Grove - Alcohol Sensor is a complete alcohol sensor module for Arduino or Seeeduino. It is built with MQ303A semiconductor alcohol sensor. It has good sensitivity and fast response to alcohol. It is suitable for making Breathalyzer. This Grove implements all the necessary circuitry for MQ303A like power conditioning and heater power supply. This sensor outputs a voltage inversely proportional to the alcohol concentration in air.
Model:SEN21723P
Note that The sensor value only reflects the approximated trend of gas concentration in a permissible error range, it DOES NOT represent the exact gas concentration. The detection of certain components in the air usually requires a more precise and costly instrument, which cannot be done with a single gas sensor. If your project is aimed at obtaining the gas concentration at a very precise level, then we do not recommend this gas sensor.
Grove products have a eco system and all have a same connector which can plug onto the Base Shield. Connect this module to the A0 port of Base Shield, however, you can also connect Gas sensor to Arduino without Base Shield by jumper wires.
| Arduino UNO | Alcohol Sensor |
|---|---|
| 5V | VCC |
| GND | GND |
| Analog A1 | SCL |
| Analog A0 | DAT |
You can gain the present voltage through the DAT pin of sensor. Sensitivity can be regulated by rotating the potentiometer.
Please note the best preheat time of the sensor is above 48 hours. For the detailed information about the Alcohol sensor please refer to the datasheet.
First, connect the module with Grove Shield using A0 like the picture above. And put the sensor in a clear air and use the program below.
#define heaterSelPin 15 void setup() { Serial.begin(9600); pinMode(heaterSelPin,OUTPUT); // set the heaterSelPin as digital output. digitalWrite(heaterSelPin,LOW); // Start to heat the sensor } void loop() { float sensor_volt; float RS_air; // Get the value of RS via in a clear air float sensorValue; /*--- Get a average data by testing 100 times ---*/ for(int x = 0 ; x < 100 ; x++) { sensorValue = sensorValue + analogRead(A0); } sensorValue = sensorValue/100.0; /*-----------------------------------------------*/ sensor_volt = sensorValue/1024*5.0; RS_air = sensor_volt/(5.0-sensor_volt); // omit *R16 Serial.print("sensor_volt = "); Serial.print(sensor_volt); Serial.println("V"); Serial.print("RS_air = "); Serial.println(RS_air); delay(1000); }
Then, open the monitor of Arduino IDE, you can see some data are printed, write down the value of RS_air and you need to use it in the following program. During this step, you may pay a while time to test the value of RS_air.
#define heaterSelPin 15 void setup() { Serial.begin(9600); pinMode(heaterSelPin,OUTPUT); // set the heaterSelPin as digital output. digitalWrite(heaterSelPin,LOW); // Start to heat the sensor } void loop() { float sensor_volt; float RS_gas; // Get value of RS in a GAS float ratio; // Get ratio RS_GAS/RS_air int sensorValue = analogRead(A0); sensor_volt=(float)sensorValue/1024*5.0; RS_gas = sensor_volt/5.0-sensor_volt; // omit *R16 /*-Replace the name "R0" with the value of R0 in the demo of First Test -*/ ratio = RS_gas/RS_air; // ratio = RS/R0 /*-----------------------------------------------------------------------*/ Serial.print("sensor_volt = "); Serial.println(sensor_volt); Serial.print("RS_ratio = "); Serial.println(RS_gas); Serial.print("Rs/R0 = "); Serial.println(ratio); Serial.print("\n\n"); delay(1000); }
Now, we can get the concentration of gas from the below figure
According to the figure, we can see that the minimum concentration we can test is 20ppm and the maximum is 10000ppm, in a other word, we can get a concentration of gas between 0.002% and 1%. However, we can't provide a formula because the relation between ratio and concentration is nonlinear.