 Flex Sensor and Arduino Simulation in Proteus
In this post I will discuss about the flex sensor, applications of the Flex sensor, interfacing of the flex sensor with the Arduino microcontroller development board. In the previous post I have discussed the Ultrasonic sensor and its simulation in the Proteus.
After reading this post you will be able to learn the simulation of flex sensor in the Proteus and you will also learn about the Interfacing of the Arduino with the Flex sensor. So sit back, keep reading and enjoy learning.

#### what is Flex Sensor:

Before diving deep into the discussion on the simulation of the flex sensor in the Proteus let us first learn what the flex sensor is and how it works. The flex sensor like most of the sensors measures the physical quantity but do so in the unique way. The flex sensor measures the amount of stress that is applied on the sensor while it is being bent that is when the flex sensor is made to bent the resistive film present inside the flex changes its resistance due to the mechanical stress that is applied to it while being bent. The more the sensor is bent the more will be change in resistance. So you can say that flex sensor measures the amount of force or bending angle by exploiting the change in its resistance. The flex sensor looks like the one in the following figure: Notice in the above figure that the Flex sensor has only two pins. You can alternately connect the each pin to either voltage supply or ground. It is not a rule of thumb to connect the pins as shown in the figure above:

#### Working of the Flex Sensor:

Let us now see how the Flex sensor can be used in the circuit. As we have learned in the previous discussion that the Flex sensor measures the bending or the stress applied in that way by altering its resistance correspondingly. So we can say that the Flex sensor is basically the variable resistor whose resistance depends upon the amount of bend. Also notice that the Flex sensor is the analog sensor so in order to measure the change in resistance corresponding to the amount that the flex sensor is bent, we need a simple voltage divider circuit. The circuit for reading the change in voltage as a result of the change in resistance is shown in the figure below: [/vc_column_text][/vc_column][/vc_row]

Now let us understand the working of the above circuit. As can be seen in the figure that the Flex sensor is connected to the 1 kilo ohm resistor in voltage divider configuration. So if the resistance of the Flex sensor varies with the amount of the bending the voltage drop as governed by the voltage divider equation varies across the 1 kilo resistor and the flex sensor itself. The variation of the voltage level can then easily be read on the analog pin of the Arduino microcontroller development board. So this is the way the flex sensor works.

#### Applications of the Flex sensor:

Once you have learned the principle of the working of the any sensor you can use it any way you want. The most common application of the Flex sensor is in the Robotic hand where five Flex sensors with their voltage divider circuits are connected to the Arduino microcontroller development board.

#### Flex Sensor Simulation in Proteus:

Let us now see the working of the Flex Sensor in the Proteus. For this you must have the simulation model of the Flex sensor in the library of the Proteus. The importance of the simulation model and the Ultrasonic sensor simulation is discussed in my previous post. Go through that post it is worth reading. In order to simulate the behavior of the Flex sensor in Proteus follow the following simple steps.

##### Step 1:

The simulation model of the Flex sensor is not installed in the library of the Proteus by default so you need to download it first and place it in the library of the Proteus. The method of placing the simulation model files in the library of the Proteus is already discussed in the post on Ultrasonic sensor so go through that post if you do not know how to place the simulation model files in the library of the Proteus. After placing the files restart your Proteus.

##### Step 2:

Now search for the Flex sensor in the Proteus library as shown in the following figure: ##### Step 3:

Now look for the 1 kilo ohm resistor and place the components in the workspace. Draw the circuit as shown in the following figure: As shown in the circuit above that the circuit is designed in such a way to assess the output voltage corresponding to the signal applied at the input of the Flex sensor. Notice that the digital logic toggle is used in this case and also the output is taken from the third terminal which is not present in the actual Flex sensor. So the reason for this is that the flex sensor simulation model is in progress of designing and here is just the approximate model. When the toggle is pushed high or low the corresponding voltage level would be read on the voltmeter.

The whole process is shown in the following video.
That is all for now. In the next post I will come up with more interesting topics and applications of the Proteus. Till then stay blessed, keep reading and enjoy learning.