A Low-Power 0.13-μm CMOS IC for ZnO-Nanowire Assembly and Nanowire-Based UV Sensor Interface

This paper presents a low-power system conceived for the integration and measurement of a nanowire (NW)-based sensor array onto a 130-nm CMOS technology process. Each array element includes a dielectrophoresis (DEP) signal generator for NWs alignment and a quasi-digital read-out circuit (ROC) for impedance conversion. The two subsystems can be digitally controlled by an external microcontroller which reads the ROC output and calculates the resistance and capacitance of the NW. Measurements show that the integrated two-quadrants quasi-digital ROC covers the range 1 M Omega-1 G Omega and 100 fF-1 mu F with a signal-to-noise ratio >= 44.89 dB. The CMOS system can be considered a building block for the implementation of a complete NW-based sensing array and each element, including both DEP and ROC subsystems, occupies an active area of 0.008 mm(2) and only consumes 14.76 mu W during read-out phase. The ROC has been also validated using an off-chip nanogap-based nanodevice integrating a single ZnO-NW which has been used as ultraviolet (UV) sensor during experiments. The device has been stimulated by an external UV source providing an irradiance >= 93 mu W/cm(2) to the nanodevice surface. We have proved that the ROC is able to measure the ZnO-NW electrical characteristics and their variations due to the photogenerated charge carriers.