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Integrating metal-oxide-decorated CNT networks with a CMOS readout in a gas sensor.

Lee H, Lee S, Kim DH, Perello D, Park YJ, Hong SH, Yun M, Kim S - Sensors (Basel) (2012)

Bottom Line: The fabricated array of CNT sensors contains 128 sensor cells for added redundancy and increased accuracy.The read-out integrated circuit (ROIC) was combined with coarse and fine time-to-digital converters to extend its resolution in a power-efficient way.The ROIC is fabricated using a 0.35 μm CMOS process, and the whole sensor system consumes 30 mA at 5 V.

View Article: PubMed Central - PubMed

Affiliation: Department of Electrical Engineering, Seoul National University, Seoul, Korea. hyunjoong.lee@amic.snu.ac.kr

ABSTRACT
We have implemented a tin-oxide-decorated carbon nanotube (CNT) network gas sensor system on a single die. We have also demonstrated the deposition of metallic tin on the CNT network, its subsequent oxidation in air, and the improvement of the lifetime of the sensors. The fabricated array of CNT sensors contains 128 sensor cells for added redundancy and increased accuracy. The read-out integrated circuit (ROIC) was combined with coarse and fine time-to-digital converters to extend its resolution in a power-efficient way. The ROIC is fabricated using a 0.35 μm CMOS process, and the whole sensor system consumes 30 mA at 5 V. The sensor system was successfully tested in the detection of ammonia gas at elevated temperatures.

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Circuit schematic for CNT sensor array. Individual CNT cells can be measured via the 3 bit row decoder and 4 bit column decoder.
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f5-sensors-12-02582: Circuit schematic for CNT sensor array. Individual CNT cells can be measured via the 3 bit row decoder and 4 bit column decoder.

Mentions: Figure 5 shows the arrangement of the CNT sensor array circuit. A 7-bit digital code, ROWSEL[0:2] and COLSEL[0:3], assigned from outside the chip selects a single sensor cell. A 3-bit row decoder and a 4-bit column decoder respectively determines the row and column of the cell. When a CNT cell is connected to the ROIC, there exists a constant voltage drop across the CNT cell. This results from the voltage regulation loop inside the ROIC and produces a steady current through both cell and ROIC allowing the resistance of the CNT networks to be measured.


Integrating metal-oxide-decorated CNT networks with a CMOS readout in a gas sensor.

Lee H, Lee S, Kim DH, Perello D, Park YJ, Hong SH, Yun M, Kim S - Sensors (Basel) (2012)

Circuit schematic for CNT sensor array. Individual CNT cells can be measured via the 3 bit row decoder and 4 bit column decoder.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3376610&req=5

f5-sensors-12-02582: Circuit schematic for CNT sensor array. Individual CNT cells can be measured via the 3 bit row decoder and 4 bit column decoder.
Mentions: Figure 5 shows the arrangement of the CNT sensor array circuit. A 7-bit digital code, ROWSEL[0:2] and COLSEL[0:3], assigned from outside the chip selects a single sensor cell. A 3-bit row decoder and a 4-bit column decoder respectively determines the row and column of the cell. When a CNT cell is connected to the ROIC, there exists a constant voltage drop across the CNT cell. This results from the voltage regulation loop inside the ROIC and produces a steady current through both cell and ROIC allowing the resistance of the CNT networks to be measured.

Bottom Line: The fabricated array of CNT sensors contains 128 sensor cells for added redundancy and increased accuracy.The read-out integrated circuit (ROIC) was combined with coarse and fine time-to-digital converters to extend its resolution in a power-efficient way.The ROIC is fabricated using a 0.35 μm CMOS process, and the whole sensor system consumes 30 mA at 5 V.

View Article: PubMed Central - PubMed

Affiliation: Department of Electrical Engineering, Seoul National University, Seoul, Korea. hyunjoong.lee@amic.snu.ac.kr

ABSTRACT
We have implemented a tin-oxide-decorated carbon nanotube (CNT) network gas sensor system on a single die. We have also demonstrated the deposition of metallic tin on the CNT network, its subsequent oxidation in air, and the improvement of the lifetime of the sensors. The fabricated array of CNT sensors contains 128 sensor cells for added redundancy and increased accuracy. The read-out integrated circuit (ROIC) was combined with coarse and fine time-to-digital converters to extend its resolution in a power-efficient way. The ROIC is fabricated using a 0.35 μm CMOS process, and the whole sensor system consumes 30 mA at 5 V. The sensor system was successfully tested in the detection of ammonia gas at elevated temperatures.

Show MeSH