Microsystems in Medical Applications Liquid Flow Sensors

Transkrypt

1 Microsystems in Medical Applications Liquid Flow Sensors Prezentacja multimedialna współfinansowana przez Unię Europejską w ramach Europejskiego Funduszu Społecznego w projekcie pt. Innowacyjna dydaktyka bez ograniczeń - zintegrowany rozwój Politechniki Łódzkiej - zarządzanie Uczelnią, nowoczesna oferta edukacyjna i wzmacniania zdolności do zatrudniania osób niepełnosprawnych Politechnika Łódzka, ul. Żeromskiego 116, Łódź, tel. (042)

2 Liquid Flow Basics Microsystems in Medical Applications 2 Liquid flow speed in a narrow round pipe depends on the distance from the pipe walls. On the edge of the wall flow speed is equal to zero and increase with approaching the middle of the pipe. Liquid Flow Direction

3 Microsystems in Medical Applications 3 Liquid Flow Basics contd. At each point in the fluid the flow lines pass over each other, exerting a force on each other. This force called shear force is given by: F du dy Where: viscosity U flow velocity y distance into the flow

4 Microsystems in Medical Applications 4 Viscosity The viscosity relates the shear force to the velocity gradient Viscosity can be divided by: dynamic (explained above) kinematics (dynamic viscosity to liquid density ratio)

5 Microsystems in Medical Applications 5 Flow Variety Laminar flow The motion of the fluid is dominated by viscose forces in the fluid. Turbulent flow The motion of the fluid is dominated by the inertial forces.

6 Reynolds Number Microsystems in Medical Applications 6 Definition: Re D Where: viscosity density D diameter If Re < 2000 laminar flow If Re > 2300 turbulent flow

7 Microsystems in Medical Applications 7 Microchannels Microchannel shape has a small influence on the Reynolds number. Trapezoidal shape of microchannel are the most popular in MEMS technology in case of a kind of silicon etching.

8 Microsystems in Medical Applications 8 Electrical Double Layer Most solid surfaces acuire a surface electric charge when brought into contact with an electrolyte (liquid). The spontaneous charging of surface layers appears. Between solid surface of the microchannel and liquids an electrical double layer is formed. It consists of: Stern layer ions are adsorbed onto the wall, Gouy-Chapman layer ions that are free to diffuse into the bulk fluid. After MEMS Handbook by M. Gad-el-Hak 2002 CRC Press.

9 Microsystems in Medical Applications 9 Electroosmotic Flow Electro-osmotic flow results when an electric field is applied through a liquid-filled microchannel having an EDL at the channel surfaces. This applied electric field introduces an electrostatic Lorentz body force. After MEMS Handbook by M. Gad-el-Hak 2002 CRC Press.

10 MEFS Structure Microsystems in Medical Applications 10 Micro-Electro-Fluid Systems

11 Electropherogram Microsystems in Medical Applications 11

12 Various Capillary Shapes Microsystems in Medical Applications 12

13 Summary Microsystems in Medical Applications 13 Liquid flow analysis is necessary to design microfluidic sensors Electrophoresis and electroosmosis are the basic phenomena used in semiconductor flow sensors Thanks to miniaturization of capillaries the lab-on-chip systems can be manufactured

14 Microsystems in Medical Applications 14 Sources Esteve D.: Barmint (Basic Research for Microsystems Integration) - Final Report, LAAS-CNRS, Toulouse, France 1997 Gad-el-Hak M.: The MEMS Handbook, CRC Press, USA 2002 Leondes C.T.: MEMS/NEMS Handbook, Techniques and Applications, Vol.5, Medical Applications and MOEMS, Springer, USA 2006 Maluf N., Williams K.: An Introduction to Microelectromechanical Systems Engineering, Artech House Inc Slusarczyk K., Napieralski A.: Developing the structure of the experimental MEFS, Proc. of the 2nd Int. Conference of Young Scientist, MEMSTECH, Lviv-Polyana, Ukraine 2006 STIMESI (Simulation Action on MEMS and SiP), UK,

15 Microsystems in Medical Applications Liquid Flow Sensors Prezentacja multimedialna współfinansowana przez Unię Europejską w ramach Europejskiego Funduszu Społecznego w projekcie pt. Innowacyjna dydaktyka bez ograniczeń - zintegrowany rozwój Politechniki Łódzkiej - zarządzanie Uczelnią, nowoczesna oferta edukacyjna i wzmacniania zdolności do zatrudniania osób niepełnosprawnych Politechnika Łódzka, ul. Żeromskiego 116, Łódź, tel. (042)