5 April 2020

Amin Doostmohammadi publishes in Nature Physics


In a study published in Nature Physics, NBIA Assistant Professor Amin Doostmohammadi together with colleagues in Britain and the U.S. have used “living liquid crystals” to focus bacteria into jets. Bacteria are microscopic engines that convert chemical energy to motion. They form a significant proportion of the total biomass on earth, exceeding that of all plants and animals combined. This raises the possibility of exploiting them to perform useful work for us: to move particles around and deliver small sized cargoes. The challenge is that in nature most bacterial colonies exhibit chaotic and disorganized patterns of motion and they need to be organized to move along well-defined tracks to be useful as machines.

Liquid crystals are rod-like molecules that can be easily organized into complicated patterns: this is the physics underlying liquid crystal displays (LCDs) for televisions, monitors and mobile phones. Amin Doostmohammadi and co-workers show that combining living bacteria with a smart structured liquid crystal can cause a bacteria colony to condense into well-defined tracks. Strikingly, within the pre-designed lanes of liquid crystals bacteria flow like a jet of fluid that pumps itself.

Experiments reported in their Nature Physics paper (https://www.nature.com/articles/s41567-020-0793-0) show that microscopic cargoes introduced into the lanes can be transported uni-directionally by the bacterial jets. This ability of a liquid crystalline medium to streamline the chaotic movements of swimming bacteria into jets that can carry cargo along a pre-designed trajectory opens the door for potential applications in cell sorting, microscale delivery and soft micro-robotics.