Indoor formaldehyde detection and analysis

• Main Author: Tan, Ying Lin
• Other Authors: Shum Ping
• Format: Final Year Project
• Language: English
• Published: 2015
• Subjects: DRNTU::Engineering::Electrical and electronic engineering::Computer hardware, software and systems
• Online Access: http://hdl.handle.net/10356/63601
• Institution: Nanyang Technological University

Formaldehyde is a type of Volatile Organic Compounds (VOCs), which are gases with low boiling point and evaporates easily. As formaldehyde is very versatile, it had been used in many household and cleaning products that we come into contact with everyday. However, studies on formaldehyde have shown that it is linked to a higher risk of cancer and has been labeled as a Class 1 carcinogen. National Environmental Agency (NEA) has limited the indoor formaldehyde levels to 0.1 parts per million (ppm). There are many methods to determine the levels of formaldehyde vapour in the air indoors. The older conventional methods are not only bulky, expensive and require a trained operator. It led to the rise of many hand-held and wireless devices that allow users to measure formaldehyde levels at home easily. Even so, these devices are not desirable, as it do not allow autonomous operation to measure the formaldehyde levels in different corners of the room. This report focuses on creating a system with a calibrated sensor that is able to detect the presence of formaldehyde levels in real time. After which, the data that is collected can be transferred over to a central monitoring system. The project starts with the design of experiment and the circuit, followed by testing to get the calibration results. The experiments showed that the chosen DART sensor has high sensitivity and can detect dangerous formaldehyde levels even at lower range. The calibration result showed a linear relationship and can be used for further analysis of formaldehyde levels in the air. A humidity test was also conducted to ascertain the effects of humidity on the sensor. The test showed that a humid environment dissolves formaldehyde, as it is highly soluble. This reduces the amount of formaldehyde in the air. Other test conditions include a cross sensitivity test and a test for the sensor stability in different environments conducted in different rooms. It showed that different rooms with similar conditions gave similar readings, which proved the sensor’s consistency. The DART sensor also passed the cross sensitivity test and showed that it has low cross sensitivity with alcohol when there were no observable differences in the readings with and without the introduction of alcohol to the sensor.