Luminometer, Principle, Types

Introduction?

It is an instrument that measures the faint emission of visible light emitted from a sample using a photomultiplier tube. In order to measure extremely small amounts of light, often just a few photons, luminometers are highly sensitive instruments.

Working:

It works on the principles of the photoelectric effect and signal amplification using a photomultiplier tube (PMT). Here's a step-by-step explanation of how a luminometer works:

Sample preparation: The sample to be measured is usually a small volume, such as a protein solution or cell suspension in a microcentrifuge tube or microplate wells.

Photomultiplier (PMT): The most important part of the luminometer is the PMT, which detects and amplifies the light signals emitted by the sample. The PMT consists of several stages, including a photocathode, dynodes, and an anode.

Photon Detection: When photons from a sample hit the photocathode, they cause electrons to be emitted by the photoelectric effect. 

Electronic Amplification: The emitted electrons are accelerated by a high voltage field and undergo a process called secondary emission in the dynodes. In this process, each electron that reaches the dynode produces several new electrons, resulting in a significant amplification of the original signal.

Output Signal: The amplified electrons finally reach the anode, which is connected to the luminometer's output processing circuit. The circuit converts the electronic signal into an output signal, which can be in the form of pulses (photon counting mode) or analog current (analog or current mode).

Signal Processing: The PMT output signal is further processed to provide meaningful readings. In photon counting mode, pulses are counted to determine the number of photons detected. In analog mode, the current signal is measured and converted into the corresponding light intensity value.

Other important components of a luminometer are:

Darkroom: The measuring area of the luminometer must be completely shielded from external light to avoid interference. It must also be sized to match the type of sample container used, such as vials or microplate wells.

Injectors: Some tests require the addition of reagents to the sample to initiate a chemical reaction based on luminescence or fluorescence. Injectors can be incorporated into the luminometer for precise control of reagent addition time or in cases where the reaction is very fast.

Filters or Monochromators: While most luminometers measure all wavelengths of light together, some tests, such as BRET (Bioluminescent Resonance Energy Transfer), may require the use of filters or monochromators to separate and analyze the light emitted by different proteins in a sample. to be measured based on their specific wavelengths.

In general, the luminometer combines the light-sensing ability of a photomultiplier tube with signal processing and control functions to accurately measure and quantify the light emitted by a sample, making it suitable for use in various fields of biotechnology, biochemistry, and science. molecular biology.

Types:

Several types of luminometers are available, each designed for specific applications and detection methods. Here are some common types:

Single Tube: This is the simplest type of luminometer, usually used for single sample measurements. It consists of a photomultiplier or photodiode detector and a sample chamber in which the light emission is recorded. Single-tube luminometers are commonly used in basic research and routine laboratory research.

Microplate: It is designed to measure the light output of multiple samples simultaneously. It is compatible with microplates containing multiple sample wells. Often equipped with automated plate handling systems, these luminometers are widely used in high-throughput screening, enzymatic analysis, and other applications that require high-volume sample processing.

Imaging Luminometer: They combine the capabilities of a luminometer with a high-resolution camera. They capture images of the light emitted by the sample, allowing spatial and temporal analysis of the light output. Imaging luminometers are particularly useful for studying cellular and tissue luminescence, such as bioluminescent imaging in live animals or luminescent reporter assays in cell cultures.

Portable Luminometer:  Portable luminometers are compact, battery-powered devices designed for measurement in the field or on-site. They are often used in environmental monitoring, food safety testing, and other applications where portability and ease of use are important.

Dual Function Luminometer: Some advanced luminometers combine the capabilities of a luminometer with other detection methods, such as fluorescence or absorption. These dual-purpose tools provide researchers with greater versatility and flexibility in designing experiments and collecting data.

The luminometer plays a crucial role in the ATP testing procedure. Hygiena's EnSURE Touch and SystemSURE Plus have luminometers as part of their design and are two of the best-selling ATP hygiene monitors on the market. At Sychem, we are experts in the infection control category and can advise our customers on the best ATP tests and devices for their facility.

How does it Work?

