Microfluidic Actuators and Sensors Dr. Eliphas Wagner Simoes (Post-Doc) Dr. Rogerio Furlan

Microfluidic amplifiers No movable part Flow control Flow mixture 6 mm 18 mm

Microchannel Technology Silicon wet etching - KOH - 27,4 % in waterSilicon wet etching - KOH - 27,4 % in water Plasma etching - HDP plasma SF 6Plasma etching - HDP plasma SF 6 based - hidraulic diameters of ~ 40 µm Anodic bonding 377°C/ 800 VAnodic bonding - 377°C/ 800 V

Tests with gas (N 2 ) Supply (S) Cut-off Valve 1 Cut-off Valve 2 Sensor 1 (flow) Sensor 4 (flow) Sensor 5 (flow) Sensor 2 (flow) Sensor 1 (flow) chip holder plate Sensor 6 (pressure) Sensor 7 (pressure) Sensor 8 (pressure) Control 1 (C1) Control 2 (C2) Vent 1Vent 2 (O1) Output 1(O2) Output 2

1,01,52,02,53,03,54,04,55, Q O1 (sccm) Q C1 (sccm) Flow control results QSQS Q O2 Q C1 Q O1 Symmetrical behavior Non-zero output

Flow gain (  Q O /  Q C ) results High flow gain: up to 8

Flow ratio results  More uniform performance for small splitter angles

Analysis of internal flow with Ansys/Flotran Choked flow at the output of the supply nozzle

Analysis of internal flow with Ansys/Flotran Supersonic flow at the interaction region Possibility of shock waves formation

Analysis of internal flow with Ansys/Flotran Laminar to turbulent flow Continuum to slip flow

Main results for use with gas Feasibility for applications that require gas flow controlFeasibility for applications that require gas flow control Gain flow comparable to the obtained to devices with large dimensionsGain flow comparable to the obtained to devices with large dimensions Possibility of operation with internal disturbances (shock waves and turbulence) - application as flow mixerPossibility of operation with internal disturbances (shock waves and turbulence) - application as flow mixer Good basis for development of microfluidic oscillators for flow sensor applicationsGood basis for development of microfluidic oscillators for flow sensor applications

Microfluidic oscilattor Flow Measurement

Tests with liquids Supply flow: Isopropilic alcohol Acetone Distilled water Control flow: Nitrogen Liquids

Increasing supply flow Supply of liquids with nitrogen control Increasing control flow Possibility of control for alcohol and acetone Influence of viscosity, bubbles and hydrophobic effects for water

Increasing supply flow Supply of liquids with liquid control Increasing control flow Possibility of control for alcohol Pronounced formation of bubbles for acetone and water Flow throughout vents (Coanda Effect?)

Rapid prototyping of microfluidic switches in poly(dimethyl siloxane)and their actuation by electro-osmotic flow J. Micromech. Microeng. 9 (1999) 211– Department of Chemistry and Chemical Biology, Harvard University

Main results for use with liquids Promising results for control with gasPromising results for control with gas Strong influence of the type of liquid (viscosity)Strong influence of the type of liquid (viscosity) Possibility of hydrophobic effects - points to use of other materials and processesPossibility of hydrophobic effects - points to use of other materials and processes Can be operated with some level of suspended solids without clogging