Anshul Sharma (09CE1008) D. Vishal (09CE1018) Kamalendu Ghosh (09CE1032) Suddho S. Mukherjee (09CE3006) Yogesh Narnaware (09CE3015)

Outline Introduction Manufacturing Processes Materials used Features of MEMs Applications: Transportation, automobiles etc. Advantages and Disadvantages MEMs in future Conclusion

Introduction MEMs can be defined as a combination of microsensors and/or microactuators and electronic devices on a single chip. These devices involving mechanical and electrical parts capable of acting on and sensing their environment. sensors are a crucial component in automotive electronics, medical equipment, hard disk drives, computer peripherals,wireless devices and smart portable electronics such as cell phones and PDAs.

What is MEMS? Micro-Electro-Mechanical Systems (MEMS) is a new technology that has been growing by leaps and bounds recently. MEMS is the incorporation of mechanical elements, sensors, actuators, and electronics onto a common silicon base through the use of micro fabrication technology. This technology has expanded the conventional two-dimensional design of chips; it is now possible to build three-dimensional structures into the silicon wafer. The purpose of all this is to give the ability to put an entire system onto a single chip.

As you can see in the picture above, the components are put onto a common substrate and then encased in the carrier. Below is an image of a completed accelerometer manufactured by Silcon Desigsns, Inc.componentsSilcon Desigsns, Inc. The larger rectangle on top is the microelectronics and the rectangle on the bottom is the microsensor.microelectronicsmicrosensor

MEMS Micro Electrical Mechanical Systems Practice of making and combining miniaturized mechanical and electrical components “Micromachines” in Japan “Microsystems Technology” in Europe

MEMs 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 then 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.

Components of MEMs:-

MEMS: Manufacture Process is usually a structured sequence of THREE BASIC PROCESSES: Deposition Etching lithography

Manufacturing Process DEPOSTION One of the basic building blocks in MEMS processing is the ability to deposit thin films of material with a thickness anywhere between a few nanometres to about 100 micrometres. LITHOGRAPHY Lithography in MEMS context is typically the transfer of a pattern into a photosensitive material by selective exposure to a radiation source such as light. ETCHING Etching is aimed at removing or etching away excess material from substrate.

Manufacturing

Deposition Chemical Chemical Vapour Deposition (CVD) Electro deposition Epitaxy Thermal Oxidation Physical Physical Vapour Deposition (PVD) Casting

LITHOGRAPHY Lithography is a basic micro fabrication procedure. There are several lithographic categories. Lithographyoptical Charged particle X-ray Nano- lithography

Etching Dry Wet

Etching Bulk Micromachining is aimed at removing or etching away excess material from substrate. There are two types of etching, wet and dry Dry – includes vapour phase etching and plasma phase Wet – it is achieved by exposure of the substrate to reactants like HNO3 and CH3COOH.

Materials for MEMs Silicon, glass, ceramics, polymers, and compound Group III and V elements, Metals including titanium and tungsten. Glass and fused quartz substrates, Silicon carbide and diamond Gallium Arsenide and other Group III-V semiconductors Polymers Shape memory alloys.

APPLICATIONS SENSOR ACTUATORS

Sensors MicroSensors:- The microsensors act as the arms, eyes, nose, etc. They constantly gather data from the surrounding environment and pass this information on to the microelectronics for processing. These sensors can monitor mechanical, thermal, biological, chemical, optical and magnetic readings from the surrounding environment.

Actuators MEMS often involves movable parts, making them microactuators. They can be vibrating, translating, rotating, etc., they all need a mechanical energy to move. the commonly used technics to get a movement from an object are: Thermal, Electrostatic, Magnetic, Piezoelectric and using Shape-Memory Alloys.

Thermal Actuation Asymmetric Thermal Arm Bilayer Structures

Thermal Ratcheting Actuator V-Shaped Thermal Actuators

MicroElectronics:- The microelectronics of a MEMS are very similar to chips as we think of them today. The microelectronics act as the "brain" of the system. It receives data, processes it, and makes decisions. The data received comes from the microsensors in the MEMS. MicroStructures:- Due to the increase in technology for micromachining, extremely small structrures can be built onto the surface of a chip. These tiny structures are called micro structures and are actually built right into the silicon of the MEMS. Among other things, these microstructures can be used as valves to control the flow of a substance or as very small filters. Below is a picture of a microfluidic device containing fuel filters and an exit port.

