Integrated measuring system for MEMS

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Integrated measuring system for MEMS Thermal characterization of gas flows under slip-flow regime Alice Vittoriosi May 16, 2011 I NSTITUTE FOR M ICRO P ROCESS

1 Integrated measuring system for MEMS Thermal characterization of gas flows under slip-flow regime Alice Vittoriosi May 16, 2011 I NSTITUTE FOR M ICRO P ROCESS E NGINEERING - T HERMAL P ROCESS E NGINEERING KIT University of the State of Baden-Wuerttemberg and National Laboratory of the Helmholtz Association

2 Outline 1 Introduction Objectives Measuring Principle 2 Experimental setup Integrated sensors Experimental device 3 Results 4 Conclusions & Outlook Alice Vittoriosi 64th IUVSTA Workshop May 16, /21

3 Outline 1 Introduction Objectives Measuring Principle 2 Experimental setup Integrated sensors Experimental device 3 Results 4 Conclusions & Outlook Alice Vittoriosi 64th IUVSTA Workshop May 16, /21

4 Objectives & Challenges Create a microchannel assembly with integrated temperature sensors: non invasive measuring system no limitations in the employable channel materials Develop an experimental setup for heat transfer studies in microchannels with different materials and geometries Demonstrate the functioning of the measuring system with rarefied gases: investigation on the gas-wall interactions possible influence of channel materials and roughness on the flow behavior Alice Vittoriosi 64th IUVSTA Workshop May 16, /21

5 Miniaturized temperature sensors Thermopiles Exploit the same thermoelectric effect of thermocouples Consist of junctions between two different materials connected in parallel (enhanced sensitivity) The two junction materials can be deposited over silicon substrates with planar micro-fabrication processes Usually manufactured on top of thin film membranes which avoid thermal shortcuts The signals correspond to the temperature difference across the membrane Alice Vittoriosi 64th IUVSTA Workshop May 16, /21

6 Miniaturized temperature sensors [Van Herwaarden et al. (1989)] Membrane layout: Alice Vittoriosi 64th IUVSTA Workshop May 16, /21

7 Miniaturized temperature sensors Resistance Temperature Detectors (RTD) The resistance is proportional to the absolute substrate temperature Four wire configurations present reduced noise Can be manufactured on silicon layers Can be used as reference for the thermopile signals Alice Vittoriosi 64th IUVSTA Workshop May 16, /21

8 Miniaturized temperature sensors Possible chip layout: T membrane = T chip + T Alice Vittoriosi 64th IUVSTA Workshop May 16, /21

9 Outline 1 Introduction Objectives Measuring Principle 2 Experimental setup Integrated sensors Experimental device 3 Results 4 Conclusions & Outlook Alice Vittoriosi 64th IUVSTA Workshop May 16, /21

10 Integrated sensors 8 thin film membranes 160 µm wide 16 thermopiles (on the two sides) 10 thermistors on the silicon frame Teflon support for assembly sealing and mechanical stability Alice Vittoriosi 64th IUVSTA Workshop May 16, /21

11 Integrated sensors Thermopile detail Alice Vittoriosi 64th IUVSTA Workshop May 16, /21

12 Cable bonding 4 flexible polyimide cables bonded on the chip Bonding with pressure/temperature cycles. Problem of short cuts or contact cross-talking originating during bonding (left) Introduction Alice Vittoriosi Experimental setup 64th IUVSTA Workshop Results Conclusions & Outlook May 16, /21

13 Experimental device Multi-layer design Exchangeable test sections Fixed sensor layer (channel fourth wall) Variable thermal boundary conditions Top cover Sensor foil Channel foil Heating/cooling units Base Alice Vittoriosi 64th IUVSTA Workshop May 16, /21

14 Experimental device Integrated sensors Multi-layer device Test sections Assembled device Introduction Alice Vittoriosi Experimental setup 64th IUVSTA Workshop Results Conclusions & Outlook May 16, /21

15 Outline 1 Introduction Objectives Measuring Principle 2 Experimental setup Integrated sensors Experimental device 3 Results 4 Conclusions & Outlook Alice Vittoriosi 64th IUVSTA Workshop May 16, /21

16 RTD calibration Reference signals: thermocouple type K on the heating blocks Assembly kept at constant temperature by electrical heating Steady state signals recorded Good and fast signal response of the thermistors No drift in time Least square fitting to retrieve the calibration coefficients Good linear behavior Limited temperature window for mechanical stability problems (T max 75 C) Alice Vittoriosi 64th IUVSTA Workshop May 16, /21

