A metal oxide TFT-based sensor with multiple sensing modalities including an ion sensitive detector having an extended gate, a reservoir constructed to receive a sample carrying solution, and an ion sensitive electrode. The sensor further including a photodiode, a plurality of metal-oxide thin film transistors and a signal output. A pair of the metal-oxide thin film transistors are coupled to the photodiode, the ion sensitive detector and the output so as to provide output signals at the output alternately representative of ion emissions sensed by the ion sensitive detector and fluorescence events sensed by the photodiode.