A CMOS Read-Out IC for Cyanobacteria Detection With 40 nApp 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
$ {\mu }\text{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/
$\surd $
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
$\mu$
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 (QD
₆₅₅
/QD
₅₆₅
) is a linear function of the mcyD gene copy numbers. The CMOS ROIC chip occupies the area of 1.1
$\times$
2.0 mm
²
.