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. 2010;10(7):6594-611.
doi: 10.3390/s100706594. Epub 2010 Jul 9.

Design and characterization of a high resolution microfluidic heat flux sensor with thermal modulation

Sung-Ki Nam  1 , Jung-Kyun Kim, Sung-Cheon Cho, Sun-Kyu Lee
Affiliations

Design and characterization of a high resolution microfluidic heat flux sensor with thermal modulation

Sung-Ki Nam et al. Sensors (Basel). 2010.

Abstract

A complementary metal-oxide semiconductor-compatible process was used in the design and fabrication of a suspended membrane microfluidic heat flux sensor with a thermopile for the purpose of measuring the heat flow rate. The combination of a thirty-junction gold and nickel thermoelectric sensor with an ultralow noise preamplifier, a low pass filter, and a lock-in amplifier can yield a resolution 20 nW with a sensitivity of 461 V/W. The thermal modulation method is used to eliminate low-frequency noise from the sensor output, and various amounts of fluidic heat were applied to the sensor to investigate its suitability for microfluidic applications. For sensor design and analysis of signal output, a method of modeling and simulating electro-thermal behavior in a microfluidic heat flux sensor with an integrated electronic circuit is presented and validated. The electro-thermal domain model was constructed by using system dynamics, particularly the bond graph. The electro-thermal domain system model in which the thermal and the electrical domains are coupled expresses the heat generation of samples and converts thermal input to electrical output. The proposed electro-thermal domain system model is in good agreement with the measured output voltage response in both the transient and the steady state.

Keywords: electro-thermal domain model; heat flux sensor; microfluidic application; thermopile.

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Figures

Figure 1.
Figure 1.
Schematic of the microfluidic heat flux sensor.
Figure 2.
Figure 2.
Lengthwise cross section view.
Figure 3.
Figure 3.
Cross section of sensor part.
Figure 4.
Figure 4.
Fabrication steps for the microfluidic heat flux sensor.
Figure 5.
Figure 5.
Micrograph of the top of the completed sensor.
Figure 6.
Figure 6.
Schematic of the experimental setup.
Figure 7.
Figure 7.
Response time of the sensor using various heat fluxes.
Figure 8.
Figure 8.
Calibration of the measured heat flux versus sensor output voltage.
Figure 9.
Figure 9.
Resolution of the microfluidic heat flux sensor with the measured sensor output voltage and the input power of the heater.
Figure 10.
Figure 10.
Schematic of the microfluidic experimental setup.
Figure 11.
Figure 11.
Sensor output with various amounts of heat from the fluid input.
Figure 12.
Figure 12.
Heat power and different voltage output with various amounts of heat from the fluid input.
Figure 13.
Figure 13.
(a) Heat flow model of a fluid channel; (b) bond graph model of a fluid channel.
Figure 14.
Figure 14.
Bond graph model of (a) a heat flux sensor part and (b) values.
Figure 15.
Figure 15.
(a) Overall electrical circuit system; (b) Bond graph model of electrical circuit part.
Figure 16.
Figure 16.
Comparison of the heat-flux output for calibration (input conditions: reference Hz; 265 mVpp; 530 mVOffset; time constant 300 ms).
Figure 17.
Figure 17.
Fourier transform of the sensor output signal.
Figure 18.
Figure 18.
Comparison transient response of the heat-flux output with a fluid injection (input conditions: fluid injection: 350 nL; Ambient temperature: 20.1 °C; reference flow rate: 830 nL/s).
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References

    1. Diller TE. Advances in Heat Transfer. Vol. 23. Academic Press; Boston, MA, USA: 1993. Advances in heat flux measurement; pp. 279–368.
    1. Eminoglu S, Sabuncouglu Tezcan D, Yusuf Tanrikulu M, Akin T. Low-cost uncooled infrared detectors in CMOS process. Sensor. Actuator. A-Phys. 2003;109:102–113.
    1. Matsumiya M, Shin W, Izu N, Murayama N. Nano-structured thin-film Pt catalyst for thermoelectric hydrogen gas sensor. Sensor. Actuator. B-Chem. 2003;93:309–315.
    1. Baciocchi M, Bearzotti A, Gentili M, Lucchesini A. Cu/Pd Thin-film thermopile as a temperature and hydrogen sensor. Sensor. Actuator. A-Phys. 1990;22:631–635.
    1. Buchner R, Sosna C, Maiwald M, Benecke W, Lang W. A high-temperature thermopile fabrication process for thermal flow sensors. Sensor Actuator A-Phys. 2006;130–131:262–266.

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