17 RTD calibration Reference signals: thermocouple type K on the heating blocks Assembly kept at constant temperature by electrical heating Steady state signals recorded Good and fast signal response of the thermistors No drift in time Least square fitting to retrieve the calibration coefficients Good linear behavior Limited temperature window for mechanical stability problems (T max 75 C) Alice Vittoriosi 64th IUVSTA Workshop May 16, /21

18 RTD calibration Reference signals: thermocouple type K on the heating blocks Assembly kept at constant temperature by electrical heating Steady state signals recorded Good and fast signal response of the thermistors No drift in time Least square fitting to retrieve the calibration coefficients Good linear behavior Limited temperature window for mechanical stability problems (T max 75 C) Alice Vittoriosi 64th IUVSTA Workshop May 16, /21

19 RTD calibration Reference signals: thermocouple type K on the heating blocks Assembly kept at constant temperature by electrical heating Steady state signals recorded Good and fast signal response of the thermistors No drift in time Least square fitting to retrieve the calibration coefficients Good linear behavior Limited temperature window for mechanical stability problems (T max 75 C) Alice Vittoriosi 64th IUVSTA Workshop May 16, /21

20 RTD calibration Reference signals: thermocouple type K on the heating blocks Assembly kept at constant temperature by electrical heating Steady state signals recorded Good and fast signal response of the thermistors No drift in time Least square fitting to retrieve the calibration coefficients Good linear behavior Limited temperature window for mechanical stability problems (T max 75 C) Alice Vittoriosi 64th IUVSTA Workshop May 16, /21

21 Thermopile calibration Imposed temperature difference across the membrane Reference signals: Calibrated thermistors on the chip Thermocouple type K on the heating blocks High basic noise: Contact interferences on the cable bonding area Filtering of the signals necessary Alice Vittoriosi 64th IUVSTA Workshop May 16, /21

22 Thermopile calibration Imposed temperature difference across the membrane Reference signals: Calibrated thermistors on the chip Thermocouple type K on the heating blocks High basic noise: Contact interferences on the cable bonding area Filtering of the signals necessary Alice Vittoriosi 64th IUVSTA Workshop May 16, /21

23 Thermopile calibration Imposed temperature difference across the membrane Reference signals: Calibrated thermistors on the chip Thermocouple type K on the heating blocks High basic noise: Contact interferences on the cable bonding area Filtering of the signals necessary Alice Vittoriosi 64th IUVSTA Workshop May 16, /21

24 Outline 1 Introduction Objectives Measuring Principle 2 Experimental setup Integrated sensors Experimental device 3 Results 4 Conclusions & Outlook Alice Vittoriosi 64th IUVSTA Workshop May 16, /21

25 Conclusions An integrated microchannel system with miniaturized temperature sensors has been realized: minimal flow disturbance exchangeable channels with fixed measuring system Preliminary tests for the sensor calibration have been performed Noise problems have been encountered for the thermopiles The chips present mechanical and thermal stability issues The sensors showed an overall good behavior in detecting the chip and the gas temperatures Alice Vittoriosi 64th IUVSTA Workshop May 16, /21

26 Outlook Further experiments with rarefied gases will be done to investigate the local gas-wall interactions Different materials and surface characteristics will be used for the channels New chips with optimized cable bonding procedure and expected reduced noise have been manufactured and should be tested Different assembly configuration could be investigated to improve the chip mechanical stability and broaden the allowable test conditions The present sensor technology can be adapted to many other processes where online monitoring and actuation are required Alice Vittoriosi 64th IUVSTA Workshop May 16, /21

27 Outlook Further experiments with rarefied gases will be done to investigate the local gas-wall interactions Different materials and surface characteristics will be used for the channels New chips with optimized cable bonding procedure and expected reduced noise have been manufactured and should be tested Different assembly configuration could be investigated to improve the chip mechanical stability and broaden the allowable test conditions The present sensor technology can be adapted to many other processes where online monitoring and actuation are required Alice Vittoriosi 64th IUVSTA Workshop May 16, /21

28 Thank you! The research leading to these results has received funding from the European Community s Seventh Framework Program (FP7/ ) under grant agreement n Alice Vittoriosi 64th IUVSTA Workshop May 16, /21

MICROMECHANICAL TEMPERATURE SENSOR

MICROMECHANICAL TEMPERATURE SENSOR Ralitza Simeonova Gjosheva 2, Krassimir Hristov Denishev 1 1 Department of Microelectronics, Technical University - Sofia, 8 Kliment Ohridski Blvd., bl. 1, 1797-Sofia,