In this study, a new Motion artifact (<1Hz) compensated (without any additional sensor), high sensing precision, wide dynamic range, and robust adaptive single-channel readout circuit is designed and developed for a new organic flexible PPG sensor to enhance the long-time continuous monitoring of the accurate heart rate. To achieve this, an auto-programmable and tunable band-pass trans-impedance amplifier with the continuous type DC-current cancellation loop is implemented in the analog front-end readout. The experiment result shows that the design readout circuit senses well as small as 1nA current, with a measured dynamic range >90dB (1nA to >100 µA). The total measured power consumption of the readout circuit is 460uW, while the power consumption of the integrated OLED driver is 1.8 mW.