MEMS Applications: Transportation Roads would be covered with millions of MEMS sensors. The sensors would act as a blanket of information, gathering and transmitting data about road conditions. Development of windshields with automatic glare resistance. Detection of ice on roadways. Send information to vehicles equipped with Global Positioning Devices, informing the on-board computer of road hazards, accidents, and traffic. Determination of SMS and TMS and other traffic parameters

SMART PAVEMENTS Microsensors can be embedded in appropriate locations. The system consists of a retrofitted instrumented asphalt core which is bonded into the pavement structure. The core contains all information regarding temperature difference, deformations of the pavement. These microsensors are called “smart aggregates” :P

Inspection and Monitoring of Structures in Civil Engineering Sensor networks can be used to monitor a certain region of a structure providing data about different physical measures. properties to be measured Eigen-vibrations of the structure, humidity and temperature, unusual stress and strain An embedded sensor system is developed to acquire the structural condition A wireless network propagates the sensor data towards a common base station where further analysis is performed.

Scheme for wireless sensing of large structures using radio f requency transmission techniques and MEMS

MEMS Applications: Wireless. With the advent of new technology combined with the demand for more bandwidth and increased mobility, wireless applications are spreading to new markets – from radar-equipped passenger vehicles to biomedical devices that, when injected or inserted, send data to a receiver outside the body. As the wireless device market grows, so will the semiconductor products that support it.

MEMS applications: Automobiles Fuel pressure sensors, “Smart” sensors for collision avoidance and skid detection, automatic seatbelt restraint for traffic safety automatic door locking for vehicle security “Smart” suspension for sport utility vehicles to reduce rollover risk, and maintain headlight level Accelerometer and electronics are integrated on a single chip at a cost of under $10. provides a quicker response to rapid deceleration. The sensitivity of MEMs devices is also leading to improvements where size and weight of passengers will be calculated so the airbag response will be appropriate for each passenger.

Other Applications Inkjet Printers Accelerometers MEMS gyroscopes Pressure sensors Bio-MEMs Optical Switching

Automotive Market: Airbag Systems Vehicle Security Systems Intertial Brake Lights Headlight Leveling Rollover Detection Automatic Door Locks Active Suspension Consumer Market: Appliances Sports Training Devices Computer Peripherals Car and Personal Navigation Devices Active Subwoofers

Industrial Market: Earthquake Detection and Gas Shutoff Machine Health Shock and Tilt Sensing Military: Tanks Planes Equipment for Soldiers

A device embedded in a shoe’s heel can harvest energy from the compression action of walking and could power a cell phone, pacemaker or other devices. Containing a MEMS (microelectromechanical-system) device, the generator uses new voltage-regulation circuits that convert a piezoelectric charge into usable voltage for charging batteries or for directly powering electronic devices. Shoe-Powered MEMs Device Generates Energy:-

MEMs technology creates personal navigation device for defense department Guidance and navigation have been critical for military success since the dawn of civilization. Accuracy was the focus of earlier Department of Defense (DoD) navigation research, and led to the development of the Global Positioning System (GPS).

The current focus in the DoD is the development of portable localization systems, particularly for GPS-denied or - compromised environments. The primary focus of their research is applying personal navigation systems to a situation in which a soldier is dismounted. In this case, the navigation sensor is placed in the soldier’s shoe or boot sole in order to determine his or her location with high accuracy.

Shoe-based sensors

MEMS Features Low interference with environment Accurate, Compact, Shock resistant Inexpensive - based on IC batch fabrication Use in previously unfeasible domains Redundancy Large sampling size, greater data certainty

Advantages Low cost (can even be made “disposable”) They are useful in the field of defense of a nation Will work for many machine health applications Onboard signal conditioning. No charge amplifiers required.

Disadvantages Performance still below that of more expensive sensors May not be available in industrial hardened packages It is Application specific.

MEMS in Future One application still being developed is “smart dust” where MEMS sensors will be deployed in the air to measure pollution. “smart roads” where MEMS devices would be laid out as a blanket on the roadbed to measure physical conditions and traffic and report the information to geo-positioning systems mounted in cars. A lot of research into new uses for MEMS is based on military and aerospace applications. Other innovative applications include MEMS devices are also being used in optical networks and wireless communications.

CONCLUSION:- Because of the increase in micromachining technology, hundreds of MEMS can be made from a single 8-inch wafer of silicon. Below is an image which shows how small MEMS are in comparison to a dime. Because an entire system can be made this small and in such quantities, prices are reduced for products which incorporate this technology. MEMS also have no moving parts, so they are much more reliable than a macro system. Because of the reduced cost and increased reliability, there is almost no limit to what MEMS can be used for.

THANK YOU……….