For decades Santosh Ostwal obsessed over an obscure problem: how to make it easier for Indian farmers to water their crops.

As a kid in 1981, Ostwal would watch his one-legged grandfather make the one-mile trek out to his fields to irrigate his land. It was arduous and repetitive; access to electricity and water was sporadic. Now an engineer, Ostwal has finally solved his grandfather's problem with a phone-controlled water pump-starter called the Nano Ganesh. It's an elegant example of how mobile phones are being used in the developing world in incredibly innovative ways.

Here's how the Nano Ganesh works. A farmer purchases the device for between $12 and $268, depending on the model. The device is then connected both to a mobile phone and the electric water pump. Once it's set up, the farmer just needs to call that phone and enter a code to get it going. No cell service? No problem. Ostwal also made a remote control. He claims the water, electricity and time savings can cover the cost of the device in 11 days. But creating the device was far from easy, Ostwal told The Economist recently:

My wife is an electronics engineer. She used to assemble all the things in our bedroom. I used to play the things all over the day on the farm. She used to work during night. I used to come home at midnight or 2 or even 3 o'clock. She would ask me, 'Tomorrow morning which tool do you want to take away with you?' In my sleep, I would hand over some modifications to her and tell her to make that prototype in time for my early morning visit at 6. And my wife did it at 3 o' clock in the morning with two kids beside her - one is of 3 years and the other of one year.



In 2009, the invention won the top prize in a global mobile innovation contest run by Nokia.