Smart sensors and their Application

A SEMINAR PPT ON SMART SENSORS AND THEIR APPLICATIONS

1. A Seminar on “ SMART SENSORS AND THEIR APPLICATIONS ” Guided By Submitted By Dr. Piyush N. Patel Yash Kant Verma Assistant Professor U11EC011 ECED, SVNIT, SURAT ECED, SVNIT, SURAT

2. CONTENTS INTRODUCTION ARCHITECTURE FABRICATION ADVANTAGES AND DISADVANTAGES APPLICATIONS SUMMARY REFERENCES

3. 1. INTRODUCTION Sensors are devices that responds to a physical stimulus heat, light, sound, pressure, magnetism, motion, etc , and convert that into an electrical signal. They perform an input function. Devices which perform an output function are generally called Actuators and are used to control some external device, for example movement. Both sensors and actuators are collectively known as Transducers . Transducers are devices used to convert energy of one kind into energy of another kind.

4. SMART SENSOR A smart sensor is an analog /digital transducer combined with a processing unit and a communication interface. It consists of transduction element, signal conditioning electronic and controller/processor that support some intelligence in a single package. This integrated sensors which has electronics and the transduction element together on one silicon chip, this system can be called as system-on-chip ( SoC ).The main aim of integrating the electronics and the sensor is to make an intelligent sensor, which can be called as smart sensor. Smart sensors then have the ability to make some decision.

5. Smart sensors / Intelligent sensor are sensors with integrated electronics that can perform one or more of the following function:[1] 1. Data Conversion 2. Bidirectional communication 3. Take decisions 4. Perform logical operations

6. TYPES OF SMART SENSORS SMART SENSOR HYBRID Three different types of configurations are shown in which all the components are placed on a chip. This is called standardization. In the first hybrid system, a sensor is connected with ADC and bus interface with the help of universal sensor interface. The second configuration shows the connection of sensor analog system with the digital circuit and bus interface. In the third configuration, sensor is combined with the interface circuit already to provide duty cycle and bit stream as shown in figure

7. INTEGRATED SMART SENSORS If we integrate all functions from sensor to bus interface in one chip, we get an integrated smart sensor as shown in figure below.[1]

8. SMART SENSOR NETWORK A sensor network is a collection of sensors interconnected with each other by a communication network. A sensor network is made up of individual multifunctional sensor nodes. It has much significance like sensing accuracy, area coverage, connectivity, minimal human interaction. Figure below shows the elements of a single network node.

9. 2. SMART SENSOR ARCHITECTURE The basic architectural components of smart sensor are listed as follows: Sensing element/transduction element , Amplifier, Sample and hold, Analog multiplexer, Analog to digital converter (ADC), Offset and temperature compensation , Digital to analog converter (DAC), Memory, Serial communication Processor

10. Five main parts of sensor node are: The central unit: It is in the form of microprocessor which manages the tasks. Battery: Is the source of energy A Transceiver: Interacts with the environment and collects data. Memory: Used as storage media for storing data or processing data. Communication module: It includes transceivers and forwards queries and data to and from central module. [2]

11. Signal Processing The signals recorded by many sensors are typically low in amplitude, Integration of interface electronics and signal processing circuitry at the sensor site (monolithic or hybrid) serves a number of functions, including signal amplification, impedance transformation, signal filtering and buffering, and multiplexing. CMOS amplifiers are perhaps the most suitable since they provide high gain and high input impedance through a relatively simple and compact circuit and are readily compatible with integration of high-density digital circuitry on the same chip. In addition to signal amplification, impedance transformation and signal filtering are also required.

12. Digital Processing and Manipulation The main circuit block required before digital control and manipulation of sensor data can take place is the analog -digital converter. Once the sensor data is digitized, a variety of signal processing schemes can be used to correct for a number of errors and shortcomings. These include offset cancellation, auto-calibration, self-testing, fault detection and correction and linearity correction. Auto-calibration is a very desirable function for smart sensors. Most sensors should be adjusted for changes in gain and offset. Reliability and accuracy.

13. Communication and Bus Interaction A smart sensor should be capable of interacting with a higher level controller that manages the overall system . Efforts are currently underway to develop such a standard bus for sensor applications that is uniquely designed to optimize functionality, speed and overall cost. A variety of information can be exchanged between the sensor and the controller over the bus, including calibration and compensation data, addresses and personality information, measured data, and programming data initiated by the controller, the communication interface should have the ability to receive and transmit information over the bus at a fairly high speed it should be noted that many sensor signals have limited bandwidth and even in the case of a multi-sensor system, the bus data rate may be sufficient to accommodate all sensors [2]

14. 3. FABRICATION Sensor is made with the same technology as integrated circuit. A smart sensor utilizes the transduction properties of one class of materials and electronic properties of silicon ( GaAs ) One problem with silicon is that its sensitivities to strain, light and magnetic field show a large cross-sensitivity to temperature. When it is not possible to have silicon with proper effects, it is possible to deposit layers of materials with desired sensitivity on the top of a silicon substrate.

