Stick with it - evolving medical adhesives

As medical device design continues to innovate and push forward the boundaries of design and technology, the role of adhesives is changing. Product manufacturers are following suit with formulations that meet the latest needs of today’s devices. By Lu Rahman

While the automotive and aerospace sectors have historically pushed forward innovation in the adhesives sector, the medical market should not be overlooked with increasing technological advancement taking place in this area.

Performance is of course key and as the need for quality medical adhesives becomes ever more important, many manufacturers are looking at this market with interest and producing products that meet the challenges that the medical sector demands. As medical devices become smaller and more lightweight, the trend for adhesives to match this innovation has followed. Device manufacturers are looking to replace fasteners while the materials being used to make these products are becoming more complex requiring a re-think of the adhesive being used to both complete a device and also where necessary, to attach the device to an individual.

Trend setters

Certain trends in the adhesives sector are beginning to emerge and in the medical sector there is an increasing requirement for products that stick to silicones, for example. The wearables sector is becoming highly significant requiring the development of multimaterial adhesives for these layered products which can include touch panels, lights, cameras and of course electronics. They use many different materials and therefore the choice of adhesives becomes more complex.

As traditional methods of fastening such as welding or screwing become harder to use due to the more complicates nature of the components in modern devices, adhesives are really having to come to the fore. Lightweight products using carbon-fibre reinforced plastics make adhesives the only viable way to join as drilling is no longer an option. And for this reason, the choice of adhesive is becoming an early consideration in a product’s design process.

The global adhesives market offers much potential – this year it has been estimated to be worth $11,339.66 million and is projected to grow at a CAGR of about 4.88% between 2015 and 2020. The biggest and fastest growing region is currently the Asia-Pacific with growing demand for adhesives in India, China, Japan, South Korea, and Australia. North America is still also a significant space for medical adhesives.

Industry bonding

DuPont has been working closely with medical display manufacturers for some time offering optical bonding technology to this sector. The company recognises that medical applications require mobility and reliability features in LCDs and that they also present demanding challenges such as ambient lighting conditions, shock, vibration, sterile environmental requirements and constant temperature changes. The company’s Vertak bonding technology has been developed to offer a range of benefits including resistance to stains, dirt and moisture, durability to withstand shock and temperature change and also enable thinner and lighter display designs. Other companies involved in medical adhesive technology include Eastman Chemical Company, Evonik and DOW Chemical Company.

Get a grip

NanoGriptech is another company pushing forward innovation in this field. Strange as it might sound, the company has produced a gecko-inspired adhesive, Setex, that it says is the world’s first dry adhesive inspired by the microscopic hairs of a gecko’s foot.

The technology is being put forward as a solution to a range of medical applications and is said to offer friction enhancement to skin. The company says that current gripping material used on orthotics, braces, prosthetics, face masks and other medical equipment that comes in contact with skin often slip, become contaminated or use materials that smell over time. Such materials do not work well with concave surfaces or in situations that need low profile, non-tacky gripping. NanoGriptech says that Setex offers an alternative in this area.

The technology can also be used for surgical tool grip. The current challenge is surgical tool design is to create tools that improve grip without tacky contaminants or adding profile that decreases touch-sensitivity and NanoGripTech says this technology enables surgical tool providers to create sterile tool grips improve gripping performance, without residue or bulkiness.

NanoGriptech was founded by Metin Sitti, a professor of mechanical engineering at Carnegie Mellon university in the US, who worked for nearly a decade to understand and synthesise biologically inspired micro/nanostructured adhesives.

“Much like Velcro or Kevlar, we believe Setex will disrupt markets because of its many commercial applications. Setex is residue-free, strong and reusable,” says Roi Ben Itzhak, NanoGriptech CFO and vice president of business development. “There are other gecko-inspired materials in labs around the world, but, unlike Setex, they have all have weak peel strengths and are prohibitively expensive to manufacture.”

Setex’s glue-free fibres mimic the adhesive qualities of gecko foot hair. Intermolecular forces found at the tips of the hairs enable geckos to walk across ceilings. Like a gecko’s foot, Setex can be applied to a variety of surfaces and lifted repeatedly. The synthetic fibres are strong – several square inches of Setex will support hundreds of pounds. NanoGriptech researchers can customise their manufacturing techniques at the microscale level to produce materials that are modified for different applications, such as enhancing a robot’s ability to pick up a part or improving the fit of prosthetic limbs on skin.