How water bottles create cheap lighting...
The BBC's Kate McGeown reports from Manila.
Alfredo Moser´s invention is lighting up the world. In 2002, the Brazilian mechanic had a light-bulb moment and came up with a way of illuminating his house during the day without electricity -using nothing more than plastic bottles filled with water and a tiny bit of bleach.
So how does it work? Simple refraction of sunlight, explains Moser, as he fills an empty two-litre plastic bottle.
"Add two capfuls of bleach to protect the water so it doesn´t turn green (with algae), The cleaner the bottle, the better", he adds.
Wrapping his face in a cloth he makes a hole in a roof tile with a drill. Then, from the bottom upwards, he pushes the bottle into the newly-made hole.
"You fix the bottle in with polyester resin. Even when it rains, the roof never leaks -not one drop."
This simple initiative in the Philippines is bringing a bit of brightness into the lives of the country´s poorest people.
In short, the project is called "Litre of Light" and the technology is just a plastic bottle filled with water.
It´s an environmentally-friendly alternative to an electric light bulb and it´s virtually free.
The house in London that is 3D illusion
An artist has created an apparently gravity-defying house in a street in east London.
Visitors to the installation are able to climb at what appears to be daring heights and angles.
Tim Muffett reports.
UN considers ethics of "killer robots"
A report raising questions about the ethical use of so-called "killer robots" has been debated at he UN Human Rights Council in Geneva.
The robots are machines programmed to kill people or destroy targets. Unlike drones, they operate autonomously on the battefield.
The UN rapporteur behind the report, Christof Heyns, said he was calling for a halt to their use until the ethical issues could be worked out.
Imogen Foulkes reports from Geneva.
Making robots to interacts with humans
Would you be comfortable being surrounded by robots?
One British manufacturing firm is trying to make robots that share more human characteristics, to make interaction with them more natural and intuitive than ever before.
Engineered Arts in Cornwall is in the vanguard of this area of research, which aims to make robots' facial expressions, body language and way of moving more recognisable to real people.
Founder Will Jackson gave a tour of his robot factory to the BBC, and explained how he and his team of a dozen people are looking to expand the frontiers of robot technology.
Video journalist: Dougal Shaw
Up Next is a new series of video features for the BBC News website which examines the new developments that could affect all of our lives in the future.
Is this interactive avatar the face of the future?
A virtual "talking head" which can express a range of human emotions and could be used as a digital personal assistant has been developed by researcher in Cambridge.
According to its designers, Zoe is the most expressive controllable avatar ever created and could be used on mobile phones or tablets.
The result of several days filming with an actress, the face can display emotions such as happiness, anger and fear and changes its voice to suit the user´s preference.
Rory Cellan-Jones went to meet the team behind Zoe and find out how they make it work.
Combination of software and hardware results in a car that drives itself.
Anechoid chamber: The room that "sucks out" sound
What is it like to spend time in one of the quietest rooms in the world?
For The Why Factor on the BBC World Service, the BBC's Mike Williams set out to investigate what role silence plays in our increasingly noisy lives.
As part of his research he went into an anechoic chamber at the University College of London to get as close as possible to experiencing what true silence sounds like.
Although tiny amounts of sound leak into the room the levels are so quiet that they are not audible to the human ear.