A sensor-array based materials characterization apparatus includes a sensor array disposed on a substrate; electronic test circuitry for sending and receiving electrical signals; electronic circuitry for routing signals between selected sensors and the electronic test circuitry; and a computer or processor. Preferably, all or part of the electronic test and signal routing circuitry is contained on the same substrate as the sensor array. Additional circuitry and a processor or computer may be physically separate from the substrate carrying the sensor array, and may be connected to the sensor array substrate. During use, multiple samples are applied to the multiple sensors in the array, and signals are sent to and received from selected sensors. Integration of the electronic test and signal routing circuitry onto the same substrate as the sensor array allows for a high density of sensors on a single substrate, permitting rapid analysis of combinatorial libraries.