Phone calls and text messages reach users wherever they are because each phone has a unique identifying number that sets a user apart from others on the network. Researchers at the Georgia Institute of Technology are using a similar principle to track cells being sorted on microfluidic chips. The technique uses a simple circuit pattern with only three electrodes to assign a unique seven-bit digital identification number to each cell passing through the channels on the microfluidic chip. The new technique also captures information about the sizes of the cells, and how fast they are moving. That identification and information could allow automated counting and analysis of the cells being sorted. The next step in the research will be to combine the electronic sensor with a microfluidic chip able to actively sort cells. Beyond cancer cells, bacteria and viruses, such a system could also sort and analyze inorganic particles.