It takes just a peek at the online store Condomania to appreciate the variety of condoms out there.
Flavors like island punch, banana split and bubble gum. Vibrating condom rings with batteries that last up to 20 minutes. Glow-in-the-dark condoms promising "30 minutes of glowing fun."
And under the category "Celebrity Condoms," there is the "Obama Condoms Stimulus Package," each condom embossed with an image of the president giving two thumbs up.
But even if that presidential seal of approval were real, it would not overcome a chronic and serious public health obstacle: Most men do not like condoms.
Now an influential player in global health, the Bill and Melinda Gates Foundation, is getting into the game. The foundation just finished collecting applications for what it calls a Grand Challenge: to develop "anext-generation condom that significantly preserves or enhances pleasure."
The goal is to address two significant problems: unintended pregnancies and sexually transmitted diseases like AIDS. Condoms cheaply and effectively prevent both, but around the world only 5 percent of men wear them and there are 2.5 million new H.I.V. infections a year. To stem that tide, health experts say, the number of men regularly using condoms needs to double.
"Decreased sexual pleasure is typically the predominant reason for not using them," said Stephen Ward, a program officer for the Gates Foundation. "Can we actually make them more desirable? That's what we're shooting for."
More than 500 applications poured into the Gates contest, which will award winners $100,000 this fall, and up to $1 million subsequently. And in a first for a Gates challenge, Mr. Ward said, people sent samples.
"Boxes of condoms, condom accessories, condom cases that look like something else so women can be very discreet while carrying them," he said. "We received a completely stocked carrying case with condoms, lubricant and breath mints."
Contestants have been advised not to discuss their applications publicly, meaning that the creator of a YouTube video who pitched Mr. Gates a condom applied via slingshot is probably not a serious contender.
But condom experts - some of whom have studied the subject for years - have ideas of what might work and what decidedly won't.
"I don't think we've seen the condom that knocks the socks off for everybody," said Ron Frezieres, vice present of research and evaluation at the California Family Health Council, a longtime tester of condoms for industry, government and nonprofit organizations.
"Guys would like it if they, first of all, don't believe they're wearing it," Mr. Frezieres continued. "And second of all, it's got to be a little better than what they're used to. We still have to find that perfect bullet."
Perfect may not be the enemy of the good in this case, but it is awfully hard to pin down.
"When I saw that Gates announcement," said Jeff Spieler, a senior technical adviser on population and reproductive health at the United States Agency for International Development, "I wrote and said, 'It's great that you're doing this, but I've been there before, and I hope you're going to surface something that I couldn't surface.'
"This has been my passion for years and years," Mr. Spieler added. "I started thinking, 'Gosh, if we could develop a condom that made sex better with the condom than without … .'If at least it didn't take sexual pleasure away, it would not be like taking a shower with a raincoat on."
At first, he recalled, his bosses said: "Hey, Jeff, be careful. We don't want Congress to come beating down on this because Jeff Spieler's trying to make sex better."
Several manufacturers have worked on more appealing condoms. Some models, like Pleasure Plus and Twisted Pleasure, designed by an Indian surgeon, Alla Venkata Krishna Reddy, whom Mr. Spieler called the "Leonardo da Vinci of condoms," addressed complaints of tightness and friction. They are roomy, ballooning, "sort of like the swirl of a Dairy Queen ice cream," Mr. Spieler said. The movement of extra material is intended to be stimulating.
Another design, the eZ-On condom, was aimed at the "donning problem." Made of polyurethane, not latex, it was baggy, "gathered up inside what I call a tutu," Mr. Frezieres said. "It was not directional, so you could pull it down from either side" - or as Mr. Spieler put it, "like slipping your foot into an open sock."
But only some men appreciate that feature. It turns out that condoms are subject to a wide array of likes and dislikes.
"Some men want it absolutely clear so if they look down they can think they don't have anything on," Mr. Frezieres said. "Others want to make it red and vibrating, like a neon sign."
Mr. Frezieres and his colleague Terri L. Walsh conducted studies involving condoms with lubricants that create a heating sensation. "Some people said, 'This is burning me,'" he said, but others reported a mild, pleasant feeling or even more intense orgasms. On the other hand, as Ms. Walsh pointed out, a stimulating condom could make matters worse for men with premature ejaculation, so for them, the question is, "How much more exciting do you want to make a condom?"
Another testing quandary, Mr. Spieler said, is that "you can't compare one sex act to another sex act. You can come into a sex act having just argued and having makeup sex. You could have three days of bad sex, so you don't rate the condom you're testing very well."
That has not stopped innovation in the condom industry. There are vibrating condom rings like the Durex Play – Ring of Bliss, said Bidia Deperthes, a senior H.I.V. technical adviser for the United Nations Population Fund. (Mr. Spieler calls her "the condom czarina.") Some men invariably gripe about the battery life: "Bidia, 20 minutes, it's not that long." Her response: "Guys, give me a break. Fifteen minutes is already flattering you."
Ms. Deperthes, whose office features a wall of condoms, has versions packaged like lollipops, miniature chocolate milk cartons and cellophane-wrapped taffy.
