Crosstalk in Integrated Microarrays With Current Sensing

Various investigators have developed DNA microarrays with electronic readout; however, crosstalk between microarray pixels has received little attention. Electronic crosstalk can occur through the solution between electrodes, giving false results. Here we analyze crosstalk when an integrating readout scheme is used to measure the electrode current for multiplexed single electrode systems (e.g., charge sensing). Crosstalk between channels can easily exceed 10% and thus can be the dominant factor in the microarray limit-of-detection. The crosstalk depends on amplifier design (gain and integrating capacitance), electrode-solution impedance, integration time, and the profile of the measured current. Proper selection of the integration time, integration capacitance, amplifier pole frequency, and dc amplifier gain can reduce crosstalk considerably. The area required for an integrated circuit implementation trades off with crosstalk.