1. Slide 1a.1 Stiff Structures, Compliant Mechanisms, and MEMS: A short course offered at IISc, Bangalore, India. Aug.-Sep., 2003. G. K. Ananthasuresh Lecture 1a Role of Structures and Mechanisms in MEMS A general overview of structural aspects of MEMS.

2. Slide 1a.2 Stiff Structures, Compliant Mechanisms, and MEMS: A short course offered at IISc, Bangalore, India. Aug.-Sep., 2003. G. K. Ananthasuresh Contents Structures, Mechanisms, and MEMS Early MEMS devices Kinematic pairs and mechanisms in MEMS: excitement vs. practicality Deformable structures in MEMS Example 1: tilting micro-mirrors Example 2: micromanipulation

3. Slide 1a.3 Stiff Structures, Compliant Mechanisms, and MEMS: A short course offered at IISc, Bangalore, India. Aug.-Sep., 2003. G. K. Ananthasuresh Structures and Mechanisms Structures support and transmit loads. Mechanisms transfer/transform motion AND support and transmit loads. Another view: both transfer and transform energy (load*motion) There is no need to limit this energy to mechanical energy. Microelectromechanical Systems (MEMS) Most MEMS are sensors and actuators, i.e., they are transducers. Transducers are energy transformers and transmitters. If we limit MEMS to mechanical energy domain or if we expand the scope of energy in structures/mechanisms to other domains, the role of structures and mechanisms in MEMS is easily apparent. Willis

4. Slide 1a.4 Stiff Structures, Compliant Mechanisms, and MEMS: A short course offered at IISc, Bangalore, India. Aug.-Sep., 2003. G. K. Ananthasuresh Accepted size range for MEMS 1 nm0.1 um 10 um1 mm100 mm 10 m 10 nm1 um100 um10 mm1 m Atoms Molecules DNA Nanostructures Virus Smallest micro- electronic features NanotechnologyMicrosystemsMesoMacrosystems Bacteria Biological cells Dust particles Dia. of human hair MEMS Optical fibers Packaged ICs Packaged MEMS Lab-on-a-chip Plain old machines Humans Animals Plamts Planes, trains, and automobiles Precision machining Nano-machining Micro-machining Macro-machining

5. Slide 1a.5 Stiff Structures, Compliant Mechanisms, and MEMS: A short course offered at IISc, Bangalore, India. Aug.-Sep., 2003. G. K. Ananthasuresh MEMS devices in 1970’s and early 80’s Roylance L.M., Angell J.B. “A batch fabricated silicon accelerometer” IEEE Trans. on Electron Devices 26, 1911-1917 (1979) Schroeder C.M. "Accurate silicon spacer chips for an optical fiber cable connector" Bell. Syst. Tech. J. 57, 91-97 (1977) Petersen K.E. "Micromechanical light modulator array fabricated on silicon" Appl. Phys. Lett. 31, 521-523 (1977) Bassous E., Taub H.H., Kuhn L. “Ink jet printing nozzle arrays etched in silicon” Appl. Phys. Lett. 31, 135 (1977) Terry S.C., Jerman J.H., Angell J.B. “A gas chromatograph air analyzer fabricated on a silicon wafer” IEEE Trans on Electron Devices 26, 1880-1886 (1979) Ink-jet printer head Petersen K.E. “Silicon torsional scanning mirror” IBM J. Res. Dev. 24, 631-637 (1980) Micro mirrors for steering light Accelerometer Optical fiber connector Microfluidic device

6. Slide 1a.6 Stiff Structures, Compliant Mechanisms, and MEMS: A short course offered at IISc, Bangalore, India. Aug.-Sep., 2003. G. K. Ananthasuresh MEMS devices in 1970’s and early 80’s Stemme G. “A monolithic gas flow sensor with polyimide as thermal insulator” IEEE Trans. on Electron Devices TED-33, 1470-1464 (1986) Kimura K. “Microheater and microbolometer using microbridge of SiO2 film on silicon” Elect. Lett. 17, 80-82 (1981) Najafi K., Wise K.D., Mochizuki T. “A high-yield IC-compatible multichannel recording array” IEEE Trans on Electron Devices 32, 1206-1211 (1985) Ko W.-H., Hynecek J., Boettcher S.F. “Development of a miniature pressure transducer for biomedical applications” IEEE Trans. on Electron Devices T-ED26, 896-1905 (1979) Clark S.K., Wise K.D. “Pressure sensitivity in anisotropically etched thin diaphragm pressure sensors” IEEE Trans. on Electron Devices TED-26, 1887-1896 (1979) Pressure sensors Other types of sensors Gustafsson K., Hök B. “Fiberoptic switching and multiplexing with a micromechanical scanning mirror” Proc. 4th Int. Conf. on Solid-State Sensors and Actuators, Tokyo, June 3-5, P 212 (1987) Optical switching and multiplexing