And what's that pinned to her silk blouse? A brooch of batik fabric. But on the flip side of the pin is, yes, a condom. Talk about wearable art.
One unsuccessful innovation was the Hat condom, resembling a little shower cap, designed, said Mr. Frezieres, "to fit just over the tip," to "provide maximum sensation." Alas, "in clinical testing, couples experienced difficulty keeping the Hat condom from popping off," he said.
Another idea was the spray-on condom, applying liquid latex to create a condom shaped for the man using it. "Great concept," Mr. Frezieres said. But it did not have a tip to collect fluid, and "we were like, how do you get it off afterward?"
One promising design, already available in some parts of the world, is the Pronto 4:Secs condom, its box decorated with racy Dick Tracyesque cartoons. 4:Secs, its name both a pun and the time it is supposed to take to put on, is a condom in a plastic applicator resembling a life preserver.
"This is really cool," said Ms. Deperthes, demonstrating how the applicator splits apart to allow the condom to be put on right-side up.
And perhaps the most innovative new American-made product is the Origami condom, still in clinical trials. Its inventor, Danny Resnic, said he was motivated by his own experience when "a latex condom broke and I wound up with an H.I.V. diagnosis."
Years of experimenting led him to devise a condom with accordionlike pleats, loose to allow movement inside. Made of silicone, which is meant to feel more like skin, it "goes on in less than a second," he said, and "there's no wrong way to put it on."
Besides male condoms, which Origami calls "external condoms," the company has a female version (an "internal condom"), and the first condoms for anal sex and oral sex, Mr. Resnic said.
The Gates Foundation contest also welcomed designs for female condoms, but female condoms have historically been less popular.
While some men prefer the experience, and some women feel it affords them greater ability to protect themselves, it is much more expensive and needs to be positioned correctly to avoid getting pushed in or shifted to one side.
One idea to make it more attractive, Mr. Frezieres said, is to attach the female condom to a "string-bikini-looking panty, like a thong."
In the developing world, condoms raise other issues. In some cultures, men are so resistant that women must engage in delicate "condom negotiation." And women who carry condoms might be assumed to be prostitutes.
Ms. Deperthes and Franck DeRose, executive director of the nonprofit Condom Project, use songs and dances about condoms to try to make them seem fun, and give women ways to carry condoms discreetly, including containers that look like breath mint boxes.
Ms. Deperthes also wants more options; for example, she noted that the two standard sizes were too big for some men, so smaller sizes should be included in packages donated to developing countries.
And she wants more variety.
"I told the condom working group at U.S.A.I.D., 'Guys, you are boring, boring, boring,'" Ms. Deperthes said. The standard condom that countries receive "doesn't smell good - it smells like rubber."
Told that 18 choices are offered, she said better marketing was needed, since most countries choose the same plain-vanilla type. Ms. Deperthes is developing a "chocolate box," displaying different condoms like truffles, to send to foreign health ministers. Indeed, given the wide array of personal and cultural differences, she and others said, the value of the Gates Foundation contest may be in finding several types of condoms - perhaps of new materials - and in helping them be produced inexpensively enough for the developing world.
As Mr. DeRose put it: "Sometimes you want to wear boots, sometimes you want to wear flip-flops."
Testing Condoms: Someone Has to Do It
As guinea pigs in scientific clinical trials, Amy and Max H. take their commitment seriously. They perform the required tests of each product at least several times. They fill out the required forms. After all, they consider it a big responsibility: testing condoms for the California Family Health Council.
"We call it sex for science," said Amy, who, like Max, is 26. (They agreed to speak only if their full names were withheld.)
They are so diligent that they fill out the forms right after testing a condom. "If I fall asleep and I wake up in the morning and do it, I'm not going to be able to remember the answer to any of the questions," Max said.
The questions couples are asked are detailed. They include "what they like, didn't like, did it break, did it flip, did it hurt, how was sex, how was orgasm," said Ron Frezieres, vice president of research and evaluation for the council, which recruits many of its study participants through Craigslist.
Max has not been a great fan of condoms. For about 18 months he and Amy, who live in Los Angeles and have been together for eight years, used condoms for birth control, and "God, it was stressful," he said.
"While you're naked and you're with another naked person and you're in bed, and you're not 100 percent focused on, like, how I put this on properly. It's really difficult. And it's a situation where you often don't probably find yourself with two hands free."
Also, he said, "if surprise sex happens and you're not near your condom drawer, you have to go get your condom."
Amy had fewer quibbles. "Yes, sometimes, it was like the worst thing to ever happen on the planet," she said. "But even if you're, like, 'I want you right now,'it can be almost like a fun pause because you're forced to let it linger for a little bit longer."
When they started testing condoms for the council, neither was overwhelmingly impressed with the new versions, which were mostly standard-design condoms made of materials besides latex.
They had some differences of opinion. Amy liked polyurethane, for example, because "it kind of heats up a little bit more," she said. But Max said: "They felt very plastic-y. Latex stretches, and the other materials didn't so much."
But they were unanimous in their antipathy to the female condom. As Max put it: "We both found the female condom to be aggressively unsexy. It didn't really seem to make much difference in terms of feeling, but visually we were like, 'Oh, man, we should just stop.'"