They’re invaluable for their role in preventing unwanted pregnancy and the spread of sexually-transmitted infections, but condoms just don’t feel right. Even in spite of clever marketing, rubbers don’t feel like the real thing, a problem that causes as many as four in ten teenagers to opt out of using them.
But condoms could soon feel a lot more like skin.
In research published in Advanced Healthcare Materials on Monday, a team of materials scientists from Massachusetts Institute of Technology announced that they can use soft, stretchy, slippery “hydrogels” to make condoms — and other medical devices, like catheters or IV tubes — feel way more natural.
“We can replace uncomfortable solutions,” Xuanhe Zhao, the mechanical engineer from MIT who conducted the research, told Inverse.
Zhao and his team developed the hydrogels to manufacture products that feel like the part of the body they contact — say, a catheter that feels like the inside of a urethra, or a condom that feels like the skin of a penis. The reason so many of these products feel terrible, he explains, is that they have such different molecular structures than the part of the body they touch, so they create a lot of friction. Making them more “body”-like requires optimizing two qualities — flexibility and water concentration — to be more like human tissue.
“If you look at the components of the human body, except the teeth, bones or nails, all other components are polymer networks integrated with water,” Zhao says. “We demonstrated that you can reduce the friction by several times.”
He plans to coat existing silicone or rubber materials with his new hydrogel in order to make devices feel like the real thing.
Existing medical tubing has no water content, so it causes much more friction than a hydrogel. This can cause discomfort and pain, especially depending on how it’s used. Zhao’s hydrogel-rubber hybrid combines the best of both materials; not only will the hydrogel coating increase comfort and flexibility while removing the risk of an allergic reaction to silicone, but the sturdier core will prevent any harmful chemicals or viruses from filtering through the softer outer layer.
But his new hydrogel goes beyond manufacturing condoms that people will actually want to wear. Since developing these hydrogels, Zhao’s lab has looked into more and more materials so that they can be used for all sorts of medical devices. For example, he envisions using a hydrogel to make a safer neural probe.
Zhao explains that common medical devices are made from rigid metals, glass, or silicone. “Soft tissues like brain, muscles, if you put these things together it’s not very compatible,” he says. “Rigid materials can actually damage soft tissues. So our strategy is to replace the rigid materials with something with almost the exact properties and composition as those tissues.” Basically, Zhao wants to make sure that doctors don’t cause more harm than they need to during medical procedures. His ultimate goal is to create a “seamless interface for long-term compatibility.”
So if you’re not a fan of suiting up before a night of romance, rest easy, because these hydrogels might help you find a seamless interface and some long-term compatibility of your own.
Hydrogels have been proposed for sensing, drug delivery, and soft robotics applications, yet most of these materials suffer from low mechanical robustness and high permeability to small molecules, limiting their widespread use. This study reports a general strategy and versatile method to fabricate robust, highly stretchable, and impermeable hydrogel laminates via hybrid lamination of an elastomer layer bonded between hydrogel layers. By controlling the layers’ composition and thickness, it is possible to tune the stiffness of the impermeable hydrogels without sacrificing the stretchability. These hydrogel laminates exhibit ultralow surface coefficients of friction and, unlike common single-material hydrogels, do not allow diffusion of various molecules across the structure due to the presence of the elastomer layer. This feature is then used to release different model drugs and, in a subsequent experiment, to sense different pH conditions on the two sides of the hydrogel laminate. A potential healthcare application is shown using the presented method to coat medical devices (catheter, tubing, and condom) with hydrogel, to allow for drug release and sensing of environmental conditions for gastrointestinal or urinary tract.