An embedded photosensor using a gate-body-tied (GBT) thin-film transistor is investigated on a low-temperature poly-silicon display panel. The GBT photosensor is formed by connection of the floating gate and body in a metal-oxide-semiconductor field-effect transistor (MOSFET). The intrinsic body region without gate metal on top is the photosensing area where the photogenerated electron-hole pairs are excited and separated. The GBT structure leads to photogenerated carrier accumulation on the floating gate and results in positive feedback of gate potential and increase of MOSFET current. Thus, the photocurrent is amplified. The photoresponse is enhanced to two to three times that of the conventional p-i-n photodiode.