Researchers at MIT and the Max Planck Institute have developed a method for quick, on-site E. coli detection in food. While current food safety testing either requires days to complete or expensive equipment, this new method, paired with a smartphone and QR code, will make testing inexpensive and portable. The new detection process uses Janus emulsions, droplets consisting of two hemispheres of different densities. In water, the less dense, hydrocarbon hemisphere sits above the denser hemisphere