One embodiment is a microprobe. An example of the microprobe comprises a housing having an aperture. This example of the microprobe also comprises an ISFET attached to the housing. The ISFET may have a gate located proximate the aperture. This example of the microprobe further comprises a reference electrode attached to the housing proximate the aperture. Another embodiment is a microsensor system. Another embodiment is a method for measuring a characteristic of tissue. Yet another condition embodiment is a method for monitoring tissue pH.