Mooney, a marine biologist at Woods Hole Oceanographic Institution, to alter a bioadhesive designed for sealing human wounds. They’ve use it to, instead, stick sensors to delicate marine creatures (Nat. Commun. 2024, DOI: 10.1038/s41467-024-46833-4).

The new adhesive is made from a combination of polyacrylic acid, polyvinyl alcohol, and N-hydroxysuccinimide ester. The network of physically cross-linked polyacrylic acid absorbs water off the surface of a squid’s skin. The covalently cross-linked network of polyvinyl alcohol strengthens the material and acts as a scaffold to which the ester can bind. And the ester forms a covalent amide bond to the squid’s skin.

When dry, the material is stiff enough to be preemptively stuck to the back of a sensor. Then, when the prepped sensor is placed on the wet skin of a captured marine animal, the adhesive’s matrix absorbs water and the adhesive becomes jellylike and sticks to the animal’s flexible skin. “It’s similar to double-sided tape,” Zhao says.

After designing and synthesizing samples, Zhao’s students went out with Mooney to test the material. Not only did it adhere exactly as expected, but it also allowed the scientists to gently tag numerous squid in a short amount of time—no stitches required.