The history of science is filled with examples of simple solutions being found for complex problems. Often, these solutions are discovered by serendipity, i.e., by chance and to the pleasant surprise of the scientist – but it is worth remembering the words of Louis Pasteur: “Chance favors the prepared mind”.
In our lab at the University of Maryland, we emphasize simplicity. We work with soft, nanoscale materials, and we seek to achieve new properties in as simple a way as we can. Many of our discoveries have arisen through serendipity. One class of materials we study frequently are ‘hydrogels’ (an example is Jell-O). Recently, two Ph.D. students in our lab, Leah Borden and Ankit Gargava, were experimenting with the effects of electric fields on hydrogels. Leah decided to take it a step further and decided to examine how these gels would behave when contacted with animal tissues.
For these experiments, Leah went to a local butcher and procured tissue from cows. She took a piece of the bovine aorta (which is one of the main arteries connected to the heart) and contacted it with a gel made in the lab. When a low DC voltage (10 Volts) was applied to this sandwich for a short time (20 seconds), to our pleasant surprise, we found that the gel had become strongly stuck to the tissue (Fig. 1). This adhesion persisted when the field was removed, and because it was induced by the field, we call it ‘electroadhesion’. Interestingly, if we re‑applied the field after reversing the polarity, the gel became unstuck from the tissue. So, electroadhesion is both strong and also reversible!
Fig. 1. Electroadhesion of a gel to bovine aorta.
Our experiments have revealed that electroadhesion works with many, but not all, tissues of the cow. The tissues it does work with include the aorta, cornea, lung, and cartilage. These results are described in our recent paper . We still have to figure out why these differences between tissues arise. It may have to do with the charge on the tissues, which in turn depends on their protein content.
The moment we discovered electroadhesion between gels and tissues, we recognized the potential importance of our findings – that this technique could be used to perform surgeries in the future. Currently, when there is a cut or tear in a tissue, such as in a blood vessel or the intestine, an expert surgeon performs the repair. The surgeon uses sutures or staples to rejoin the torn pieces, and the body then repairs the injury over time. These surgical procedures are difficult and expensive. Adhesives have been explored as alternatives to sutures, but current surgical adhesives are not sufficiently strong to join cut tissues.
Could electroadhered gel patches allow surgeries to be done without sutures? We have explored some in vitro aspects related to this question in our paper . For example, we made a tube from biopolymers and cut it in half (Fig. 2). We then electroadhered a gel strip around the cut halves and showed that the repaired tube remained intact while allowing liquid to flow through its lumen. This is similar to a surgical procedure called an ‘anastomosis’.
Fig. 2. Using electroadhesion to repair a severed biopolymer tube.
There are many notable points about electroadhesion. It is very simple: all you need is a gel that is easy to make, and additionally you can make do with just a battery for the DC power. Adhesion can be achieved upon the flick of a switch! And if there is a mistake, the adhesion can be reversed and you can start all over. Conversations we have had with surgeons all indicate that they are excited to apply this technique in animal models, which will be our focus in the near future. We are indeed aware that there are many challenges – we have to ensure that a gel used for surgery is non-toxic, will not trigger the immune system, and will get biodegraded over time. It could be many years before this technology reaches the clinic. Interestingly, our lab has had a recent experience where a product we invented to stop bleeding recently reached the market – but it took more than a decade after the original invention. We look forward to the journey with electroadhesion – it certainly promises to be exciting.
 Leah K. Borden, Ankit Gargava and Srinivasa R. Raghavan. Reversible electroadhesion of hydrogels to animal tissues for suture-less repair of cuts or tears. Nature Communications, 12, 4419 (2021)