Arunachalam Murgamarham: The PadMan.

A school dropout from a poor family in southern India has revolutionised menstrual health for rural women in developing countries by inventing a simple machine they can use to make cheap sanitary pads.

Arunachalam Muruganantham's invention came at great personal cost - he nearly lost his family, his money and his place in society. But he kept his sense of humour.

"It all started with my wife," he says. In 1998 he was newly married and his world revolved around his wife, Shanthi, and his widowed mother. One day he saw Shanthi was hiding something from him. He was shocked to discover what it was - rags, "nasty cloths" which she used during menstruation.

"I will be honest," says Muruganantham. "I would not even use it to clean my scooter." When he asked her why she didn't use sanitary pads, she pointed out that if she bought them for the women in the family, she wouldn't be able to afford to buy milk or run the household.

Wanting to impress his young wife, Muruganantham went into town to buy her a sanitary pad. It was handed to him hurriedly, as if it were contraband. He weighed it in his hand and wondered why 10g (less than 0.5oz) of cotton, which at the time cost 10 paise (£0.001), should sell for 4 rupees (£0.04) - 40 times the price. He decided he could make them cheaper himself.

He fashioned a sanitary pad out of cotton and gave it to Shanthi, demanding immediate feedback. She said he'd have to wait for some time - only then did he realise that periods were monthly. "I can't wait a month for each feedback, it'll take two decades!" He needed more volunteers.

When Muruganantham looked into it further, he discovered that hardly any women in the surrounding villages used sanitary pads - fewer than one in 10. His findings were echoed by a 2011 survey by AC Nielsen, commissioned by the Indian government, which found that only 12% of women across India use sanitary pads.

Muruganantham says that in rural areas, the take-up is far less than that. He was shocked to learn that women don't just use old rags, but other unhygienic substances such as sand, sawdust, leaves and even ash.

Women who do use cloths are often too embarrassed to dry them in the sun, which means they don't get disinfected. Approximately 70% of all reproductive diseases in India are caused by poor menstrual hygiene - it can also affect maternal mortality.

Finding volunteers to test his products was no mean feat. His sisters refused, so he had the idea of approaching female students at his local medical college. "But how can a workshop worker approach a medical college girl?" Muruganantham says. "Not even college boys can go near these girls!"

He managed to convince 20 students to try out his pads - but it still didn't quite work out. On the day he came to collect their feedback sheets he caught three of the girls industriously filling them all in. These results obviously could not be relied on. It was then that he decided to test the products on himself. "I became the man who wore a sanitary pad," he says.

He created a "uterus" from a football bladder by punching a couple of holes in it, and filling it with goat's blood. A former classmate, a butcher, would ring his bicycle bell outside the house whenever he was going to kill a goat. Muruganantham would collect the blood and mix in an additive he got from another friend at a blood bank to prevent it clotting too quickly - but it didn't stop the smell.

He walked, cycled and ran with the football bladder under his traditional clothes, constantly pumping blood out to test his sanitary pad's absorption rates. Everyone thought he'd gone mad.

He used to wash his bloodied clothes at a public well and the whole village concluded he had a sexual disease. Friends crossed the road to avoid him. "I had become a pervert," he says. At the same time, his wife got fed up - and left. "So you see God's sense of humour," he says in the documentary Menstrual Man by Amit Virmani. "I'd started the research for my wife and after 18 months she left me!"

Then he had another brainwave - he would study used sanitary pads: surely this would reveal everything. This idea posed an even greater risk in such a superstitious community. "Even if I ask for a hair from a lady, she would suspect I am doing some black magic on her to mesmerise her," he says.

He supplied his group of medical students with sanitary pads and collected them afterwards. He laid his haul out in the back yard to study, only for his mother to stumble across the grisly scene one afternoon. It was the final straw. She cried, put her sari on the ground, put her belongings into it, and left. "It was a problem for me," he says. "I had to cook my own food."

Worse was to come. The villagers became convinced he was possessed by evil spirits, and were about to chain him upside down to a tree to be "healed" by the local soothsayer. He only narrowly avoided this treatment by agreeing to leave the village. It was a terrible price to pay. "My wife gone, my mum gone, ostracised by my village" he says. "I was left all alone in life."

