Censorship is something that is used to detect changes in the physical or chemical environment. The variable output of the sensor is converted into electrical quantities are called transducers. At this time, the sensor has been created by the very small size of the order of nanometers. A very small size is very convenient use and save energy.
Classification of the sensor are:
– Chemical Sensor
– Sensor Physics
– Biological Sensors
a. chemical sensors
Chemical sensors detect the amount of a chemical substance by altering the amount of chemical into electrical quantities. Typically involves several chemical reactions. Examples of chemical sensor is a pH sensor, oxygen sensor, explosion sensors, and gas sensors.
b. sensor Physics
In general, based on the functions and use of sensors can be grouped into 3 parts:
a. sensor thermal (heat)
b. mechanical sensor
c. optical sensors (light)
Thermal sensor is a sensor used to detect the symptoms of heat changes / temperature / temperature on a dimensional objects or tertentu.Contohnya dimensional space; bimetal, thermistors, thermocouples, RTD, photo transistors, photo diodes, photo multiplier, photovoltaic, infrared pyrometer, hygrometer, etc.
Mechanical sensor is a sensor that detects changes in mechanical motion, such as displacement or shift or position, straight and circular motion, pressure, flow, level dsb.Contoh; strain gage, linear variable deferential transformer (LVDT), proximity, potentiometers, load cell, Bourdon tube, etc.
Optical or light sensor is a sensor that detects changes in light from the light source, the light reflection or refraction of light that mengernai objects or space.
Example; photo cell, photo transistors, photo diodes, photo voltaic, photo multiplier, optical pyrometer, etc.
Physics sensor detects the magnitude of a quantity based on the laws of physics. Examples sensos physics are light sensors, sound sensors, force sensors, pressure sensors, vibration sensors / vibration, motion sensor, speed sensor, acceleration sensor, gravity sensor, temperature sensor, humidity sensor, the electric field sensor / magnetic, dl
c. Biological sensors
– sensor measurement of molecules and biomolecules: detoxification, nutrient, pheromone
– sensor measuring glucose levels, oxigen, and osmolitas
– sensor measurement of proteins and hormones
So the amount of electricity where it is involved in some chemical reactions, such as for example the pH sensor, an oxygen sensor, explosion sensors, and gas sensors. Prior to understand and implement the use of sensors in detail it is necessary to study the nature and classification of the sensor in general. The sensor is electrical or electronic components, where the nature or character of the electrical acquired or taken through electrical quantities (eg, electric current, power voltage can also be obtained from non-electrical quantities, eg force, pressure that has massive mechanical, or temperature is massive thermic, and can also be chemically magnitude, it may even be the amount of optical).
Sensor distinguished according to the activity sensor based on the conversion of the signal do not signal the amount of electricity (non electric signal value) to the amount of electrical signal (electric signal value), namely: active sensor (active sensor) and passive sensors (passive sensors). The following figure 3.1 Nature of sensors based on classification according to its function.
Figure 3.1. The nature of the sensor based classification
Active Sensor (active sensor)
Active sensor is a sensor that can turn right out of energy that has non-electrical quantities (such as mechanical energy, thermal energy, light energy or chemical energy) into electrical energy quantities. These sensors are usually packaged in a single package consisting of the sensor element as a detector, and a converter device as a transducer of energy with non-electrical quantities into electrical quantities of energy.
Sensors are classified as active sensors have many kinds and types sold in the market of electronic components (for example: thermocouple, photo cell or frequently on the market LDR “Light Dependent Resistor”, the photo diode, piezo electric, photo transistors, elements of solar cell, tacho generators, and others). The working principle of this type of active sensors is to produce a change in resistance / electrical resistance, voltage changes or also direct electric current when given a response obstructions or response enhancer on the sensor (eg light / light toward the sensors obstructed or plus light, heat on the sensor is reduced or plus and others).