A sensor is provided for the detection of a marker in a sample in which
the sensor includes a high frequency 500 kHz-1 GHz piezoelectric ceramic
resonator, with the system measuring resonant frequency change. In one
embodiment, the piezoelectric sensor operates in the thickness
extensional (TE) mode, with the high frequency and TE mode permitting
fabrication of an exceptionally small size sensor capable of being
arrayed in a handheld unit.