"Cancer cells have a high requirement for folic acid as it is necessary for their metabolism, so the cells have 500 times more folate receptors compared with a healthy cell, explains Castillo-León. The receptors are like antennas on the surface of the cell membrane that seek out folic acid. The cancer cells interact with the electrochemical platform, resulting in a decrease in the current being measured. The sensor allows the detection of cancer cells at a concentration as low as 250 cells per millilitre."