A CMOS Read-Out IC for Cyanobacteria Detection with 40 nA_pp Sensitivity and 45-dB Dynamic Range

This paper presents a low-power high-sensitivity CMOS read-out integrated circuit (ROIC) realized in a 0.13 μm CMOS technology for cyanobacteria detection and monitoring with the current sensing capability of nano-ampere levels. The proposed CMOS ROIC consists of a current-conveyor transimpedance amplifier (CC-TIA) and a 9 bit successive approximation register (SAR) analog-to-digital converter (ADC). Electrically measured results of the proposed ROIC demonstrate 98.6 dB Ω transimpedance gain, 1.19 pA/&sqrt; Hz noise current spectral density, and 1.8 mA current consumption from a single 1.2 V supply. The ROIC can precisely recover the digital output codes corresponding to the input current levels of 40 nA_pp 7.2 μ A_pp (i.e., 45 dB dynamic range). Optical experiments utilizing a 405 nm wavelength laser source and a low-cost PIN-photodiode confirm the fluorescence intensity with respect to the quantity of cyanobacteria, demonstrating that the normalized voltage (QD₆₅₅/QD₅₆₅) is a linear function of the mcyD gene copy numbers. The CMOS ROIC chip occupies the area of 1.1 × 2.0