Still, he carried on. The biggest mystery was what successful sanitary pads were made of. He had sent some off for laboratory analysis and reports came back that it was cotton, but his own cotton creations did not work. It was something he could only ask the multinational companies who produced sanitary products - but how? "It's like knocking on the door of Coke and saying, 'Can I ask you how your cola is manufactured?'"

Muruganantham wrote to the big manufacturing companies with the help of a college professor, whom he repaid by doing domestic work - he didn't speak much English at the time. He also spent almost 7,000 rupees (£70) on telephone calls - money he didn't have. "When I got through, they asked me what kind of plant I had," he says. "I didn't really understand what they meant."

In the end, he said he was a textile mill owner in Coimbatore who was thinking of moving into the business, and requested some samples. A few weeks later, mysterious hard boards appeared in the mail - cellulose, from the bark of a tree. It had taken two years and three months to discover what sanitary pads are made of, but there was a snag - the machine required to break this material down and turn it into pads cost many thousands of dollars. He would have to design his own.

Four-and-a-half years later, he succeeded in creating a low-cost method for the production of sanitary towels. The process involves four simple steps. First, a machine similar to a kitchen grinder breaks down the hard cellulose into fluffy material, which is packed into rectangular cakes with another machine.

The cakes are then wrapped in non-woven cloth and disinfected in an ultraviolet treatment unit. The whole process can be learned in an hour.

Muruganantham's goal was to create user-friendly technology. The mission was not just to increase the use of sanitary pads, but also to create jobs for rural women - women like his mother. Following her husband's death in a road accident, Muruganantham's mother had had to sell everything she owned and get a job as a farm labourer, but earning $1 a day wasn't enough to support four children. That's why, at the age of 14, Muruganantham had left school to find work.

The machines are kept deliberately simple and skeletal so that they can be maintained by the women themselves. "It looks like the Wright brothers' first flight," he says. The first model was mostly made of wood, and when he showed it to the Indian Institute of Technology, IIT, in Madras, scientists were sceptical - how was this man going to compete against multinationals?

But Muruganantham had confidence. As the son of a handloom worker, he had seen his father survive with a simple wooden handloom, despite 446 fully mechanised mills in the city. That gave him the courage to take on the big companies with his small machine made of wood - besides, his aim was not really to compete. "We are creating a new market, we are paving the way for them," he says.

Unbeknown to him, the IIT entered his machine in a competition for a national innovation award. Out of 943 entries, it came first. He was given the award by the then President of India, Pratibha Patil - quite an achievement for a school dropout. Suddenly he was in the limelight.

"It was instant glory, media flashing in my face, everything" he says. "The irony is, after five-and-a-half years I get a call on my mobile - the voice huskily says: Remember me?"

It was his wife, Shanthi. She was not entirely surprised by her husband's success. "Every time he comes to know something new, he wants to know everything about it," she says. "And then he wants to do something about it that nobody else has done before."

However, this kind of ambition was not easy to live with. Not only was she shocked by his interest in such a matter, but it took up all of his time and money - at the time, they hardly had enough money to eat properly. And her troubles were compounded by gossip.

"The hardest thing was when the villagers started talking and treating us really badly," she says. "There were rumours that he was having affairs with other women, and that was why he was doing such things." She decided to go back home to live with her mother.

After Shanthi, eventually Muruganantham's own mother and the rest of the villagers - who had all condemned, criticised and ostracised him - came round too.

Muruganantham seemed set for fame and fortune, but he was not interested in profit. "Imagine, I got patent rights to the only machine in the world to make low-cost sanitary napkins - a hot-cake product," he says. "Anyone with an MBA would immediately accumulate the maximum money. But I did not want to. Why? Because from childhood I know no human being died because of poverty - everything happens because of ignorance."

He believes that big business is parasitic, like a mosquito, whereas he prefers the lighter touch, like that of a butterfly. "A butterfly can suck honey from the flower without damaging it," he says.

There are still many taboos around menstruation in India. Women can't visit temples or public places, they're not allowed to cook or touch the water supply - essentially they are considered untouchable.

