Sensors have been a favorite topic among the designers and researchers all over the world. Lots of noise has been created around IoTs (Internet Of Things), and some genuine products have also come up in the market as of result of its rise. IoT is nothing without sensors specifically miniature sensors and not those traditional bulky ones which are difficult to install and use by a general consumer. In context to India where concept of smart city are being discussed and proposed, the requirement of efficient, low cost and small form factor Sensors are the need of hour. With the growing speed in technology specially electronics, circuits are getting smaller and smaller and are getting clubbed into a small chip. Though the number of transistors are increasing exponentially but the reduction in size are far from comparison with the traditional devices.
In this article, different sensor technologies being used and researched are explored and discussed along with their applications. The article is divided into sections as per its area of applications.
Sensors In Home
Home automation has been explored a lot in past few years and many products like automatic light control, fan control, Burglar alarms, Fire alarms etc has been already been converted to a full fledged and tested product. However, there are number of sensors added into the system which has to be installed inside home. General sensors which has been explored in the market include Infra Red, Ultra Sonic Sensors for presence or absence of any object to perform actions like burglar alarm, automatic light control, fan control or rather entire electricity of the house. The sensors presently available are all distributed. Recently there were developments where creators designed an android controlled bulbs. Even Phillips have come up with such product where in the bulb would behave as per the surrounding. When there is a disco like environment, the bulb blink resonates with music, its intensity can be controlled with Bluetooth etc.
One of the recent product in research is the adaptable fan speed control for home automation using an android smart phone. The system is designed to be automatic as well as manual. There is temperature sensor LM35 attached to the system which continuously gives feedback of temperature to the microcontroller. Here user can set in ones Smartphone the required fan speed for different temperature as per his needs and simply press on the system. The system would automatically respond as per his speed request as the temperature changes. In the another scenario let us take for example a situation in a place like Mumbai where morning gets bit cold and nights are hotter in summer. We are sleeping and we don’t want to wake up to change the speed of the fan. In such situation this application comes handy where in we can simply write the required speed variation with respect to time in our android application and go to sleep. The system would respond to our request and would maintain the temperature of the room as per our request. Such type of sensor based wireless applications are the next generation consumer electronics.
Figure 1 shows the block diagram of how this system can be implemented.
Sensors In Medical Applications
Medical Electronics has seen lots of new inventions for detection of deadly diseases, operations and even treatment. Sensor technology specially the new area of Bio-Mems and Biosensors based devices have revolutionized the medical industry. Bio-Mems are the chips which has mechanical elements embedded within the chip and can be used for multiple medical applications. BioMems devices have already been deployed into the field of heart attack detection, Blood Glucose check instruments, alcohol detection. Some more of the Biosensor applications include cholesterol testing, infectious disease testing, Blood gas testing, Pregnancy testing, cancer biomarkers, tumor markers, urinalysis. According to the new market report published by Persistence Market Research “Global Market Study on BioSensor : Asia-Pacific is to witness highest growth by 2020”, the global biosensor market was valued at USD 12,963.6 million in 2014 and is expected to grow at a CAGR of 9.7% from 2014 to 2020, to reach an estimated value of USD 22,551.2 million in 2020. “
Figure 2 shows the block diagram of the Bio-Mems sensor. The analyte is the material to test eg blood. The selective layer separates the blood with the content of chemicals to test. The chemical then behaves in a certain manner to bring some mechanical action which is converted to electrical signal using transducer for further actions. The signal is further processed using controller and displayed or actuated for various applications.
Figure 2: Block Diagram of BioMem Sensor
Figure 3 shows the microscopic view of the microneedle inside an IC which are used in many bio sensor applications eg for blood glucose testing. Figure 4 shows the microscopic view of BioMems acceleratometer using in mobiles and medical applications.
Figure 3: Micro needles Embedded in a chip
Figure 4: Mems Acceleratometer Microscopic IC Image
Some other application in the medical and environmental fields include food toxicity detection, agricultural detection, industrial process testing etc.
Sensors In Civil Engineering
With the advent of industrial revolution huge structures like bridges, tunnels, buildings, power houses, dams etc are being constructed in enormous number. With increase in technological advancements there has been equal increase in number of disasters happening due to failure of these structures. The disaster starts with a small crack which may even not be visible with naked eyes. An attempt has been made to track the health of these structures with respect to temperature, strain, vibration etc so as to detect the cracks at early stage.
There are many sensors available which are used in many places but these sensors are very large in number hence monitoring all the sensors with equal efficiency is a challenging job.
Hence state of the art technology in optic fibers using OFDR has been proposed and implemented by many researchers to implement distributed type of sensing mechanism which would provide high efficiency in terms of the early detection of any type of changes in structures along with reducing the problem of placing huge number of sensors in various locations. Therefore single length optic fiber with various properties has been explored in order to suit for the best performance in distributed sensing. Due to effort of engineers and researchers in optic fiber community the large area coverage of the sensor with very accurate sensing capabilities have been developed.
