The working principle of the universal ATP test swab is as follows:

I. The Properties and Significance of ATP

ATP (Adenosine Tri – Phosphate) is an energy – carrying molecule present in all living cells. Microorganisms such as bacteria, fungi, and viruses, as well as biological cells like human cells, animal cells, and plant cells, all require ATP to provide energy for their life activities. Therefore, the amount of ATP present on the surface of an object can reflect the degree of biological contamination of that surface and can be used as an important basis for determining its cleanliness.

II. The Structure of the Test Swab and Sampling

1. Swab Structure
   • The universal ATP test swab usually consists of a swab head and a swab stick. The swab head is generally made of a material with good adsorption properties, which can effectively collect substances containing ATP from the surface being tested. The swab stick is used for handheld operation, facilitating sampling at different locations.
2. Sampling Process
   • When the ATP test swab is used to wipe the surface of an object, the swab head will come into contact with various biological substances that may be present on the surface, including microbial cells, cell fragments, and organic residues. Since these biological substances contain ATP, the swab head will adsorb and collect them during the wiping process.

III. Chemical Reactions and Signal Generation

1. Reagent Reaction
   • In some ATP test swabs, the swab itself may contain specific test reagents, or after sampling, the swab needs to be placed in a solution containing test reagents. These test reagents are usually designed based on the principle of bioluminescence. The most common one is the luciferase – luciferin system. When the ATP collected by the swab comes into contact with luciferase and luciferin, a chemical reaction occurs.
2. Signal Generation
   • Under the catalytic action of luciferase, ATP provides energy for the oxidation of luciferin, causing luciferin to be oxidized and emit light. Specifically, the energy generated by the hydrolysis of ATP causes luciferin to change from the ground state to the excited state, and when the excited luciferin returns to the ground state, it releases photons and generates a fluorescent signal. The intensity of the generated fluorescence is directly proportional to the amount of ATP.

IV. Detection and Result Interpretation

1. Detection Method
   • After the fluorescent signal is generated, a matching ATP detector is required to measure the fluorescent signal. These detectors can accurately capture the fluorescence intensity and convert it into an electrical signal or a digital signal.
2. Result Interpretation
   • The cleanliness of the object surface is judged according to the detected fluorescence intensity. The higher the fluorescence intensity, the more ATP is collected by the swab, which means that the biological contamination of the surface being tested is more serious and the cleanliness is lower. Conversely, a lower fluorescence intensity indicates a relatively clean surface. For example, in the food processing industry, if a high fluorescence intensity is detected on the surface of production equipment, it indicates that the equipment may not be cleaned thoroughly and there is a high risk of microbial contamination, and further cleaning and disinfection are required.