The shape of condoms to come

But getting people to use condoms correctly is still a big challenge, according to William Yarber, senior director of the Rural Center for AIDS/STD Prevention at Indiana University, Bloomington.

"From our research, many want to use condoms but have had negative experiences with condom use, believe the 'bad reputation' of condoms, or do not know much about correct condom use and how to use condoms while experiencing pleasure," he says.

There are a variety of reasons for why people are resistant to using condoms – religious grounds, poor sexual education and a dislike of the way they feel. Condom breakages or slippages are relatively uncommon, but do occur – some studies estimate they occur in between 1% and 5% of cases – and this can also impact confidence and whether people use them.

It has led researchers to search for ways of improving the humble condom with innovative materials and technologies in the hope that it might enable more people to use them.

One promising idea for stronger condoms uses graphene – an ultrathin single layer of carbon atoms that was first identified by Nobel Prize winning scientists at the University of Manchester, UK, in 2004. Aravind Vijayaraghavan, a materials scientist at the National Graphene Institute at the University of Manchester, believes "the world's thinnest, lightest, strongest and best heat conductive material" could be ideal to improve the properties of condoms.

His team was given a grant by the Bill and Melinda Gates Foundation in 2013 as part of a campaign to develop innovative condom designs. But graphene cannot be made into any standalone objects on its own, so Vijayaraghavan's team are combining graphene with both latex and polyurethane.

"Graphene is a nano-scale material, which is just one atom thick and few micrometres wide," he says. "But at that small scale, it is the strongest material on the planet. The challenge is to transfer that strength from nano-scale to macro-scale, at which we use real world objects. We do this by combining the strong graphene particles with a weak polymer, like natural rubber latex or polyurethane. The graphene then imparts its strength to the weak polymer to make it stronger by reinforcing it at the nano-scale."

This combination can increase the strength of a thin polymer film by 60% or allow condoms to be made 20% thinner while retaining their current strength, Vijayaraghavan adds. Although graphene condoms have yet to be available, the team are currently working on commercialising their innovative, strengthened rubber.

Another group working to make the material used in condoms thinner and stronger are based at the University of Queensland, Australia. Here they are developing condoms that combine latex with fibres from the Australian native spinifex grass.

Spinifex resin has long been used as an adhesive by the indigenous communities in Australia such as when making stone tipped tools and weapons. The researchers found they were able to reinforce latex with nanocellulose extracted from pulped grass. The resulting latex films were up to 17% stronger and could be made thinner. The researchers say they were able to produce a condom that could withstand 20% more pressure in a burst test and could be inflated to 40% larger compared to commercial latex condoms.

Nasim Amiralian, a materials engineer at the University of Queensland who is one of those leading the project, says the team are now working with condom manufacturers in an attempt to optimise the formulations and processing methods. Their hope is that they can make condoms that are stronger but also perhaps up to 30% thinner than current condoms, which might improve uptake by making them feel less noticeable when being worn.

The material could also find other uses, such as to produce stronger but more sensitive gloves for surgeons.

But while latex is currently the most common material used in condoms, many people find them uncomfortable to use and often require lubricants. Latex is also relatively expensive, which can be an additional barrier to condom use.

About 4.3% of the world's population also suffer from latex allergy, making the most common type of condoms unusable for millions of people. While alternatives such as polyurethane or natural membrane condoms are available, they have drawbacks. Polyurethane condoms break a lot more easily than latex condoms, while natural membrane condoms contain small pores that do not block the passage of STD pathogens including hepatitis B and HIV.

Another group of Australian scientists, however, want to replace latex with a new material called "tough hydrogel". Most hydrogels – a polymer network swollen by water – tend to be soft and squidgy, but those being worked on by researchers at Swinburne University of Technology and the University of Wollongong in Australia are strong and stretchy like rubber.

The team have established a spin-out company called Eudaemon that is trying to build on the initial research into the "GelDoms". As they contain no latex, they can avoid the allergy issues that are associated with traditional condoms, but the team say their hydrogels can also be designed to feel more like human skin, and so have a more natural feel.

As the hydrogel contains water, they are also self-lubricating, or can be created with anti-STD medication built into their structure that is released during use.

Ensuring condoms can be used without additional lubrication is another challenge that scientists have turned their attention to. One group of researchers at Boston University in the US have developed a coating that can be applied to condoms that allows them to become self-lubricating.

The researchers founded a spin-off company, HydroGlyde Coatings, for the innovation. Stacy Chin, chief executive and co-founder of the start-up, says the self-lubricating condoms can withstand at least 1,000 thrusts, compared to regular condoms' only around 600 thrusts.

Most lubricants used on latex condoms tend to be sticky, repel water and diminish during use. The researchers at Boston University, however, found they could bond a thin layer of hydrophilic – or water-loving – polymers to the surface of latex. When the polymers come into contact with water they become slippery to touch. This means they could use moisture from bodily fluids to remain slippery and reduce friction throughout use.

"Lubricants are messing with condoms as they are hydro-unfriendly. Our coating can stay on the latex condoms during the intercourse to offer continuous lubrications. It solves one of the biggest problems [in using condoms]," Chin says.

The coating was found to reduce friction by 53% in a small 33-person survey compared to a unlubricated latex and performed similarly to commercially available lubricants. In the small-scale blind touch tests, 70% of participants preferred condoms with the new coating to that with personal lubricant.

As the product is currently going through a process of commercialisation, Chin says she cannot reveal more details about how long it might be before the new self-lubricating condoms are available.

Fit is another issue that often can be a problem, and one condom maker in the US is selling custom-fit condoms in 60 sizes. One study from the Indiana University in 2014 found that the erect length of penises of 1,661 sexually active men in the US ranged from 4cm-26cm while their circumference ranged from 3cm to 19cm. The average length of a male condom is 18cm.

In response, the Global Protection Corporation is offering condoms that come in 10 different lengths and nine circumferences. Cynthia Graham, a professor in sexual and reproductive health at the University of Southampton and a researcher at the condom team at The Kinsey Institute at Indiana University, has also been assessing whether new ways of putting on condoms might make them easier to use. They have been testing a new type of condom that uses a built in applicator that allows the condom to be put on without it being touched.

It comes with a wrapper that features a pull tab for an easy grip and unsealing. The aim is to prevent potential damage of a condom in a conventional foil condom wrapper. It uses a pair of unrolling strips that disengage when it is fully unrolled – an attempt to ensure they it is fitted properly before use. But the device has yet to be used in clinical trials due to a lack of funding.

And there are other more fundamental issues that stand in the way of condom use.

"It is pretty common for people not to use condoms – they use them to prevent pregnancy instead of STIs. What's worse is that a lot of young people thought most of them are treatable, so they are not concerned about them," says Graham.

Even with stronger, thinner and more comfortable condoms, it is clear that there is a lot that could be achieved with some more education too.