A luminometer is the name given to a tabletop or portable instrument used to measure the faint emission of visible light produced by a sample. Hygiena luminometers, when used with ATP buffers, use bioluminescence to detect residual ATP as an indicator of surface cleanliness. The presence of ATP on the surface indicates that cleaning has not been done properly, as does contamination, including food debris, allergens, and/or bacteria. Therefore, there is a possibility of bacteria growing on the surface. Hygiena's advanced ATP testing devices contain a natural enzyme found in fireflies. This enzyme then activates a simple bioluminescent reaction when it encounters ATP retention. Hygiena's SystemSURE Plus and EnSURE Touch ATP Luminometers use bioluminescent technology to detect and measure extremely low ATP levels collected by testing devices. An effective way to gauge how clean a surface is is by counting the quantity of bioluminescence that results from an ATP reaction. This is due to the fact that the reaction's ability to produce light is directly correlated with the amount of ATP in the sample. The bioluminescence response is instantaneous, so results can be processed at the test site in seconds. The results are expressed as a numerical value on the luminometer display in relative illuminance units (RLU).

Why do I need a Luminometer in my Business?

ATP testing is used in a variety of industries, including food and beverage, food service, healthcare, hospitality, water quality, pet and veterinary care, personal care and cosmetics, industrial, and the environment. No matter what industry you're in, monitoring your ATP levels is an integral part of the cleaning process. EnSURE Touch and SystemSURE Plus are ATP hygiene monitoring devices equipped with a luminometer. It is critical for companies to have the right devices to measure ATP on their surfaces so that companies can measure and prevent cross-contamination.

Luminometer (when working with ATP test buffers)

Hygiena luminometers (in combination with ATP buffers) use bioluminescence to detect residual ATP as an indicator of surface cleanliness. Without a luminometer, it would be impossible to measure the ATP level on a surface and thus impossible to verify how it is being cleaned. Without proper hygiene control, this can lead to cross-contamination and thus a possible infection for anyone who comes into contact with it. By performing ATP tests, companies ensure the correct cleaning methods and the safety of staff, customers, and (depending on the sector of use) patients. Hygiena's EnSURE Touch has many advantages that make it suitable for use in facilities that want to perform ATP testing.

ATP tester/Luminometer:

Regardless of the sphere of life, control over the state of hygiene is inevitable. However, in some areas, it plays a particularly important role. In the food industry and food production facilities, you can expect most inspections from supervisory authorities. For the end consumer, it is not only important to obtain a clean product, safe for health, free from contamination or risk of infection by unwanted bacteria or diseases. It is also absolutely devastating for food companies to constantly receive complaints from customers about product quality. This damages the company's reputation in the long run and leads to large losses.

In addition to the usual visual inspection (which is neither sufficient nor reliable) or microbiological tests (which are time-consuming), there is a new method for the fast and efficient determination of ATP (adenosine triphosphate). With this method, you can quickly find out how dirty the surface is, assess the risks and solve the existing problem. This method reveals something that even the most observant and observant eye misses: invisible bacteria that can have dire consequences once they grow and spread.

Uses:

• Luminometers have a wide variety of applications in various fields of science. Here are some common uses:
• Enzyme Testing: They are often used to measure the activity of enzymes based on the detection of luminescent signals. For example, luciferase assays, in which luciferase enzyme activity is quantified by measuring the light emitted by the reaction, are performed on a large scale using luminometers. These tests are used in gene expression research, drug development, and other areas of research.
• Immunoassays: These are used in immunoassays based on the detection of luminescent signals to quantify analytes. For example, chemiluminescent or bioluminescent immunoassays are performed to measure the concentration of specific proteins, hormones, antibodies, or antigens. Luminometers provide sensitive and accurate measurements in these tests, allowing researchers to determine analyte concentrations.
• Reporter Gene Testing: Reporter gene testing is used to study gene expression and regulation. They are used to detect luminescent signals produced by reporter genes such as firefly luciferase or green fluorescent protein (GFP). By quantifying the light emitted, researchers can evaluate the activity of specific promoters, study transcriptional regulation, or evaluate the effect of drugs or genetic modifications on gene expression.
• Cellular Assays: Cellular Assays are widely used in cell assays to evaluate various cellular processes and signaling pathways. For example, intracellular calcium flux analyses can be performed using a calcium-sensitive luminescent dye, and the luminescent signal is measured using a luminometer. Other cellular assays, such as cell viability assays or apoptosis assays, may also use luminescent measurements.
• Environmental Monitoring: They are used in environmental monitoring to detect and quantify contaminants or contaminants. Luminous microbial biosensors can be used to assess water quality by measuring the luminous response of specific bacteria to pollutants. In addition, bioluminescence analysis can be performed to determine the presence of specific contaminants in environmental samples.
• Pharmaceutical Research: They play a critical role in drug discovery and development. They are used to evaluate the potency and potency of drug candidates in various tests, such as kinase tests or G protein-coupled receptor (GPCR) tests. Luminometers allow researchers to measure luminescent signals generated by biochemical or cellular reactions caused by drug-target interactions.