This paper presents a fully integrated pH-sensing system-on-ultra-thin-chip (SoUTC). Owing to lower thickness (~30µm) the presented chip can conform to curvilinear surfaces, such as human skin, allowing intimate contact necessary for robust data for continuous monitoring of analytes in body fluids. A current-mode active-pixel ISFET array architecture is presented, with a power consumption of 6.28μW per-pixel from a 2V power supply. The pH sensing SoUTC can operate either in a rolling shutter fashion or in a pseudo-random pixel selection mode allowing the simultaneous detection of pH from different skin regions. The results obtained from simulations and electrical and electrochemical characterization of the readout on both bulky and ultra-thin version of the chip are presented. The chips have been tested in aqueous Dulbecco’s Modified Eagle Medium (DMEM) solutions with 5-9 pH values.