Formaldehyde sensors are devices that can detect and measure the concentration of formaldehyde gas in the air. Formaldehyde is a colourless, flammable, and corrosive gas that is widely used in various industries and household products, such as building materials, paper coatings, cosmetics, and disinfectants. Formaldehyde exposure can cause adverse health effects, such as headaches, breathing difficulties, and cancer. Therefore, it is important to monitor the formaldehyde levels in indoor and outdoor environments to ensure safety and compliance with regulations.

There are different types of formaldehyde sensors based on different principles, such as electrochemical, optical, and photochemical sensors. Electrochemical sensors are simple and low-cost devices that produce a small electric current when formaldehyde gas diffuses into the sensor. Optical sensors use localized surface plasmon resonance (LSPR) to detect changes in the local dielectric environment caused by formaldehyde gas adsorption on the sensor surface. Photochemical sensors use a chemical reaction between formaldehyde and a reagent to produce a colour change that can be measured by a smartphone camera.

Each type of formaldehyde sensor has its own advantages and disadvantages in terms of sensitivity, selectivity, response time, stability, and power consumption. The choice of the best formaldehyde sensor depends on the specific application and requirements of the user.