ABSTRACT
Smart sensors are sensors with integrated electronics that can do one or move following functions:- Logic functions, two-way communication, make decisions. It consists of transduction element, signal conditioning electronic and controller or processor that supports some intelligence in a single package. This paper introduces concept of smart sensors and controllers systematically. The progress in the integrated circuits become possible because of the tremendous progress in semiconductor technology, resulted in the low cost microprocessor. By designing a low cost sensor which is silicon based the overall cost of the control system can be reduced. The usefulness of silicon technology as a smart sensor, physical phenomena of conversion to electrical output using silicon sensors, characteristics of smart sensors. The silicon sensor can produce output, as voltage, current, resistance or capacitances, output format can be analog or digital. Suitable signal conditioning circuits along with processor can easily designed using silicon technology. The presence of controller or processor in smart sensor has lead to corrections for different undesirable sensor characteristics which include input offset and span variations, non-linearity and cross sensitivity. As these are carried in software, no additional hardware is required and thus calibration becomes an electronic process. Reduced cost of bulk cables and connectors, cost improvement and remote diagnostics are the qualities of smart sensors. In this paper specifically laser based smart displaced sensor is explained, how smart sensors help anesthesiologist in Anaesthesia supervision is elaborated. An effort is made to demonstrate a prototype Sensor system. “Smart dishwasher controller”. Features of smart valve controller ends this paper.
INDEX
SR. NO. | CONTENTS |
1 | Introduction (Smart Sensors) |
2 | Usefulness of silicon technology in smart sensor |
3 | General architecture of smart sensor |
4 | Importance and Adoption of smart sensor |
5 | Laser Based Smart Displacement |
6 | Distributed smart sensor system |
7 | Application in Anaesthesia supervision |
8 | Introduction (Smart Controller) |
9 | Smart Dishwasher Controller |
10 | Smart Valve Controller |
11 | Conclusion |
12 | References |
1. INTRODUCTION: We can have integrated a sensor, which has electronics and the transduction element together on one silicon chip. This complete system can be called as system-on-chip .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. Physically a smart sensor consists of transduction element, signal conditioning electronic and controller/processor that support some intelligence in a single package. Definition: -Smart sensors are sensors with integrated electronics that can perform one or more function, a) logic functions b) two-way communication c) make decisions.
2. USEFULNESS OF SILICON TECHNOLOGY IN SMART SENSOR: There are very convincing advantages of using silicon technology in the construction of smart sensor. All integrated circuits employ silicon technology. A smart sensor is made with the same technology as integrated circuits. A smart sensor utilizes the transduction properties of one class of materials and electronic properties of silicon (GaAs). A transduction element either includes thin metal films, zinc oxide and polymeric films. Integrating electronics circuits on the sensor chip makes it possible to have single chip solution. Integrated sensors provide significant advantages in terms of overall size and the ability to use small signals from the transduction element.
Signal Conversion Effects:
Signal Domain | Examples (Measured) | Examples(Physical Effects in silicon) |
Radiant Signals | Light Intensity, polarization | Photovoltaic-effect, photoelectric effect |
Mechanical Signals | Force, pressure, flow, vaccum | Piezo-resistivity |
Thermal Signals | Temp, Temp. gradient | Seebeck effect |
Chemical Signals | Concentration, pH, toxicity | Ion sensitive field effect |
Magnetic Signals | Field intensity, flux density | Hall effect |
Different silicon sensors can be obtained by employing above effects. The silicon sensor can produce output as voltage, current, resistance or capacitance. Output format can be analog or digital. Suitable signal conditioning circuits along with processor can easily be designed using silicon technology. The presence of controller or processor in smart sensor has lead to corrections for different undesirable sensor characteristics, which include input, offset and span variations, on linearity and cross sensitivity. As these are carried out in software, no additional hardware is required and thus calibration becomes an electronic process.3. General Architecture of Smart Sensor: It is similar to a data acquisition system, the only difference being the presence of complete system on a single silicon chip. In addition to this it has on-chip offset and temperature compensation.
