Thermal Actuators

1. Thermal Actuators

2. Topic: Thermal Actuators Prepared by: McLain L. Cox Dept. of Electrical and Computer Engineering Utah State University 9 March 2004 ECE 5320 MechatronicsAssignment 1: Literature Survey on Sensors and Actuators

3. Outline • Reference List • To Explore Further • Intro on MEMS • How MEMS is useful • How MEMS is built • Thermal Actuators • Use in Optics

4. References • www.rl.af.mildiv/IFB/techtrans/datasheets/MEMS.html • www.imec.be/wwwinter/research/en/MEMS.shtml • www.rl.af.mildiv/IFB/techtrans/datasheets/MEMS.html • www.mems-exchange.org/MEMS/what-is.htm • www-g.eng.cam.ac.uk/edm/research/mems/mems.html • www.swri.edu/3pubs/IRD2000/15-9158.htm • www.sfu.ca/adm/heatuator.html • www.swri.edu/3pubs/IRD2000/15-9158.htm • www.memx.org

5. To Explore Further • Not much is out there on Thermal Actuators, but it is most commonly associated with MEMS. To find more information, look up as much as possible on MEMS. Thermal Actuators should be included there.

6. What is a Thermal Actuator • Thermal actuators are a part of the newest rage, MEMS • They are tiny actuators that move according to the heat that is given to them

7. What is MEMS • Micro • Electro- • Mechanical • System • Source www.rl.af.mildiv/IFB/techtrans/datasheets/MEMS.html

8. More on MEMS • MEMS are on a micrometer scale • They are proving very useful to nanotechnology • They consist of electrical and non-electrical components i.e. Mechanical, biochemical, and Optical • Source www.imec.be/wwwinter/research/en/MEMS.shtml

9. More on MEMS • compact information products which sense, process, store, and communicate information • enables the integration of digital, analog/RF, mechanical, and fluidic technologies all on a single silicon substrate in order to create micro-structures for sensing, actuating, control and data storage • Source www.rl.af.mildiv/IFB/techtrans/datasheets/MEMS.html

10. Some MEMS examples • personal digital assistants • smart munitions and decoys • wireless communicators • distributed sensor systems • inkjet print heads • pressure sensors • accelerometers in airbags • biochemical sensors • Sources www.imec.be/wwwinter/research/en/MEMS.shtml,www.rl.af.mildiv/IFB/techtrans/datasheets/MEMS.html

11. The beauty of MEMS • MEMS share the attributes of being size, weight, and cost driven; incorporate both digital and analog/RF functions; and may involve a limited amount of precision electro-mechanical assembly • Source www.rl.af.mildiv/IFB/techtrans/datasheets/MEMS.html

12. The Military uses MEMS for gathering information • Information exploitation is accomplished through interconnecting data processing, displays, batteries, mass storage, and input/output devices using advance telemetry interfaces. This class of system represents a large fraction of future DoD and commercial products. The integration of microdevices of a non-transistor nature in a monolithic system are now being called integrated microdevices • Source www.rl.af.mildiv/IFB/techtrans/datasheets/MEMS.html

13. How is MEMS created • fabricated by surface micromachining • built on same substrate as the chip • polycrystalline silicon is replaced by poly-SiGe • Source www.imec.be/wwwinter/research/en/MEMS.shtml

14. More on the creation of MEMS • While the electronics are fabricated using integrated circuit (IC) process sequences (e.g., CMOS, Bipolar, or BICMOS processes), the micromechanical components are fabricated using compatible "micromachining" processes that selectively etch away parts of the silicon wafer or add new structural layers to form the mechanical and electromechanical devices • Source http://www.mems-exchange.org/MEMS/what-is.html

15. MEMS as smart microsystems • Microelectronic integrated circuits can be thought of as the "brains" of a system and MEMS augments this decision-making capability with "eyes" and "arms", to allow microsystems to sense and control the environment • Sensors gather information from the environment through measuring mechanical, thermal, biological, chemical, optical, and magnetic phenomena • The electronics process the information derived from the sensors and through some decision making capability direct the actuators to respond by moving, positioning, regulating, pumping, and filtering, thereby controlling the environment for some desired outcome or purpose • Source http://www.mems-exchange.org/MEMS/what-is.html

16. How do Thermal Actuators fit in • One component of MEMS is Thermal Actuators • This one moves the bottom panel as it is heated and cooled. • Source www-g.eng.cam.ac.uk/edm/research/mems/mems.html

17. Thermal Actuators • This shows a horizontal thermal actuator at work. It is similar to the actuator in the previous slide. • Source http://www.swri.edu/3pubs/IRD2000/15-9158.htm

18. Thermal Actuators • Here is a vertical one. Instead of moving horizontally, it moves vertically. • Source http://www.swri.edu/3pubs/IRD2000/15-9158.htm

19. More on how Thermal Actuators work • When a voltage is applied to the terminals, current flows through the device. However, because of the different widths, the current density is unequal in the two arms. This leads to a different rate of Joule heating in the two arms, and thus to different amounts of thermal expansion. The thin arm is often referred to as the hot arm, and the wide arm is often referred to as the cold arm. • Source http://www.sfu.ca/adm/heatuator.html

20. Thermal actuators • Vertical actuators like this, are used in applications, like closing a switch. • Other applications are optics. This figure shows a vertical thermal actuator with integrated micromirror. Application of a current to the actuator arm produces vertical motion of the mirror, which can either reflect an optical beam or allow it to be transmitted. • Source http://www.swri.edu/3pubs/IRD2000/15-9158.htm

21. MEMS in optics • he greatest promise of microelectromechanical systems (MEMS) lies in the ability to produce mechanical motion on a small scale. Such devices are typically low power and fast, taking advantage of such microscale phenomenon as strong electrostatic forces and rapid thermal responses. Although MEMS-based sensors have been widely deployed, few MEMS-based actuators have achieved more than laboratory-level development due to the technical challenges they present. The market for such devices is growing rapidly, especially for optical and electronic applications. • Source http://www.swri.edu/3pubs/IRD2000/15-9158.htm

22. Optics • The explosive growth of data traffic, such as the Internet, has produced a pressing need for large-capacity optical networks. Optical switches are now in high demand in the telecommunications industry for their ability to reconfigure an optical network for traffic management or circuit protection without having to resort to low-bandwidth, protocol-dependent, opto-electronic conversions. To be widely deployed, such switches must be small, low cost, batch fabricated, and have a high port count. A MEMS-based optical switch is well suited to addressing these requirements. • Source http://www.swri.edu/3pubs/IRD2000/15-9158.htm

23. Micro-optical systems • Imagine a silicon chip with thousands of microscopic mirrors working in unison, enabling the all optical network and removing the bottlenecks from the global telecommunications infrastructure. • Source www.memx.org

24. Micro-optical systems • The explosive growth of data traffic, such as the Internet, has produced a pressing need for large-capacity optical networks. Optical switches are now in high demand in the telecommunications industry for their ability to reconfigure an optical network for traffic management or circuit protection without having to resort to low-bandwidth, protocol-dependent, opto-electronic conversions. To be widely deployed, such switches must be small, low cost, batch fabricated, and have a high port count. A MEMS-based optical switch is well suited to addressing these requirements. • Source http://www.swri.edu/3pubs/IRD2000/15-9158.htm