This paper presents an electrochemical sensing chip with an integrated current-reducer pattern generator and a low-noise chopper-stabilization potentiostat circuit. The pattern generator, utilizing the current reducer technique and pseudo resistors, creates a sub-Hz ramp signal for the cyclic voltammetric measurement without large-size passive components. The proposed design adopts a chopper-stabilization potentiostat and time-based converter to reduce the amplitude noise effects. The design is fabricated using a 0.18-μm CMOS process and achieves a 41pA current resolution in the current range of ± 5μA while maintaining the R2 linearity of 0.998. The power consumption of the design is 16μW when a 5μA sensing current is detected. The power efficiency of the readout interface is 0.31 and the sensing current dynamic range is 108dB. The design is fully integrated into a single chip.