Surface modifications to sensors in an array give the sensors different functionalities for adsorbing or binding molecules. A first sensor in the array includes a first resonating member having a first surface comprising a receptor material coated over a first underlying material. A second sensor includes a second resonating member having a second surface comprising the receptor material coated over a second underlying material that is different than the first underlying material. The first underlying material, the second underlying material, and the receptor material are selected such that the first resonating member, having a combination of the receptor material and the first underlying material, has a different ability to adsorb or bind a mass of one or more analytes than does the second resonating member having a combination of the receptor material with the second underlying material. Methods for fabricating sensors with surface modifications are also provided.