A Label-free CMOS DNA Microarray based on Charge Sensing

The first label-free CMOS DNA polymerization sensor is reported. The 5-by-5 sensor array measures the charge induced on an electrode from a DNA fragment undergoing polymerization. Importantly, no post-processing is required as passivated top-metal electrodes are used. The measured limit of detection (with enzymatic buffer) is 25 fA for a one second integration time, or equivalently 25 fC of charge, although the limit set by the electronic noise is 3.5 times smaller. Using our chip, we demonstrate the detection of DNA polymerization. The sensor can be used to sequence short DNA segments in addition to detect DNA hybridization in microarrays.