Micro electro mechanical systemsMODULE 2.pptx

Working principles of microsystems

1. DEPARTMENT OF ELECTRONICS & COMMUNICATION ENGINEERING MICRO ELECTRO MECHANICAL SYSTEMS – 18EC822 MODULE 2 : WORKING PRINCIPLES OF MICROSYSTEMS Course Coordinator: Prof. Namratha Dcruz Assistant Professor Dept. of ECE, VVIET

2. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 2 Course Outcomes After studying this course, students will be able to: Appreciate the technologies related to Micro Electro Mechanical Systems. Understand design and fabrication processes involved with MEMS devices. Analyze the MEMS devices and develop suitable mathematical models Know various application areas for MEMS device.

3. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 3 OVERVIEW Module 2: Working Principles of Microsystems: Introduction, Microsensors , Microactuation , MEMS with Microactuators , Microaccelerometers , Microfluidics. Engineering Science for Microsystems Design and Fabrication: Introduction, Molecular Theory of Matter and Intermolecular Forces, Plasma Physics, Electrochemistry Todays Session Introduction Acoustic Sensors Biomedical Sensors and Bio sensors

4. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 4 INTRODUCTION Rapid advance in microfabrication technologies has enabled new MEMS products to emerge in market Basic working principle of sensors Sensors : Acoustic Biomedical and bio sensors Chemical Optical Pressure Therma l

5. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 5 INTRODUCTION Actuation Techniques: Thermal force Shape memory alloy Piezoelectric crystals Electrostatic forces MEMS with Microactuators : microgripper , micromotor , microvalves , micropumps Microaccelerometers Microfluidics

6. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 6 INTRODUCTION

7. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 7 ACOUSTIC WAVE SENSOR Acoustic wave sensor does not related to the sensing of acoustic waves transmitted in solids or other media, as the name implies . Application is to measure chemical composition in gas Convert mechanical energy to electrical output. Actuation is through piezoelectric and magnetostrictive mechanisms Primary application of these sensors is to act like “band filters” in mobile telephones and base stations. Other applications include: Sensing of torques and tire pressures Sensing biological and chemical substances Sensing vapors, humidity and temperature Monitor fluid flow in microfluidics Actuate fluid flow in microfluidics

8. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 8 ACOUSTIC WAVE SENSOR 2 sets of “ Interdigital Transducers” ( IDT) are created on a piezoelectric layer attached to a tiny substrate as shown Energize by an AC source to the “Input IDT”will close and open the gaps of the finger electrodes, and thus surface deformation/ stresses transmitting through the piezo - electric material The surface deformation/stresses will cause the change of finger electrodes in the “Output IDT” Any change of material properties (chemical attacks) or geometry due to torques will alter the I/O between the “Input IDT” and “Output IDT.” The sensing of contact environment or pressure can thus be accomplished

9. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 9 BIOMEDICAL SENSOR The term “ BioMEMS ” has been a popular terminology in the MEMS industry in recent years due to the many break-through in this technology, which many believe to be a viable lead to mitigate the sky-rocketing costs in healthcare costs in many industrialized countries . BioMEMS include the following three major areas Biosensors for identification and measurement of biological substances Bioinstruments and surgical tools, and Bioanalytical systems for testing and diagnoses

10. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 10 BIOMEDICAL SENSOR

11. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 11 BIOMEDICAL SENSOR

12. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 12 BIOMEDICAL SENSOR

13. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 13 BIOMEDICAL SENSOR Working principle: The glucose in patient’s blood sample reacts with the O 2 in the polyvinyl alcohol solution and produces H2O2. Glucose +O2  gluconolactone +H2O2 The H 2 in H 2 O 2 migrates toward Pt film in a electrolysis process, and builds up The difference of potential between the two electrodes due to the build-up of H 2 in the Pt electrode relates to the amount of glucose in the blood sample

14. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 14 BIOMEDICAL SENSOR Working principle: The glucose in patient’s blood sample reacts with the O 2 in the polyvinyl alcohol solution and produces H2O2. Glucose +O2  gluconolactone +H2O2 The H 2 in H 2 O 2 migrates toward Pt film in a electrolysis process, and builds up The difference of potential between the two electrodes due to the build-up of H 2 in the Pt electrode relates to the amount of glucose in the blood sample

15. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 15 BIOMEDICAL SENSOR

16. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 16 BIOMEDICAL SENSOR Bio Testing and Analytical Systems

17. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 17 INTRODUCTION Sensors: Acoustic Biomedical and bio sensors Chemical Optical Pressure Therma l

18. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 18 CHEMICAL SENSORS

19. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 19 CHEMICAL SENSORS

20. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 20 CHEMICAL SENSORS

21. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 21 OPTICAL SENSORS

22. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 22 OPTICAL SENSORS

23. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 23 OPTICAL SENSORS Photo Conductive devices Devices that change their resistance upon exposure to incident radiation are called photo conducting devices Photoconductivity is an optical and electrical phenomenon in which a material becomes more electrically conductive due to the absorption of electromagnetic radiation such as visible light, ultraviolet light, infrared light, or gamma radiation

24. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 24 OPTICAL SENSORS Photodiodes A Photodiode is a special purpose p-n junction diode fabricated with a transparent window to allow light to fall on the diode. It is operated under reverse bias. When the photodiode is illuminated with light (photons) with energy ( hν ) greater than the energy gap ( Eg ) of the semiconductor , then electron-hole pairs are generated due to the absorption of photons. The diode is fabricated such that the generation of e-h pairs takes place in or near the depletion region of the diode.

25. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 25 OPTICAL SENSORS Photodiodes Due to electric field of the junction, electrons and holes are separated before they recombine . The direction of the electric field is such that electrons reach n-side and holes reach p-side. Electrons are collected on n-side and holes are collected on p-side giving rise to an emf . When an external load is connected, current flows. The magnitude of the photocurrent depends on the intensity of incident light

26. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 26 OPTICAL SENSORS

27. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 27 OPTICAL SENSORS A phototransistor is a bipolar or unipolar transistor where light can reach the base, creating optically generated carriers . This modulates the base-collector junction resulting in an amplified current through transistor action, which can lead to much greater photosensitivity.

28. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 28 PRESSURE SENSORS

29. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 29 PRESSURE SENSORS

30. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 30 PRESSURE SENSORS

31. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 31 PRESSURE SENSORS

32. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 32 PRESSURE SENSORS

33. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 33 THERMAL SENSORS

34. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 34 THERMAL SENSORS

35. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 35 THERMAL SENSORS

36. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 36 THERMAL SENSORS

37. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 37 MICRO ACTUATORS

38. ACTUATION TECHNIQUES 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 38 Actuation Techniques Actuation using Thermal Forces Actuation using Shape Memory Alloys Actuation using Piezoelectric Crystals Actuation using E lectrostatic Forces

39. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 39 ACTUATION TECHNIQUES

40. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 40 ACTUATION TECHNIQUES

41. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 41 ACTUATION TECHNIQUES

42. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 42 ACTUATION TECHNIQUES

43. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 43 ACTUATION TECHNIQUES

44. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 44 ACTUATION TECHNIQUES

45. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 45 ACTUATION TECHNIQUES

46. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 46 MEMS ACTUATORS

47. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 47 MEMS ACTUATORS

48. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 48 MEMS ACTUATORS

49. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 49 MEMS ACTUATORS

50. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 50 MEMS ACTUATORS

51. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 51 MEMS ACTUATORS

52. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 52 MEMS ACTUATORS

53. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 53 MEMS ACTUATORS

54. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 54 MEMS ACTUATORS Piezoelectrically actuated pump: An effective way to pump fluid through capillary tubes. Tube wall is flexible. Outside tube wall is coated with piezoelectric crystal film, e.g. ZnO with aluminum interdigital transducers (IDTs). Radio-frequency voltage is applied to the IDTs, resulting in mechanical squeezing in section of the tube (similar to the squeezing of toothpaste ) Smooth flow with “uniform” velocity profile across the tube cross section.

55. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 55 MICRO ACCELEROMETER Accelerometers is an instrument used to measure acceleration or deceleration Micro Accelerometers are used to detect associated dynamic forces in mechanical system in motion. Widely used in automobile industries as antilock braking system (ABS) ±2g range and Airbag deployment system ±50g range g represents gravitational acceleration having value of 9.8m/s^2 Also known as inertial sensor

56. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 56 MICRO ACCELEROMETER A typical accelerometer consists of a “ proof mass ” supported by a spring and a “ dashpot ” for damping of the vibrating proof mass In miniaturizing the accelerometers to the micro-scale , there is no room for the coil spring and the dashpot for damping on the vibrating mass. Alternative substitutes for the coil spring, dashpot, and even the proof mass need to be found.

57. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 57 MICRO ACCELEROMETER There are two types micro accelerometers available. (1) The cantilever beam accelerometer : (2 ) Balanced force micro accelerometer:

58. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 58 MICRO ACCELEROMETER Balanced force micro accelerometer used in inertial sensor:

59. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 59 MICRO ACCELEROMETER Balanced force micro accelerometer used in inertial sensor:

60. 6 June 2024 Dept. of E&C Engg., VVIET, Mysuru 60 MICRO FLUIDICS Microfluidics relates to design and study of devices which move or analyze tiny amount of liquid, smaller than a droplet