7. Slide 1a.7 Stiff Structures, Compliant Mechanisms, and MEMS: A short course offered at IISc, Bangalore, India. Aug.-Sep., 2003. G. K. Ananthasuresh What is common to all those early MEMS devices? A beam or a diaphragm A bulk-micromachined silicon, glass, etc. Electrical and electronic components for sensing a signal Micro-electro-mechanical systems (MEMS)

8. Slide 1a.8 Stiff Structures, Compliant Mechanisms, and MEMS: A short course offered at IISc, Bangalore, India. Aug.-Sep., 2003. G. K. Ananthasuresh A MEMS accelerometer made in 1979 Roylance L.M., Angell J.B. “A batch fabricated silicon accelerometer” IEEE Trans. on Electron Devices 26, 1911-1917 (1979) Bulk micro machining Piezoresistor -based sensing

9. Slide 1a.9 Stiff Structures, Compliant Mechanisms, and MEMS: A short course offered at IISc, Bangalore, India. Aug.-Sep., 2003. G. K. Ananthasuresh Bulk micromachining (100) silicon (110) silicon (111) plane (111) With agitation Without agitation Isotropic etching Anisotropic etching Slanted surfaces

10. Slide 1a.10 Stiff Structures, Compliant Mechanisms, and MEMS: A short course offered at IISc, Bangalore, India. Aug.-Sep., 2003. G. K. Ananthasuresh Kinematic joint-based motion in MEMS The excitement began only after a rotary motor, revolute (pin) joints, and prismatic (sliding) joints were demonstrated. –At U. C. Berkeley, MIT, and Bell Labs –The reason for the excitement was batch- fabrication of “assembled” micro-mechanisms without assembly. –Crucial development: sacrificial layer process using polysilicon as the structural layer.

11. Slide 1a.11 Stiff Structures, Compliant Mechanisms, and MEMS: A short course offered at IISc, Bangalore, India. Aug.-Sep., 2003. G. K. Ananthasuresh M. Mehregany, K.J. Gabriel, and W.S.N. Trimmer, "Fabrication of Integrated Polysilicon Mechanisms," IEEE Trans. Electron Devices, vol. ED-35, no. 6, pp. 719-723, June 1988. M. Mehregany, S.F. Bart, L.S. Tavrow, J.H. Lang, S.D. Senturia, and M.F. Schlecht, "A Study of Three Microfabricated Variable-Capacitance Motors," Sensors and Actuators, vol. A21–A23, pp. 173-179, 1990. L.S. Fan, Y.C. Tai, R.S. Muller, "Integrated Movable Micromechanical Structures for Sensors and Actuators," IEEE Trans. on Electron Devices, Vol. ED-35, No. 6, pp. 724-730, June 1988. Y.C. Tai and R.S. Muller, "IC-processed Electrostatic Synchronous Motor," Sensors and Actuators, Vol. 20, No. 1&2, pp. 49- 56, Nov. 15, 1989. M. Mehregany, K.J. Gabriel, and W.S.N. Trimmer, "Micro Gears and Turbines Etched from Silicon," Sensors and Actuators, vol. 12, pp. 341-348, Nov./Dec. 1987 Early MEMS with kinematic joints Gears Revolute joints and linkages Micro rotary motors

12. Slide 1a.12 Stiff Structures, Compliant Mechanisms, and MEMS: A short course offered at IISc, Bangalore, India. Aug.-Sep., 2003. G. K. Ananthasuresh Electrostatic micro rotary motor MUMPs process (MCNC) Sacrificial layer process to make a revolute joint Ravi Jain, undergraduate at Penn.

13. Slide 1a.13 Stiff Structures, Compliant Mechanisms, and MEMS: A short course offered at IISc, Bangalore, India. Aug.-Sep., 2003. G. K. Ananthasuresh Sandia’s micro mechanisms Courtesy of Sandia laboratories, Albuquerque, New Mexico

14. Slide 1a.14 Stiff Structures, Compliant Mechanisms, and MEMS: A short course offered at IISc, Bangalore, India. Aug.-Sep., 2003. G. K. Ananthasuresh Sandia’s in-plane revolute joint Substrate Pin Rotor

15. Slide 1a.15 Stiff Structures, Compliant Mechanisms, and MEMS: A short course offered at IISc, Bangalore, India. Aug.-Sep., 2003. G. K. Ananthasuresh Floating in-plane revolute joints using only two structural layers Floating Pin Joints Fabricated From Two Layers of Polysilicon at the Micro Level ( Deanne Clements, Larry L. Howell, Nathan Masters, and Brent L. Weight) at Brigham Young University.

16. Slide 1a.16 Stiff Structures, Compliant Mechanisms, and MEMS: A short course offered at IISc, Bangalore, India. Aug.-Sep., 2003. G. K. Ananthasuresh Pister’s out-of-plane revolute joint A surface micromachined hinge (Kris Pister, Berkeley)

17. Slide 1a.17 Stiff Structures, Compliant Mechanisms, and MEMS: A short course offered at IISc, Bangalore, India. Aug.-Sep., 2003. G. K. Ananthasuresh Floating revolute joint Mask layout

18. Slide 1a.18 Stiff Structures, Compliant Mechanisms, and MEMS: A short course offered at IISc, Bangalore, India. Aug.-Sep., 2003. G. K. Ananthasuresh Why aren’t kinematic joints not well suited for MEMS? More difficult to fabricate Friction and wear –Main cause for structural failure Clearance in microfabricated kinematic joints is huge –Less accurate than deformable structures Some assembly may be required –Cannot be justified economically Not always amenable for different types of actuation Stiction –Surfaces in close proximity tend to stick together

19. Slide 1a.19 Stiff Structures, Compliant Mechanisms, and MEMS: A short course offered at IISc, Bangalore, India. Aug.-Sep., 2003. G. K. Ananthasuresh Example 1: tilting micro-mirrors: single-axis (Source: www.howstuffworks.com)

20. Slide 1a.20 Stiff Structures, Compliant Mechanisms, and MEMS: A short course offered at IISc, Bangalore, India. Aug.-Sep., 2003. G. K. Ananthasuresh Agere (Lucent)’s two-axis mirrors Raised above using Pister-type revolute joints Surpentine “torsional” springs -- to get large angles of rotation

21. Slide 1a.21 Stiff Structures, Compliant Mechanisms, and MEMS: A short course offered at IISc, Bangalore, India. Aug.-Sep., 2003. G. K. Ananthasuresh Steerable vertical mirrors Khiem Ng, Central High School, Philadelphia 2002 A surpentine torsional spring

22. Slide 1a.22 Stiff Structures, Compliant Mechanisms, and MEMS: A short course offered at IISc, Bangalore, India. Aug.-Sep., 2003. G. K. Ananthasuresh Example 2: Micro-manipulation of biological cells Laser tweezers and scissors operating on a cell (Berns, 1998) Cell injection using micro pipettes (Nelson, 2000)

23. Slide 1a.23 Stiff Structures, Compliant Mechanisms, and MEMS: A short course offered at IISc, Bangalore, India. Aug.-Sep., 2003. G. K. Ananthasuresh Polysilicon microgrippers C. J. Kim, A. Pisano, and R. S. Muller, Silicon-processes overhanging microgripper, JMEMS, Vol. 1, No. 1, 1992, pp. 31-36.

24. Slide 1a.24 Stiff Structures, Compliant Mechanisms, and MEMS: A short course offered at IISc, Bangalore, India. Aug.-Sep., 2003. G. K. Ananthasuresh Minimally invasive capture of cells using a micro cage C. J. Kim, UCLA Bi-metal cantilevers curled due to residual stress. Opened with actuating the bottom membrane

25. Slide 1a.25 Stiff Structures, Compliant Mechanisms, and MEMS: A short course offered at IISc, Bangalore, India. Aug.-Sep., 2003. G. K. Ananthasuresh Actuation in liquid environments is difficult CCD camera view of the micro device with a micro object Micro probe (top view) Markers Sponge Beam width = 375  m In-plane hydraulic/pneumatic actuation using a vertical membrane. Manipulation using compliant mechanisms

26. Slide 1a.26 Stiff Structures, Compliant Mechanisms, and MEMS: A short course offered at IISc, Bangalore, India. Aug.-Sep., 2003. G. K. Ananthasuresh Main points Kinematic joints in MEMS are cool but have limited (or no) practical use. Simple deformable structures have been used wisely by MEMS researchers. –Two examples to illustrate this point follow…

27. Slide 1a.27 Stiff Structures, Compliant Mechanisms, and MEMS: A short course offered at IISc, Bangalore, India. Aug.-Sep., 2003. G. K. Ananthasuresh Electrostatic comb-drive actuator– a clever structural design anchor Shuttle mass Folded-beam suspension Moving combs Fixed combs Misaligned parallel-plate capacitor

28. Slide 1a.28 Stiff Structures, Compliant Mechanisms, and MEMS: A short course offered at IISc, Bangalore, India. Aug.-Sep., 2003. G. K. Ananthasuresh Cancer detection using a cantilever A.Majumdar, Berkeley The presence of the virus makes the cantilevers bend.