Abstract: An electrochemical microarray chip to detect specific sequences of single-stranded DNA (ssDNA) or single-stranded RNA (ssRNA) target molecules in solution using a microarray of microspots of probe molecules immobilized on an electrode. The chip pertains to both regulating the immunospecific binding to the array of probes on the electrode and their subsequent detection on the microarray spots on the monolith electrode by electrochemical methods. The device can quantitatively measure the concentration of target molecules of specific sequence at high specificity and high sensitivity.