A CMOS-integrated microinstrument for trace detection of heavy metals

This paper presents a voltammetric microsystem which includes CMOS-integrated sensors, electronic interface, and data conversion circuits for enabling cost-effective, in situ detection of trace metals. The system´s electronics were implemented in a 0.5 μm, 5 V, CMOS process and occupy 36 mm². Single-chip integration of the system was accomplished using post-CMOS, thin-film fabrication techniques. Due to its reduced ambient noise coupling and an integrated, pseudo-differential potentiostat, this design provides the best figures of merit for detection limit, area, and power published to date for heavy-metal microinstruments. The microsystem dissipates 16 mW and has successfully detected lead at concentrations of 0.3 ppb on 3.2×10^-5 cm² gold electrodes using subtractive anodic stripping voltammetry.