Nature News reports on the work of Mark Sims, exobiologist. He's developed a toaster-sized device to go on an upcoming ESA mission to Mars, intended to look for life -- using tiny patches of sticky plastic film.

The Specific Molecular Identification of Life Experiment (SMILE -- and someone needs to start slapping people who push for acronyms like this) will look for biomarkers -- molecules that are strongly indicative of life, from complex hydrocarbons to amino acids. The plastic film patches have molecule-size cavities designed to match specific biomarkers. This is a common technique with Earthly sensors, but the base material is usually biological in origin; by using polymers, researchers can avoid contamination of the sample, and of the Martian environment.

The SMILE biosensors may end up being used on Earth, too. As they are more resilient than biological material-based patches, they can be used in a wider array of applications. Scientists looking for extremophiles in deep sea vents or ice, forensic specialists trying to keep from contaminating samples, and security specialists needing inexpensive, rugged bioweapon sensors have all shown interest in the technology.