Title :
Low-noise CMOS Fluorescence Sensor
Author :
Sander, David ; Dandin, Marc ; Ji, Honghao ; Nelson, Nicole ; Abshire, Pamela
Author_Institution :
Dept. of Electr. & Comput. Eng., Maryland Univ., College Park, MD
Abstract :
This paper reports a novel integrated circuit for fluorescence sensing. The circuit implements a differential readout architecture in order to reduce the overall noise figure. The circuit has been fabricated in a commercially available 0.5 mum CMOS technology. Preliminary results show that the reset noise is reduced by a factor of 1.42 and the readout noise by a factor of 9.20 when the pixel is operated in differential mode versus single-ended mode. Spectral responsivity characteristics show that the photodiodes are most sensitive at 480 nm. Using a commercially available emission filter, the sensor was able to reliably detect a concentration of Fura-2 as low as 39 nM. The sensor was used to perform ratiometric measurements and was able to reliably detect a free calcium concentration of 17 nM.
Keywords :
CMOS integrated circuits; biosensors; fluorescence; photoconductivity; photoemission; readout electronics; 0.5 micron; CMOS technology; differential readout architecture; fluorescence sensing; low-noise CMOS fluorescence sensor; photodiodes; ratiometric measurements; spectral responsivity characteristics; CMOS technology; Filters; Fluorescence; Integrated circuit noise; Integrated circuit technology; Noise figure; Noise reduction; Performance evaluation; Photodiodes; Sensor phenomena and characterization;
Conference_Titel :
Circuits and Systems, 2007. ISCAS 2007. IEEE International Symposium on
Conference_Location :
New Orleans, LA
Print_ISBN :
1-4244-0920-9
Electronic_ISBN :
1-4244-0921-7
DOI :
10.1109/ISCAS.2007.378431
