What are MEMS Sensors? Types, Applications

In this tutorial, we will learn about an interesting technology called MEMS. We will see some basic concepts of MEMs and also take a look at the applications of MEMS in the form of MEMS Sensors. We will also learn about different types of MEMS Sensors and some of the current applications.

What is MEMS?

MEMS is short for Micro Electro Mechanical Systems. It is a technology associated with manufacturing of microscale devices like Sensors, Transducers, Actuators, Gears, Pumps, Switches etc.

In other words, MEMS are microscopic integrated devices that are a combination of electronics, electrical and mechanical elements, all working together for a single functional requirement using a technology called Microsystems Technology (MST).

The MEMS technology is considered to be an extended form of traditional integrated circuit (IC) manufacturing. The main difference between the traditional IC Manufacturing technology (VLSI) and MEMS is that using MEMS you can not only fabricate electrical components like Capacitors and Inductors but also mechanical components like gears, springs, beams etc. Using traditional IC Technology, you can only fabricate conductors, insulators, diodes and transistors.

The size of these MEMS Based devices is usually in the order of few micrometers (between 1 to 100 micrometers).

Another important point to remember is that MEMS is an integration of both active and passive components into a single silicon substrate with the help of advanced IC manufacturing technology. The active components are the Sensors and Actuators while the passive components are the passive electronic systems and passive mechanical systems.

The electronic system, which consists of the signal processing circuits like Amplifier, ADC, Filters etc. is designed using IC Fabrication Process while the mechanical system, which consists of Gears, Cranks, Bearings etc. is designed using Micromachining Process.

What are MEMS Sensors?

Sensors are one of the important components of today’s digital World. Since all the computation and processing is done on digital signals, there should be a medium between the analog world and the digital electronics. Sensors bridge this gap as they are used to observe the temporal effects of analog physical parameters and produce a meaningful information (to the computer).

Modern definition of a Sensor is confusing at times but in simple words a Sensor is a device that contains basic sensing elements which sense the physical quantity like temperature or humidity and convert it into an electrical signal. A sensor also consists of a signal processing unit like an amplifier, filter or ADC or a combination of these elements.

Coming to MEMS Sensors, if a Sensor is designed and manufactured using the MEMS Technology, then it is called a Micromachined Microsensor or simply a MEMS Sensor.

If you remember our HAND GESTURE CONTROLLED ROBOT, we used an MPU6050 IC. It contains a 3-axis Accelerometer, a 3-axis Gyroscope and a Digital Motion Processor. It is fabricated using MEMS Technology.

Different Types of MEMS Sensors

One of the major implementors of MEMS technology is the automotive industry. Modern cars use a lot of sensors and most of them are MEMS based devices. The following is a list of MEMS Sensors that are used in a modern car.

• Accelerometers – For Electronic Stability Control and Airbag deployment.
• Inertial Measurement Units or IMU (they are combination of MEMS Accelerometer and MEMS Gyroscope) – For measuring yaw, pitch and roll for autonomous driving.
• Magnetometer – For direction used in navigation.
• Pressure and Inertial Sensor – For braking control.
• Pressure Sensor – Tire Pressure Monitoring System.
• Airflow Sensor – Air intake monitoring.
• Fuel Sensor – Fuel Level Indicator.
• Impact and Crash Sensor – Impact detection and Airbag deployment.
• MEMS Microphone – For communication and Noise Cancellation.
• Temperature Sensor – For Automatic Climate Control and Engine Temperature Monitoring.
• There are many other MEMS based devices for various applications.

Applications

MEMS Sensors are already being used in a variety of applications like controlling and handling equipment, managing robots, cars, grippers, etc. You can find these sensors in modern ink jet printers, Colour Projectors, Display Systems, Clocks and Scanning equipment.

MEMS Technology is used to manufacture different sensors like Pressure, Temperature, Vibration and Chemical Sensors.

Accelerometers, Gyroscopes, e-Compass etc. are some of the commonly used MEMS Sensors in cars, helicopters, aircrafts, drones and ships.

Some of the sectors of applications of MEMS based Sensors are mentioned below:

• Automotive
• Chemical and Pharmaceutical
• Aircraft
• Industrial Automation and Manufacturing
• Defense, Space and Aeronautical
• Environmental and Health Sciences
• Computing and Communications
• Consumer Products

Summary

The concept of integrating Sensors, Actuators, Electrical (and Electronic) and Mechanical devices into a single chip is considered one of the breakthrough technologies. MEMS technology will enable development of smart devices with the perception of Microsensors, control or Microactuators and computational ability of Microelectronics.

MEMS Technology is extremely diverse both in terms of its applications and areas of studies involved (Physics, Electronics, Electrical, Chemical, Material Science and Manufacturing are some of the branches involved in design and development of MEMS).