It took Muruganantham 18 months to build 250 machines, which he took out to the poorest and most underdeveloped states in Northern India - the so-called BIMARU or "sick" states of Bihar, Madhya Pradesh, Rajasthan, and Uttar Pradesh. Here, women often have to walk for miles to fetch water, something they can't do when they are menstruating - so families suffer.

"My inner conscience said if I can crack it in Bihar, a very tough nut to crack, I can make it anywhere," says Muruganantham.

It was hard even to broach the subject in such a conservative society. "To speak to rural women, we need permission from the husband or father," he says. "We can only talk to them through a blanket."

There are also myths and fears surrounding the use of sanitary pads - that women who use them will go blind, for example, or will never get married. But slowly, village by village, there was cautious acceptance and over time the machines spread to 1,300 villages in 23 states.

In each case, it's the women who produce the sanitary pads who sell them directly to the customer. Shops are usually run by men, which can put women off. And when customers get them from women they know, they can also acquire important information on how to use them. Purchasers may not even need any money - many women barter for onions and potatoes.

While getting the message out to new areas of the country is still difficult, Muruganantham is sceptical about the effectiveness of TV advertising. "You always have a girl in white jeans, jumping over a wall," he says. "They never talk about hygiene."

Most of Muruganantham's clients are NGOs and women's self-help groups. A manual machine costs around 75,000 Indian rupees (£723) - a semi-automated machine costs more. Each machine converts 3,000 women to pad usage, and provides employment for 10. They can produce 200-250 pads a day which sell for an average of about 2.5 rupees (£0.025) each.

Women choose their own brand-name for their range of sanitary pads, so there is no over-arching brand - it is "by the women, for the women, and to the women".

Muruganantham also works with schools - 23% of girls drop out of education once they start menstruating. Now school girls make their own pads. "Why wait till they are women? Why not empower girls?"

The Indian government recently announced it would distribute subsidised sanitary products to poorer women. It was a blow for Muruganantham that it did not choose to work with him, but he now has his eyes on the wider world. "My aim was to create one million jobs for poor women - but why not 10 million jobs worldwide?" he asks. He is expanding to 106 countries across the globe, including Kenya, Nigeria, Mauritius, the Philippines, and Bangladesh.

"Our success is entirely down to word-of-mouth publicity," he says. "Because this is a problem all developing nations face."

Muruganantham now lives with his family in a modest apartment. He owns a jeep, "a rugged car that will take me to hillsides, jungles, forest", but has no desire to accumulate possessions. "I have accumulated no money but I accumulate a lot of happiness," he says. "If you get rich, you have an apartment with an extra bedroom - and then you die."

He prefers to spend his time talking to university and college students. He's an engaging and funny speaker, despite his idiosyncratic English. He says he is not working brain to brain but heart to heart.

"Luckily I'm not educated," he tells students. "If you act like an illiterate man, your learning will never stop... Being uneducated, you have no fear of the future."

His wife Shanthi agrees with him on this point. "If he had completed his education, he would be like any other guy, who works for someone else, who gets a daily wage," she says. "But because he did not complete school, he had the courage to come out to start a business of his own. Now he's employing other people."

Shanthi and Muruganantham are now a tight unit. "My wife, the business - it is not a separate thing, it is mixed up with our life," he says.

When a girl reaches puberty in their village, there is a ceremony - traditionally it meant that they were ready to marry. Shanthi always brings a sanitary pad as a gift and explains how to use it.

"Initially I used to be very shy when talking to people about it," she says. "But after all this time, people have started to open up. Now they come and talk to me, they ask questions and they also get sanitary napkins to try them. They have all changed a lot in the village."

Muruganantham says she does a wonderful job.

He was once asked whether receiving the award from the Indian president was the happiest moment of his life. He said no - his proudest moment came after he installed a machine in a remote village in Uttarakhand, in the foothills of the Himalayas, where for many generations nobody had earned enough to allow children to go to school.

A year later, he received a call from a woman in the village to say that her daughter had started school. "Where Nehru failed," he says, "one machine succeeded."