diff --git a/src/MQUnifiedsensor.cpp b/src/MQUnifiedsensor.cpp
new file mode 100644
index 0000000..69f3dc1
--- /dev/null
+++ b/src/MQUnifiedsensor.cpp
@@ -0,0 +1,204 @@
+#include "MQUnifiedsensor.h"
+
+MQUnifiedsensor::MQSensor(int pin) {
+  this->_pin = pin;
+}
+
+MQUnifiedsensor::setR0(double R0) {
+  this->_R0 = R0;
+}
+
+/******************  Info of sensor graphic      *******************/
+//MQ-2 - Methane, Butane, LPG, smoke
+
+
+
+//MQ-3 - Alcohol, Ethanol, smoke
+
+
+
+//MQ-4 - Methane, CNG Gas
+
+const float R0 = 11.820;
+const float m = -0.318;
+const float b = 1.133;
+
+//MQ-5 - Natural gas, LPG
+
+
+
+//MQ-6 - LPG, butane gas
+
+
+
+//MQ-7 - Carbon Monoxide
+
+
+
+//MQ-8 - Hydrogen Gas
+
+
+
+//MQ-9 - Carbon Monoxide, flammable gasses
+
+
+
+//MQ131 - Ozone
+
+
+
+//MQ135 - Air Quality (CO, Ammonia, Benzene, Alcohol, smoke)
+
+
+
+//MQ136 - Hydrogen Sulfide gas
+
+
+
+//MQ137 - Ammonia
+   
+
+/******************  Info of sensor graphic      *******************/
+
+
+
+//***************** Operations ************************************/
+
+
+int readMethane()
+{
+
+}
+int readButane()
+{
+
+}
+int readLPG()
+{
+
+}
+int readSmoke()
+{
+
+}
+int readAlcohol()
+{
+
+}
+int readEthanol()
+{
+
+}
+int readCNG()
+{
+
+}
+int readLPG()
+{
+
+}
+int readCO()
+{
+
+}
+int readHO()
+{
+
+}
+int readCarbonMonoxide()
+{
+    
+}
+int readNH4()
+{
+    
+}
+int readbenzene()
+{
+    
+}
+int readAlcohol()
+{
+    
+}
+int readHidrogen()
+{
+    
+}
+int readToluene()
+{
+    
+}
+int readAcetone()
+{
+    
+}
+int readPropane()
+{
+    
+}
+int readCoalGas()
+{
+    
+}
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+const float VOLT_RESOLUTION = 5.0; // if 3.3v use 3.3
+const int ADC_RESOLUTION = 10; // for 10bit analog to digital converter.
+
+const int retries = 50;
+const int retry_interval = 20;
+
+double MQUnifiedsensor::calibrate() {
+    float sensor_volt; //Define variable for sensor voltage
+    float RS_air; //Define variable for sensor resistance
+    float R0; //Define variable for R0
+    float sensorValue; //Define variable for analog readings
+    sensor_volt = this->getVoltage(); //Convert average to voltage
+    RS_air = ((5.0 * 10.0) / sensor_volt) - 10.0; //Calculate RS in fresh air
+    R0 = RS_air / 4.4; //Calculate R0
+    return R0;
+}
+
+double MQUnifiedsensor::getVoltage() {
+  double avg = 0.0;
+  for (int i = 0; i < retries; i ++) {
+    avg += analogRead(this->_pin) / retries;
+    delay(retry_interval);
+  }
+
+  double voltage = avg * VOLT_RESOLUTION / (pow(2, ADC_RESOLUTION) - 1);
+
+  return voltage;
+}
+  
+  /**
+    * Returns the PPM concentration
+    */
+  int MQUnifiedsensor::read() {
+    double sensor_volt = this->getVoltage();
+    double RS_gas; //Define variable for sensor resistance
+    double ratio; //Define variable for ratio
+
+    RS_gas = ((5.0 * 10.0) / sensor_volt) - 10.0; //Get value of RS in a gas
+
+    ratio = RS_gas / this->_R0;   // Get ratio RS_gas/RS_air
+
+    double ppm_log = (log10(ratio) - b) / m; //Get ppm value in linear scale according to the the ratio value
+    double ppm = pow(10, ppm_log); //Convert ppm value to log scale
+    return floor(ppm);
+}
\ No newline at end of file
diff --git a/src/MQUnifiedsensor.h b/src/MQUnifiedsensor.h
new file mode 100644
index 0000000..eda452c
--- /dev/null
+++ b/src/MQUnifiedsensor.h
@@ -0,0 +1,68 @@
+#ifndef MQUnifiedsensor_H
+#define MQUnifiedsensor_H
+
+#include <Arduino.h>
+
+class MQUnifiedsensor
+{
+  public:
+    /**
+     * Constructor
+     */
+    MQSensor(int pin);
+    setR0(double R0);
+    setSensorTyp(int sensorNumber);
+    /**
+     * Returns the PPM concentration    
+    MQ-2 - Methane, Butane, LPG, smoke
+    MQ-3 - Alcohol, Ethanol, smoke
+    MQ-4 - Methane, CNG Gas
+    MQ-5 - Natural gas, LPG
+    MQ-6 - LPG, butane gas
+    MQ-7 - Carbon Monoxide
+    MQ-8 - Hydrogen Gas
+    MQ-9 - Carbon Monoxide, flammable gasses
+    MQ131 - Ozone
+    MQ135 - Air Quality (CO, Ammonia, Benzene, Alcohol, smoke)
+    MQ136 - Hydrogen Sulfide gas
+    MQ137 - Ammonia
+    MQ138 - Benzene, Toluene, Alcohol, Acetone, Propane, Formaldehyde gas, Hydrogen
+    */
+
+    int readMethane();
+    int readButane();
+    int readLPG();
+    int readSmoke();
+    int readAlcohol();
+    int readEthanol();
+    int readCNG();
+    int readLPG();
+    int readCO();
+    int readHO();
+    int readCarbonMonoxide();
+    int readNH4();
+    int readbenzene();
+    int readAlcohol();
+    int readHidrogen();
+    int readToluene();
+    int readAcetone();
+    int readPropane();
+    int readCoalGas();
+
+
+    /**
+     * Calibrates the start point of 400
+     */    
+    double calibrate();
+
+    /**
+     * Returns the voltage
+     */
+    double getVoltage();
+    
+  private:
+    int _pin;
+    double _R0;
+};
+
+#endif //MQUnifiedsensor_H
\ No newline at end of file