Heavy metals are harmful even at trace concentrations because they accumulate in human organs causing long-term negative health effects. Lead, arsenic, and mercury have been cited in a 2003 U.S. government report as the three most critical hazardous substances in the environment, due to their toxicity and potential for human exposure [1]. Consequently, there is a great need for portable heavy metal microdetectors for a variety of scientific, industrial, commercial and home applications. Previously published voltammetric chemical detection systems which included separate sensors and electronics were not well suited for remote applications due to their large power dissipation [2][3]. Another system [4], integrated sensors and electronics, but did not achieve trace detection limits nor analyze metals. This paper presents a voltammetric microsystem which includes CMOS-integrated sensors, electronic interface, and mixed-signal circuits to enable remote detection of trace concentrations. The system's electronics are implemented in a 0.5µm CMOS process and occupy 36mm 2 . Single-chip integration of the system is accomplished using post-CMOS, thin-film fabrication techniques. Compared to similar systems, the authors believe this design provides the best published detection limit versus area and power trade-offs [2] [5], beause of the reduced ambient noise coupling and a pseudo-differential (PD) potentiostat. The PD potentiostat is an effective architecture for canceling solution matrix effects. The microsystem successfully detected lead using subtractive anodic stripping voltammetry (SASV).The pseudo-differential potentiostat is shown in Fig. 13.4.1. Assume that switches S p , S n , and S 1 are closed. The feedback around OP 3 and OP 4 forces two identical working electrodes WE p and WE n to a virtual ground. Feedback around OP 1 and OP 2 then ensures that the sensor's cell potential, V cell , tracks the source potential, V src . The faradaic currents from the two working electrodes flow through R f to form a pseudo-differential output voltage. Real-time SASV is implemented using the timing diagram shown in Fig. 13.4.1. First, S p is closed, which enables charge to flow through WE p . Switch S 1 is then closed, allowing the potentiostat to set the cell potential to V src . V src is then set to the deposition potential, E d , and the analyte is preconcentrated on WE p by electrochemical deposition. S n is closed some time later and preconcentration begins on that electrode. WE p undergoes deposition for a duration, t d , while WE n has a short deposition time, t ds . The subtraction of the currents from WE p and WE n during the voltammetric sweep nearly cancels all parasitic currents while preserving the analytical signal of interest. Figure 13.4.2 shows a block diagram of the entire voltammetric microsystem. The electronic instrumentation consists of a DAC, the PD potentiostat, a programmable gain amplifier (PGA), and an ADC. The DAC provides V src to the potentiostat and was implemented with a 10b, current-steering arch...