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CMOS integration of inkjet-printed graphene for humidity sensing.

Santra S, Hu G, Howe RC, De Luca A, Ali SZ, Udrea F, Gardner JW, Ray SK, Guha PK, Hasan T - Sci Rep (2015)

Bottom Line: The graphene ink is produced via ultrasonic assisted liquid phase exfoliation in isopropyl alcohol (IPA) using polyvinyl pyrrolidone (PVP) polymer as the stabilizer.When the sensors are exposed to relative humidity ranging from 10-80%, we observe significant changes in resistance with increasing sensitivity from the amount of graphene in the inks.Our sensors show excellent repeatability and stability, over a period of several weeks.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Indian Institute of Technology, Kharagpur, 721302, India.

ABSTRACT
We report on the integration of inkjet-printed graphene with a CMOS micro-electro-mechanical-system (MEMS) microhotplate for humidity sensing. The graphene ink is produced via ultrasonic assisted liquid phase exfoliation in isopropyl alcohol (IPA) using polyvinyl pyrrolidone (PVP) polymer as the stabilizer. We formulate inks with different graphene concentrations, which are then deposited through inkjet printing over predefined interdigitated gold electrodes on a CMOS microhotplate. The graphene flakes form a percolating network to render the resultant graphene-PVP thin film conductive, which varies in presence of humidity due to swelling of the hygroscopic PVP host. When the sensors are exposed to relative humidity ranging from 10-80%, we observe significant changes in resistance with increasing sensitivity from the amount of graphene in the inks. Our sensors show excellent repeatability and stability, over a period of several weeks. The location specific deposition of functional graphene ink onto a low cost CMOS platform has the potential for high volume, economic manufacturing and application as a new generation of miniature, low power humidity sensors for the internet of things.

No MeSH data available.


Related in: MedlinePlus

Temperature versus input power testing with the correlation coefficient r given.
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f2: Temperature versus input power testing with the correlation coefficient r given.

Mentions: The characteristic power versus temperature plot (up to 217 °C) of the μHP device is given in Fig. 2. To calculate the power consumption, the resistive μHPs are first calibrated to up to 300 °C using a computer controlled high temperature chuck (Signatone S-1060R-6TG). Two temperature coefficients of resistance (α, β) are calculated from the measured value using the relationship: , where is the resistance of the heater at room temperature , and is the temperature increase. The values of α (2.05 × 10−3 K−1) and β (0.2 × 10−6 K−2) are very closely matched to the values provided by the CMOS foundry. A constant current is supplied to the HP and the voltage is measured across the heater. From the constant current and measured voltage, the power supplied to the devices is calculated. The corresponding heater temperature is calculated from the change in resistance using , values estimated during the calibration. Over small temperature changes, a linear function is fitted through the experimental points of power versus temperature plot, yielding an electrothermal transduction efficiency of 8.46 °C/mW; Fig. 2.


CMOS integration of inkjet-printed graphene for humidity sensing.

Santra S, Hu G, Howe RC, De Luca A, Ali SZ, Udrea F, Gardner JW, Ray SK, Guha PK, Hasan T - Sci Rep (2015)

Temperature versus input power testing with the correlation coefficient r given.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4663628&req=5

f2: Temperature versus input power testing with the correlation coefficient r given.
Mentions: The characteristic power versus temperature plot (up to 217 °C) of the μHP device is given in Fig. 2. To calculate the power consumption, the resistive μHPs are first calibrated to up to 300 °C using a computer controlled high temperature chuck (Signatone S-1060R-6TG). Two temperature coefficients of resistance (α, β) are calculated from the measured value using the relationship: , where is the resistance of the heater at room temperature , and is the temperature increase. The values of α (2.05 × 10−3 K−1) and β (0.2 × 10−6 K−2) are very closely matched to the values provided by the CMOS foundry. A constant current is supplied to the HP and the voltage is measured across the heater. From the constant current and measured voltage, the power supplied to the devices is calculated. The corresponding heater temperature is calculated from the change in resistance using , values estimated during the calibration. Over small temperature changes, a linear function is fitted through the experimental points of power versus temperature plot, yielding an electrothermal transduction efficiency of 8.46 °C/mW; Fig. 2.

Bottom Line: The graphene ink is produced via ultrasonic assisted liquid phase exfoliation in isopropyl alcohol (IPA) using polyvinyl pyrrolidone (PVP) polymer as the stabilizer.When the sensors are exposed to relative humidity ranging from 10-80%, we observe significant changes in resistance with increasing sensitivity from the amount of graphene in the inks.Our sensors show excellent repeatability and stability, over a period of several weeks.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Indian Institute of Technology, Kharagpur, 721302, India.

ABSTRACT
We report on the integration of inkjet-printed graphene with a CMOS micro-electro-mechanical-system (MEMS) microhotplate for humidity sensing. The graphene ink is produced via ultrasonic assisted liquid phase exfoliation in isopropyl alcohol (IPA) using polyvinyl pyrrolidone (PVP) polymer as the stabilizer. We formulate inks with different graphene concentrations, which are then deposited through inkjet printing over predefined interdigitated gold electrodes on a CMOS microhotplate. The graphene flakes form a percolating network to render the resultant graphene-PVP thin film conductive, which varies in presence of humidity due to swelling of the hygroscopic PVP host. When the sensors are exposed to relative humidity ranging from 10-80%, we observe significant changes in resistance with increasing sensitivity from the amount of graphene in the inks. Our sensors show excellent repeatability and stability, over a period of several weeks. The location specific deposition of functional graphene ink onto a low cost CMOS platform has the potential for high volume, economic manufacturing and application as a new generation of miniature, low power humidity sensors for the internet of things.

No MeSH data available.


Related in: MedlinePlus