Harvard researchers have developed a device for testing water quality and identifying pathogens that can be made simply from paper, ink and sunlight. It could help developing countries access the latest lab techniques inexpensively.

The device uses pores naturally present in paper to carry liquids in a way similar to standard microfluidic chips. A pattern is placed over photoresist-soaked paper. Where exposed to sunlight, the resist becomes impermeable, leaving a network of channels.