15. Solid- State integrated sensors are basically composed of four elements namely, custom films for transduction, microstructures, integrated interface circuitry and microcomputer based signal processing algorithms. Mainly, three techniques bulk micro-machining, surface micromachining and wafer bonding process are used for fabrication of smart sensors Fig showing the fabrication of a pressure sensor[3]

16. 4. ADVANTAGES AND DISADVANTAGES ADVANTAGES[4] The smart sensor takes over the conditioning and control of the sensor signal, reducing the load on the central control system, allowing faster system operation. Direct digital control provides high accuracy, not achievable with analog control systems and central processing . The cost of smart sensor systems is presently higher than that of conventional systems, but when the cost of maintenance, ease of programming, ease of adding new sensors is taken into account, the long- term cost of smart sensor systems is less. Individual controllers can monitor and control more than one process variable.

17. DISADVANTAGES If upgrading to smart sensors, care has to be taken when mixing old devices with new sensors, since they may not be compatible. If a bus wire fails, the total system is down, which is not the case with discrete wiring. However, with discrete wiring, if one sensor connection fails, it may be necessary to shut the system down. The problem of bus wire failure can be alleviated by the use of a redundant backup bus.

18. 5. APPLICATIONS INDUSTRIAL In industries machines and equipments are monitored and controlled for pressure, temperature , humidity level and also for vibrations AUTOMOTIVES Communications between engine, transmission, suspension, braking and other controls has long been anticipated. FINGER PRINT RECOGNISITION A fingerprint sensor is an electronic device used to capture a digital image of the fingerprint pattern. The captured image is called a live scan. This live scan is digitally processed to create a biometric template (a collection of extracted features) which is stored and used for matching .

19. PATTERN RECOGNISITION The sensor uses incident light or backlight to detect the contours of an object and compares them with the contours of one or several models in a reference image . TELECOMMUNICATION A smart card known as a Wireless Identity Module, is similar to the Subscriber Identity Module (SIM) used on existing GSM cellular phones. The card guarantees 100-percent security for e-commerce transactions by providing authentication of the parties involved, by means of encryption and digital signatures.[5]

20. SMART TOYS These days the trend in toys is to make them as life-like as possible which move or change directions after sensing objects around them . SMART DUST: Smart dust is a hypothetical wireless network of tiny micro-electro-mechanical (MEMS) sensors, robots, or devices, which can detect (for example) light, temperature, or vibration. The devices will eventually be the size of a grain of sand, or even a dust particle, with each mote having self-contained sensing, computation, communication and power.[6]

21. BIOMEDICAL APPLICATIONS A number of smart sensors for biomedical applications have also been developed by using chip technology .e.g. biochips Cyto -sensor micro- physio -meter: biological applications of silicon technology. MEMS AND PROCESS CONTROL MEMS (Micro-Electro-Mechanical Systems) is a class of systems that are physically small. These systems have both electrical and mechanical components. MEMS originally used modified integrated circuit (computer chip) fabrication techniques and materials to create these very small mechanical devices

22. DEFENCE APPLICATIONS Smart cameras that can operate sophisticated software analytics onboard the camera itself, and then report alarms remotely using IP networking facilities. It has ability to perform object detection, crowd pattern analysis, secure zone intrusion detection, and so on boost the efficiency and accuracy of a human operator who is likely monitoring multiple banks of displays. Smart sensor equipments helps in monitoring a wide variety of parameters like EMI, fatigue loading, thermal cycling, vibration and shock levels, acoustic emissions and corrosive environments

23. 6. SUMMARY Automization can’t be imagined without the smart sensors. These sensors are potentially cheaper, offer higher performance and reliability, and are much smaller in size than their discrete counterparts. They have also been employed in applications including transportation and health care and in large part have fulfilled their promise. Sensor signals can be amplified and properly processed, are multiplexed and are buffered ready to be received by micro-processor on these signals and offer a standard data stream to the user thus making the entire sensing module behave like a system periphery rather than a passive component.

24. REFERENCES Frank. R; “Understanding the Smart Sensors”; Artech House; Second edition; Page 1-5; 2000 Nitaigour P. Mahalik : Sensor Networks and Configuration. Fundamentals, Standards, Platforms and Applications. Springer Verlag Berlin, english , 1st ed. November 2006, ISBN 3-540-37364-0, ISBN 978-3-540-37364-3 Borky J M and Wise K D 1979 Integrated signal conditioning for silicon pressure sensors IEEE Trans. on Electron Devices ED-26 1906-10 M. Bowen, G. Smith, “Considerations for the design of smart sensors,” Sensors and Actuators, A 46- 47(1995) 516-520. S. Middelhoer and A.C. Hoogerwerf , “Smart sensors when and where,” Sensors and Actuators, 8(1985) 39-48. http://www.smartsensortechnologies.com/fs-system.html [Retrieved on 11-11-2014]

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