MEMS Sensors Overview
- 1. MEMS Sensors An introduction to MEMS sensors, current applications, and their future Presented by Jennifer Chin September 2nd, 2016 1
- 2. Preface 2
- 3. MEMS Sensors A system that uses mechanical devices and electrical signals Micro Electrical Sensing Mechanical Systems 3
- 4. How they Sense Capacitive Sensing Measures properties of conductive material Piezoelectric Sensing Measures properties by converting mechanical force into electrical charge Piezoresistive Sensing Measures properties by converting mechanical force into electrical resistance 4
- 5. Active Sensors Actively scans surroundings and compiles data to compare and measure changes Relies on transmissions and feedback to detect changes in the area of coverage Sends out a signal (i.e. microwave pulses, ultrasonic frequencies, or radio waves) that bounces off a target, and gathers data from the sensor upon reflection 5
- 6. Passive Sensors Detects and responds to inputs from the physical environment without producing any transmissions Passive sensors activate after detecting environmental inputs such as vibrations, light, radiation, heat, or other physical signals occurring in the sensor’s environment Ex. Mechanical Sensors 6
- 7. Types of MEMS Sensors 1. Inertial 2. Optical 3. Pressure 4. Chemical 7
- 8. Sensors in Use Today 8
- 9. iPhone 5s and Up 9 Main Sensors 1. Three-Axis Gyroscope 2. Accelerometer 3. Proximity Sensor 4. Ambient Light Sensor 5. Touch ID Fingerprint Sensor 3 4 5 1 2
- 10. 3-Axis Gyroscope and Accelerometer - Gyroscope: Sensor that assumes orientation through spinning wheel with free axis rotation - Uses: Autofocus on camera and landscape viewing of photos and keyboard - Accelerometer: Sensor that measures acceleration of a moving or vibrating object - Uses vary from Maps application to pedometers to app store games Passive/Inertial 10
- 11. Proximity Sensor - Shuts off illumination and touch sensitivity when sensor is activated - How it Works: Emits an electromagnetic beam and looks for changes in the return signal Active/Optical 11
- 12. Ambient Light Sensor - Senses lighting and adjusts screen brightness accordingly - How it Works: Uses a photodiode that converts light into current and voltage - Can perceive brightness just as our eyes can Passive/Optical 12
- 13. Touch ID Fingerprint Sensor - Scans finger to unlock iPhone - How it Works: Uses capacitive sensing to scan and read fingerprint - Capacitive Sensing: When a finger hits the screen, an electrical charge is transferred to the finger. This completes the circuit, creating a voltage drop at a specific point on the screen. Passive/Capacitive 13
- 14. iRobot: Roomba Uses sensors to navigate itself throughout room and vacuum Main Sensors: 1. Infrared Transmitter/Receiver 2. Object Sensor 3. Cliff Sensors 14 1 3 2
- 15. Infrared Transmitter/Receiver - Roomba uses infrared transmitter and receiver to roughly map out and measure the room - How it Works: The sensor sends out an infrared signal through the transmitter and analyzes the return time to the receiver Active/Optical 15
- 16. Object Sensor - When Roomba bumps into a wall or an object, it backs up and changes direction - How it Works: Behind the bumper is the object sensor. When the bumper retracts the object sensor is activated Passive/Inertial 16
- 17. Cliff Sensor - Roomba uses cliff sensors to avoid going down stairs - How it Works: The cliff sensors send out infrared signals. If they do not return immediately, Roomba changes direction. Active/Optical 17
- 19. Apple Watch: Heart Rate Sensor Measures heart rate throughout the day so users can check it at a glance Main Sensors: 1. Green LEDs 2. Infrared Light Blasters 3. Photodiode Sensors 19
- 20. Method 1: Green LEDs* 1. Green LEDs flash hundreds of times per second 1. Photodiode Sensor measures the absorption of the LEDs a. Red blood absorbs green light and reflects red light b. When blood is flowing, the absorption is higher than in between heart beats * High power consumption Active/Optical 20
- 21. Method 2: Infrared Light Blasters* 1. Infrared Light a. Shoots out to measure heart rate about every 10 minutes 1. Photodiode Sensor measures the absorption of infrared light a. Non-visible light can also be absorbed b. Same concept as Method 1 * Not as reliable as Green LEDs 21
- 22. Sensors in the Future 22
- 23. SCiO: Molecular Sensor Reads the chemical make up of materials using Near-Infrared sensors Main Sensor: 1. Near-Infrared Sensor (NIR) 23
- 24. Near-Infrared (NIR) Sensor SCiO uses the NIR optical sensor to read and analyze the chemical make up of organic materials How it Works: The NIR sensor emits a near-infrared light that is then reflected back from the object. The NIR light is broken down into a spectrum and read by the transmitter Optical/Active 24
- 25. Structure Sensor (3D Scanner) Portable device that takes a rapid 3D scan of objects and people Main Sensor: 1. Infrared Sensor 25
- 26. Infrared (IR) Sensor Structure Sensor uses two infrared sensors to measure the depth and distance of objects in order to create a 3D scan. How it Works: The IR sensor uses a specific receiver selected to read the IR signal. The receiver measures the intensity of the return signal and determines the distance of the object Active/Optical 26
- 27. 謝謝你的照顧和教導 27