ECE5320 Mechatronics Assignment#01: Literature Survey on Sensors and Actuators Topic: Pressure Sensors

1. ECE5320 MechatronicsAssignment#01: Literature Survey on Sensors and Actuators Topic: Pressure Sensors Prepared by: Merin Swasey Dept. of Electrical and Computer Engineering Utah State University E: ; T: (435)797-; F: (435)797-3054 (ECE Dept.) W: http://mechatronics.usu.edu 3/10/2006

2. Outline • Reference list • To probe further • Major applications • Basic working principle illustrated • A typical sample configuration in application (application notes) • Major specifications • Limitations • And many more relevant issues in applications (such as, how to choose, cost information, where to buy etc.) ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

3. Reference list • www.honeywell.com (purchasing) • www.turck-usa.com (purchasing) • www.warf.com (information) • www.mems-issys.com (information) • www.medscape.com (information) ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

4. To explore further (survival pointers of web references etc) • Use specific search topics to find the type of pressure sensor and application you are looking for. • Use manufacturers websites to obtain the correct information about their specific sensors. • Research the type and tolerances to choose the specific sensor that will fit your application. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

5. Major applications • Automotive • Industrial • Air Flow Analysis • Medical • Robotics • Pumping • Stress Analysis ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

6. Silicon Pressure Sensors • Pressure sensors contain sensing elements that consist of four piezoresistors buried in the face of a thin, chemically-etched silicon diaphragm. A pressure change causes the diaphragm to flex, inducing a stress or strain in the diaphragm and the buried resistors. The resistor values change in proportion to the stress applied and produce an electrical output. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

7. Silicone Pressure Sensors Cont. Best Used For: Medical equipment: respiration, dialysis, infusion pump; HVAC, data storage, and gas chromatography equipment; process controls; industrial machinery; pumps; robotics; and off-road applications. Costs for extremely accurate sensors can be as low a $50. Pressure sensors are used in almost every industry and is widely used The following pressure sensors can be found at www.honeywell.com ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

8. Interesting Applications Cont. • Intercranial Pressure Monitoring System • Using the 140 PC pressure sensor an intercranial pressure monitoring system was designed where a probe is inserted into the patients skull and a portable pneumatic system monitors the changes of the system. Air enters and leaves the probe at a constant rate. Any changes in the system caused by leaks or other obstructions will set off an alarm so the problem can be addressed. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

9. Interesting Applications • Eye Pressure Testing • Called an oculocerebrovasculometer the eye pressure sensor measures the blood pressure in your eye to check to see if you have a glaucoma or stroke. • The procedure is non-invasive and is quick and painless. The technician uses a pen sized device with the measuring disk on the end and places it against your eyeball. • Stated from Honeywell “The measuring disc is located at the end of a piston that is floating frictionlessly in a cushion of frion gas. The gas goes in two directions to get out of the piston cylinder, forward toward the soft tip of the sensor, which is pressing lightly against the eyeball and backward to the micro switch pressure transducer.” ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

10. Turck Pressure Sensors The Turck pressure sensors are widely used in industry for manufacturing and controlling. The Turck sensor shown is also used in the hydraulic systems for current amusement park rides to monitor the load in the hydraulic system. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

11. Turck Pressure Sensors Specs. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

12. Turck Pressure Sensors Cont. As shown from the previous slide there is a very wide range of pressures that can be handled. The pressure sensor above is programmable and can even be used to measure negative pressures. Turck also offer a very wide variety of pressure sensors along with the type that you need whether it be NO or NC and they also offer different types of clean connections for them. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

13. 1800/1805 Series ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

14. 1800/1805 Series Cont. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

15. 1800/1805 Series Cont. The pressure is sensed by a change in voltage due to the differential pressure acting on the sensor. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

16. Ultra Low Pressure Sensing ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

17. Ultra Low Pressure Sensing Cont. • The Ultra Low Pressure Sensing sensor from Honeywell is one of the most precise pressure sensing elements on the market. The ULPS has the ability to dynamically adjust to changes in temperature thereby reducing the error in the measurements • The typical applications of the ULPS are used in medical instrumentation, environmental controls, and portable monitors. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

18. Ultra Low Pressure Sensing Cont. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

19. Capacitive Pressure Sensors Capacitive pressure sensors are made using thin metallic silicon wafers that are spaced apart and when pressure is applied to the sensor the capacitance changes in the sensor thereby allowing the measurement of change in pressure. Capacitive pressure sensors are inherently non-linear, but extensive FEA analysis has improved the linearity of these types of sensors. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

20. Capacitive Pressure Sensors Cont. • Benefits: • No need for an electrode inside the capsule • Does not require the extension of an electrical lead through a wall of the sealed cavity of the pressure sensor • Deformable structures of the sensor can be formed of conventional materials, such as crystalline silicon • More sensitive • Production is efficient and economical • The well-known three-mask dissolved wafer process is used, making this sensor much simpler to produce than many other pressure sensors that take up to six masks • Well suited to feedback control • It is projected that this pressure sensor will improve linearity and dynamic range ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

21. Capacitive Pressure Sensors Cont. As shown above the capacitive pressure sensor has a pretty good linear response. The picture on the right shows a capacitive pressure sensor. These data can be found at www.mems-issys.com ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

22. Other Applications Research has been done on using pressure sensors in a matrix format to simulate human skin which could eventually be used for robots. The focus for robots so far have been mainly visual and comprehensive movement. The next exciting step is to use these matrices of sensors to simulate human touch to control responses of the robot. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

23. Other Applications Cont. The medical industry has a wide variety of uses for pressure sensors. The fact that they are used in the medical industry, drives the manufacturers to design more robust and smaller pressure sensors. Smaller design of the pressure sensors allows them to be implanted into patients without the annoyance of noticing that something is there, such as on your arm or wrist. These implanted pressure sensors are a factor in preserving lives. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

24. Other Pressure Sensors Although almost all pressure sensors now used in industry are electronic, mechanical pressure sensors still exist. The bourdon tube for example is still used in many analog pressure gages and are extremely cheap and easy to make. Shown below is how the bourdon tube pressure sensor works. (e-funda.com) ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

25. Pressure Sensors Summary • Pressure sensors have a wide application for almost any pressure system that there is. • Pressure sensors have a wide range of sensitivities and accuracies that make it feasible for most applications. • Pressures sensors are relatively cheap and easy to produce. • Their response output is fairly linear. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators