Design and Evaluation of a MEMS Bimetallic Thermal Actuator for Viscosity Measurements

A non-cantilever-beam micro-electro-mechanical (MEMS) based viscosity sensor is proposed. This novel vibration viscometer device utilizes thermal actuation and piezoresistive sensing. As the actuation bias is kept constant, viscosity changes can be correlated to changes in the oscillation amplitude. This proposed solution is CMOS compatible, inexpensive and reliable. This paper investigates the vertical movement of thin silicon/aluminum bimetal diaphragms with varying bimetal areas and diaphragm thickness to better understand the thermo- mechanical behavior of the proposed actuator/sensor device. Proof of concept results are presented in which the oscillation amplitude of the bimetal actuator changes when the device is immersed in media of different viscosity.

[1]  Q. Zou,et al.  A study on micromachined bimetallic actuation , 1999 .

[2]  A. Lal,et al.  Silicon Ultrasonic Horn Driven Microprobe Viscometer , 2006 .

[3]  R. L. Smith,et al.  Thermally actuated, bistable, oxide/silicon/metal membranes , 2005 .

[4]  R. Plunkett,et al.  Formulas for Stress and Strain , 1965 .

[5]  Bruno Mercier,et al.  A microfluidic MEMS sensor for the measurement of density and viscosity at high pressure , 2007, SPIE MOEMS-MEMS.

[6]  Liviu Nicu,et al.  Micromachined piezoelectric membranes with high nominal quality factors in newtonian liquid media : A Lamb's model validation at the microscale , 2007 .

[7]  John E. Sader,et al.  Experimental validation of theoretical models for the frequency response of atomic force microscope cantilever beams immersed in fluids , 2000 .

[8]  J. Sader.  Frequency response of cantilever beams immersed in viscous fluids with applications to the atomic force microscope , 1998 .

[9]  A. Ramkumar,et al.  P1I-7 Silicon Ultrasonic Horn Driven Microprobe Viscometer , 2006, 2006 IEEE Ultrasonics Symposium.

[10]  Victor M. Bright,et al.  Deformation and structural stability of layered plate microstructures subjected to thermal loading , 2002 .

[11]  C. Atkinson,et al.  Theoretical model on the interaction of a vibrating beam and the surrounding viscous fluid with applications to density and viscosity sensors , 2004, Proceedings of IEEE Sensors, 2004..

[12]  G. G. Stokes.  "J." , 1890, The New Yale Book of Quotations.

[13]  Vibrating Microcantilever used as Viscometer and Microrheometer , 2006, 2006 5th IEEE Conference on Sensors.

[14]  Robert Puers,et al.  On the mechanisms in thermally actuated composite diaphragms , 1998 .

[15]  M. Al-Nimr,et al.  BEHAVIOR OF THERMAL STRESSES IN A RAPIDLY HEATED THIN PLATE , 2000 .

[16]  Daniel Boley,et al.  A simple method to determine the stability and margin of stability of 2-D recursive filters , 1992 .

[17]  Miss A.O. Penney.  (b) , 1974, The New Yale Book of Quotations.

[18]  BEHAVIOR OF THERMAL STRESSES IN A RAPIDLY HEATED THIN PLATE , 2000 .