A sensor, comprising: a base substrate, a group of gate lines and a group of data lines arranged as crossing each other, and a plurality of sensing elements arranged in an array and defined by the group of gate lines and the group of data lines, each sensing element comprising a TFT device and a photodiode sensing device, wherein: the TFT device comprises: a gate electrode disposed on the base substrate and connected with a gate line; a gate insulating layer disposed on the gate electrode and overlaying the base substrate; a source electrode and a drain electrode disposed on the gate insulating layer and opposed to each other to form a channel region between the source electrode and the drain electrode, wherein the drain electrode is connected with a data line; an active layer disposed over the channel region; the photodiode sensing device comprises: a photodiode; an electrode disposed on the photodiode; and a bias line connected with the transparent electrode; characterized in that, the TFT device further comprises an ohmic layer disposed on the source electrode and the drain electrode, wherein the active layer is disposed on the ohmic layer; the photodiode sensing device further comprises a receiving electrode disposed on the gate insulating layer and connected with the source electrode, wherein the photodiode is disposed on the receiving electrode; the electrode disposed on the photodiode is an transparent electrode, and the bias line is disposed over the transparent electrode; the photodiode is a PIN photodiode comprising: an N-type semiconductor, a first part of an I-type semiconductor, a second part of the I-type semiconductor and a P-type semiconductor, wherein, the N-type semiconductor is positioned on the receiving electrode and is in the same pattern layer as the ohmic layer, the first part of the I-type semiconductor is positioned on the N-type semiconductor and is in the same pattern layer as the active layer, the second part of the I-type semiconductor is positioned on the first part of I-type semiconductor, and the P-type semiconductor is positioned on the second part of the I-type semiconductor. the TFT device comprises: a gate electrode disposed on the base substrate and connected with a gate line; a gate insulating layer disposed on the gate electrode and overlaying the base substrate; a source electrode and a drain electrode disposed on the gate insulating layer and opposed to each other to form a channel region between the source electrode and the drain electrode, wherein the drain electrode is connected with a data line; an active layer disposed over the channel region; the photodiode sensing device comprises: a photodiode; an electrode disposed on the photodiode; and a bias line connected with the transparent electrode; characterized in that, the TFT device further comprises an ohmic layer disposed on the source electrode and the drain electrode, wherein the active layer is disposed on the ohmic layer; the photodiode sensing device further comprises a receiving electrode disposed on the gate insulating layer and connected with the source electrode, wherein the photodiode is disposed on the receiving electrode; the electrode disposed on the photodiode is an transparent electrode, and the bias line is disposed over the transparent electrode; the photodiode is a PIN photodiode comprising: an N-type semiconductor, a first part of an I-type semiconductor, a second part of the I-type semiconductor and a P-type semiconductor, wherein, the N-type semiconductor is positioned on the receiving electrode and is in the same pattern layer as the ohmic layer, the first part of the I-type semiconductor is positioned on the N-type semiconductor and is in the same pattern layer as the active layer, the second part of the I-type semiconductor is positioned on the first part of I-type semiconductor, and the P-type semiconductor is positioned on the second part of the I-type semiconductor.