M.S. Roberto Jacobe Rodrigues (Ph.D. student)
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Transcript of M.S. Roberto Jacobe Rodrigues (Ph.D. student)
•M.S. Roberto Jacobe Rodrigues (Ph.D. student)
Flow and Gas Microsensors
•Dr. Rogerio Furlan
•B.S. Douglas Melman (M.S. student)
Microsensor structure
•Gas and liquid applications
•Suitable for small flow values
•Low power consumption
•Fast response
•Possibility of integration in microchannels
Heater
Sensor
Sensor
Analytical modelAnalytical model
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2,1 .4..2
1
R
Duu
D
Based on: T. S. J. Lammerink et al., “Micro-Liquid Flow Sensor,” Sensors and Actuators A37-A38, 45-50, 1993
externalsteady
laminarincompressible
u
Analytical modeling results for air flow
•Compromise: microsensor size x sensitivity x maximum flow range
2D Simulation with Ansis/Flotran
3 mm
300 µm
0 to 500 sccm(tube with D = 3 mm)
•Top: polysilicon ( ~ 0.6 µm)
•Bottom: nitride (~ 0.2 µm)
•10 µm wide
•200 µm long
•0.7 µm above substrate
Simulation results for air flow
increases with flow
•Good agreement for low flow velocities
•Heat dissipation byradial convection
velocity
Simulation results for gas detection
Filaments distance = 80 µm
•Difference in thermal diffusivity D = k/.c (m2/s)
40 mm
3 mm
-DCT300m X 300m
allows identification of gas contamination
Fabrication
Free-standing filaments
•Red light emission T ~ 1000 °C
Tests
Experimental results
Filaments distance = 120 µm
•Qualitative validation of simulations
ConclusionsConclusions
•Feasible microstructure for flow and gas Feasible microstructure for flow and gas microsensorsmicrosensors
•Good qualitative agreement between Good qualitative agreement between analytical and numerical models and analytical and numerical models and experimental resultsexperimental results
•Possibility of integration in Possibility of integration in microchannels of fluidic devicesmicrochannels of fluidic devices
•Possibility of immediate application for Possibility of immediate application for identification of flow presenceidentification of flow presence