How to Accurately Measure Oxygen (O2)

At Seeed, our Grove System aims to take a building block approach to assemble electronics. Initiated in 2010, Grove has since grown and has a diverse amount of sensors under its belt. Grove has many different sensors and modules ranging from temperature sensors all the way to even NFC Tags. 

Nevertheless, there is not only a variety of Grove sensors and modules to choose from, but there are also new sensors constantly introduced with improvements from the old ones. And today, we’ll be taking a look at Grove Oxygen Sensor Pro

We will be sharing about:

  • What are Oxygen Sensors?
  • About Grove Oxygen Sensor Pro
    • Specifications
    • How it works
    • Advantages
  • Project Ideas and Implementations for Grove Oxygen Sensor Pro.

What Are Oxygen Sensors?

Oxygen sensors, AKA lambda sensor, is an electronic device to measure the proportion of oxygen in the gas or liquid (if the feature is available).

Commercially, it is most commonly found in automobiles and other vehicles to measure the exhaust-gas concentration of oxygen for internal combustion engines. It will send a signal to the catalytic converter, a device that oxidizes toxic gases in exhaust gas from the engine into less-toxic pollutants, to allow it to work optimally. It will also determine whether the catalytic converter is working correctly or not. 

Source: The Vehicle Lab

A model of an automobile internal combustion engine illustrating the use of oxygen sensors

It can also be found on Divers breathing gas tank to measure the partial pressure of oxygen. Oxygen sensors are also used extensively in medical application and fire prevention systems. 

There are several ways of measuring oxygen: zirconia, electrochemical, infrared, ultrasonic, paramagnetic, and also laser methods.

About Grove – Oxygen Sensor Pro

Grove – Oxygen Sensor Pro is an electrochemical oxygen sensor. Developed by Seeed, it is a high-performance Grove gas module built with an electrochemical gas sensor inside of it, and also three electrodes and a high-performance microprocessor.

The Oxygen Sensor Pro is an enhanced version of the Grove – Oxygen Sensor. The main difference lies in the added temperature sensor in the Oxygen Sensor Pro. The temperature sensor measures the temperature of the environment to correct the measurement error caused by the temperature difference, making the measurement of oxygen significantly more accurate!

On top of that, it has a high-performance microprocessor that allows it to produce both digital and analog voltages at the same time, making the sensor easy to use and calibrate and reducing the production time.

Specifications

ItemParameter
Target GasO2
Resolution0.1%VOL
Measurement Range0-25%VOL
ReOperating VoltageDC 5±0.1V DC
Operating Current< 10 mA
OutputOutput UART(TTL electrical Level, 3V)Analog voltage(refer to table 2 for sensor original amplifying signal)
Operating Conditions-20~25℃/15~90%RH(no condensation)
Storage Conditions-20~50℃/15~90%RH(no condensation)
Sizeø23.5mm*24.5mm
Life Expectancy2 years(in the air)

How does it Work?

As mentioned, the Grove – Oxygen Sensor Pro is an Electrochemical oxygen sensor. Electrochemical oxygen sensors are primarily used to measure oxygen levels in the ambient air. This is done by the method of oxidation and reduction reactions.

These reactions in the sensors generate the positive or negative current flow through the external circuit. Gas first finds its way into the outlet of the membrane on top of the sensor housing. Then, it the aforementioned three electrodes. An electrochemical reaction (oxidation or reduction) will then occur.

Oxidation will cause the flow of electrons to move to another electrode, the counter electrode. While reduction will adversely cause the flow of electrons to move from the counter electrode to the working electrode. Essentially, the gas is going through a chemical reaction to sort them into their respective electrodes. The electron flow will create an electrical current proportional to the concentration of oxygen. 

Source: Smart Citizen

Electrochemical oxygen sensors are normally flawed by their temperature-dependent chemical processes. The reliability of the reading will be inaccurate if the temperature is not compensated. Grove – Oxygen Sensor Pro, therefore, has a built-in temperature sensor to compensate for the temperature, making the Oxygen Sensor Pro have the advantages of an electrochemical oxygen sensor without the flaws.

Advantages of Grove – Oxygen Sensor Pro

The Oxygen Sensor Pro comes with several advantages that make it an effective and reliable module.

Easy Calibration and Usage: As mentioned, the built-in high-performance microprocessor allows the Oxygen Sensor Pro to have digital output and analog voltage output capabilities, making the sensor easier to use and calibrate.

High Accuracy Readings: The built-in temperature sensor will make temperature compensation, which can correct the measurement error caused by the temperature difference and make the measurement more accurate.

Easy Connectivity: There is a built-in Grove connector and also a Grove cable given for easy connectivity to another device via the Grove system. The Grove system is a modular, standardized connector prototyping system. You may find out more about its advantages and convenience here!

Project Ideas and Implementations with Grove – Oxygen Sensor Pro

Here are a few ideas and current implementations of the Grove – Oxygen Sensor Pro. Its most commonly used for agriculture.

Seeed LoRa IoTea Solution

Source: hackster.io

Seeed IoTea was a project that Seeed initiated to collect real-time data of factors that may affect the quality of tea during cultivation and production processes, including CO2, O2, temperature, humidity and etc. The project took place at Mengding Mountain northeast of Ya’an, Sichuan. The Seeed IoTea Solution aims to assist tea farmers to better manage their plantations without altering the traditional practices of tea making and cultivation.

The project was divided into 4 main parts: Power Management, Node, Gateway and Website. Node is the main terminal of the entire system, powered by solar panels, solar charge controller and lead-acid battery. Sensors are then connected to the Node. The node transmits data to the gateway. The gateway then sends the data to the website.

Multiple sensors from the Grove eco-system was implemented including a Carbon Dioxide Sensor and an Oxygen Sensor.


This shows that Seeed’s Grove modules, including their oxygen sensors, are reliable enough to be used in professional industrial situations as well, proving its reliability. You may find out more here.

Plant Box with Lighting and Raining

Source: hackster.io

If you’re interested in agriculture or creating an automated system to take care of your plant, you’re in luck! This DIY plant bog will use sensors such as the aforementioned Grove – Oxygen Sensor Pro to detect the air and water conditions of the plant’s environment and simulate rain and lighting for the plant. It will be a fun project to learn more about the Raspberry Pis and the different sensors. 

If you’re interested, you may learn how to build on yourself here!

Summary

There are many other Grove modules that offers the same easy connectivity to devices such as Arduinos and Raspberry Pis as well. Find out more here!

We hope that you learnt more about our new Grove – Oxygen Sensor Pro. We also hope that we answered some of your queries that you might have regarding oxygen sensors. If you have any questions, feel free to leave them down in the comments below! And go here if you wish to purchase an Oxygen Sensor Pro for yourself!

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