Lab-on-a-chip. This lab-on-a-chip is designed to detect T-cells (lymphocytes) that express the protein CD4. HIV, the virus that causes AIDS, attacks cells containing CD4 and the onset of full-blown AIDS can be measured by a dramatic reduction in CD4 carrying T-cells. The chip (centre) contains thousands of microscopic silicon pillars coated with CD4 antibodies. When blood from a syringe (upper right) is injected into the chip, the CD4 cells are isolated from the blood, which can then be counted under a light microscope. This lab-on-a-chip, created by biomedical engineer Mehmet Toner could one day be used as an accurate, reliable and cheap method to monitor the blood of HIV patients. Photographed in 2009.