Contact CMOS imaging of gaseous oxygen sensor array.
We describe a compact luminescent gaseous oxygen (O2) sensor microsystem based on the direct integration of sensor elements with a polymeric optical filter and placed on a low power complementary metal-oxide semiconductor (CMOS) imager integrated circuit (IC). The sensor operates on the measurement of excited-state emission intensity of O2-sensitive luminophore molecules tris(4,7-diphenyl-1,10-phenanthroline) ruthenium(II) ([Ru(dpp)3]2+) encapsulated within sol-gel derived xerogel thin films. The polymeric optical filter is made with polydimethylsiloxane (PDMS) that is mixed with a dye (Sudan-II). The PDMS membrane surface is molded to incorporate arrays of trapezoidal microstructures that serve to focus the optical sensor signals on to the imager pixels. The molded PDMS membrane is then attached with the PDMS color filter. The xerogel sensor arrays are contact printed on top of the PDMS trapezoidal lens-like microstructures. The CMOS imager uses a 32 × 32 (1024 elements) array of active pixel sensors and each pixel includes a high-gain phototransistor to convert the detected optical signals into electrical currents. Correlated double sampling circuit, pixel address, digital control and signal integration circuits are also implemented on-chip. The CMOS imager data is read out as a serial coded signal. The CMOS imager consumes a static power of 320 µW and an average dynamic power of 625 µW when operating at 100 Hz sampling frequency and 1.8 V DC. This CMOS sensor system provides a useful platform for the development of miniaturized optical chemical gas sensors.
Department of Electrical and Computer Engineering, McGill University, 3480 University Street, Montreal, Quebec H3A2A7, Canada.
Daisy S
DS
Daivasagaya
Department of Electrical and Computer Engineering, McGill University, 3480 University Street, Montreal, Quebec H3A2A7, Canada.
Lei
L
Yao
Department of Chemistry, University at Buffalo, The State University of New York, Natural Sciences Complex, Buffalo, NY 14260-3000 USA.
Ka
K
Yi Yung
Department of Biomedical Engineering, Lebanese International University, Mazraa, Beirut, PO Box 146404, Lebanon.
Mohamad
M
Hajj-Hassan
Department of Electrical and Computer Engineering, McGill University, 3480 University Street, Montreal, Quebec H3A2A7, Canada.
Maurice C
MC
Cheung
Department of Electrical and Computer Engineering, McGill University, 3480 University Street, Montreal, Quebec H3A2A7, Canada.
Vamsy P
VP
Chodavarapu
Department of Chemistry, University at Buffalo, The State University of New York, Natural Sciences Complex, Buffalo, NY 14260-3000 USA.
Frank V
FV
Bright
CMOS imager; Contact imaging; Gas sensors; Luminescence; Microlens; O2 sensors; Optical sensors; PDMS; Xerogel thin-films