A CMOS Read-Out IC for Cyanobacteria Detection With 40 nA(pp) Sensitivity and 45-dB Dynamic Range

Abstract

This paper presents a low-power high-sensitivity CMOS read-out integrated circuit (ROIC) realized in a 0.13 mu m 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 Omega transimpedance gain, 1.19 pA/root 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 nApp similar to 7.2 mu App (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 x 2.0 mm(2).