Arduino Flex Sensor Circuit

If we want Arduino to feel the movement, flex sensor is best.

No click, no sound only smooth bending.

It bends and Arduino gets new value every time.

Perfect for beginners who want to control things by bending.

Simple circuit, simple code, powerful idea.

Arduino Coding:

int flex = A0;
int led1 = 4;
int led2 = 5;
int value = 0;

void setup() {
pinMode(led1, OUTPUT);
pinMode(led2, OUTPUT);
Serial.begin(9600);
}

void loop() {
value = analogRead(flex);
Serial.println(value);

if(value > 600) {
digitalWrite(led1, HIGH);
digitalWrite(led2, LOW);
} else {
digitalWrite(led1, LOW);
digitalWrite(led2, HIGH);
}
delay(100);
}

Code Explanation:

• First we set flex sensor pin as analog input.
• Two LEDs set as outputs.
• Inside loop we read sensor value.
• Serial monitor prints value.
• If value high means more bend.
• Then LED is on pin 4 turns ON.
• LED on pin 5 turns OFF.
• If value low means less bend.
• Then LED on pin 4 turns OFF.
• LED on pin 5 turns ON.
• Simple if else logic.

Circuit Working:

Parts List:

Power comes from Arduino 5V.

Flex sensor connects between 5V and analog pin A0.

A 10k resistor connects from A0 to GND.

This makes voltage divider.

Flex sensor acts like changing resistor.

When straight, resistance is low.

When bent then resistance is high.

Because resistance changes then voltage at A0 also changes.

Arduino reads this voltage as analog value 0 to 1023.

If sensor bends more then voltage becomes lower.

If sensor bends less then voltage becomes higher.

Arduino checks this value again and again in loop.

If value crosses set limit then Arduino turns one LED ON.

Other LED turns OFF.

If value goes below limit then Arduino switches LEDs again.

Formula:

Below is the voltage divider formula:

Vout = Vin * R10k / (Rflex + R10k)

where,

• Vout is the output voltage of voltage divider.
• Vin is 5V.
• Rflex is flex sensor resistance.
• R10k is 10k ohm fixed resistor.

How to Build:

To build a Arduino Flex Sensor Circuit follow the below steps for connection:

• Gather all the parts as shown in circuit diagram.
• Flex sensor has two pins.
• One pin goes to 5V.
• Other pin goes to analog pin A0.
• A 10k resistor goes from A0 to GND.
• Two LEDs are also connected.
• Green LED goes on digital pin 4 with 220 ohm resistor.
• Blue LED goes on digital pin 5 with 220 ohm resistor.
• GND from Arduino connects to all negative LED pins and bottom of 10k resistor.

Conclusion:

Flex sensor gives easy way to measure bend.

Arduino reads change and controls output.

Arduino Flex Sensor Circuit is simple and uses voltage divider.

Useful in glove projects, robotics, gesture control and DIY experiments.

Project is easy for beginners.

References:

[Beginner] Using a Flex Sensor