Electronic sensors are used to detect physical quantities and convert them into electrical current and voltage so that they can be processed using electronic circuits. Physical quantity could be anything like temperature, pressure, speed, sound, light, touch etc. Today we find electronic embedded in almost everything that we use; be it an appliance like AC, Microwave Oven etc or LED lighting or smart phones or any other modern day gadget. And since all electronic devices rely on measuring the physical quantity as a first step, sensors are becoming a vital part of our lives.

Current generation sensors are commonly known as smart or intelligent sensors. It means functionality of a smart sensor is enhanced with the adaptive use of internal data processing such as signal processor (traditionally data processing was external to the sensors and sensors were just used to convert physical quantity into electrical signal).

Smart sensors are defined by the IEEE 1451 standard in which a small amount of memory and standard physical link between the microprocessor and data network layer to provide the reliable communication is setup.

Need of Smart Sensor

In the current era the requirement is very fast processing and decision making based on the input (physical quantity), small form factor (size) of end application, reliability & robustness in handling very small signals and effective communication. All these requirements put forward the need for smart sensors because on smart sensors you have both the sensing element and processing element thus you get faster speed, smaller size and more reliability. For instance smart Micro-Electro-Mechanical Sensors (MEMS) can be used in pre-crash system to enable the consistent measurement of velocity of car and radar detects the distance of other vehicles from all sides. In case a collision is detected, control system enables the other sensor to take a best decision like reducing the vehicle speed etc.

IEEE Standards for Smart Sensors

IEEE 1451 introduced a set of standards to provide network-independent communication interface for connecting transducers (sensors) to microprocessors and other control systems or networks. IEEE defined TEDS (transducer electronic data sheets) for each and every sensor. TEDS is a memory element connected within sensor system to store information related to calibration, correction etc. The aim of IEEE 1451 is to access the sensor information through a set of interface standards with the help of wired or wireless medium. Some of the IEEE 1451 standards with their respective functionality are shown in the figure below.

Applications of Smart Sensors:

Currently, smart sensors are used in variety of applications as shown in figure 2.

Future of Smart Sensors:

• Micro-sensor implantation in patients to track the healing activities in case of internal injuries.
• Biodegradable sensors to monitor the soil moisture for effective agriculture.
• Self-healing sensors that repair themselves in case of disruption activities.
• Self-powered sensors that are powered using the heat difference between the patient bodies and surrounding air find applications in medical care.

By - Sartrajvir Singh, ECE, Chitkara University, Himachal Pradesh

References:-

1. K. Karakaya, "Smart Sensors: trends, opportunities and challenges for the future", 2012 Asia Communications and Photonics Conference (ACP), Guangzhou, 2012, pp. 1-1.
2. URL: archive.sensorsmag.com
3. Robert Johnson, Kang Lee, James Wiczer, A Standard Smart Transducer Interface - IEEE 1451, October 2001.
4. URL: http://government-2020.dupress.com/driver/sensor-technology/