The Critical Role of Vacuum Technology in Nucleic Acid Testing

As a key measure for pandemic prevention and control, nucleic acid testing has gradually become routine. But after undergoing so many tests, do you know how the process works? How does it detect the COVID-19 virus? What role does vacuum technology play in the nucleic acid testing process? Let’s explore these questions today.

Nucleic acid testing involves five steps: sampling, sample retention, storage, nucleic acid extraction, and machine testing.

1. 1.

   Collecting human secretions: Nasal or throat swabs are used to collect samples from the nasal cavity, the back of the throat, or both sides of the tonsils.

2. 2.

   Sample retention by medical staff: The swab head is immersed in a cell preservation solution, the handle is broken off, and the tube cap is immediately tightened.

3. 3.

   Storing and transporting samples: The sample is placed in a sealed bag, stored properly, and promptly sent for testing.

4. 4.

   Nucleic acid extraction: The sample is sent to a laboratory for nucleic acid extraction.

5. 5.

   Fluorescent PCR amplification: The extracted material undergoes fluorescent PCR amplification.

The first three steps are familiar to most people, while the last two are not directly observed by the public. The fluorescent PCR amplification step, in particular, may seem highly technical. Most COVID-19 nucleic acid testing kits currently use the fluorescent quantitative PCR detection method. This method is the core technology enabling rapid and accurate nucleic acid testing.

The Critical Role of Vacuum Technology in Nucleic Acid Testing

So, what is the fluorescent quantitative PCR detection method? First, it’s important to understand what PCR is. PCR (Polymerase Chain Reaction) is a molecular biology technique used to amplify specific DNA segments. It can be thought of as a special form of DNA replication outside a living organism. The most significant feature of PCR is its ability to greatly amplify tiny amounts of DNA, making it possible to detect even minimal traces of the COVID-19 virus in a sample.

Conventional PCR detection relies on repeated temperature changes to achieve DNA amplification. However, this technique is complex and unable to provide precise quantification, making it unsuitable for pandemic monitoring. The fluorescent quantitative PCR method, on the other hand, detects unique viral gene sequences. Through PCR amplification, the target DNA sequences are exponentially increased. Each amplified DNA sequence binds to a pre-added fluorescently labeled probe, producing a fluorescent signal. The accumulated fluorescent signal is then measured to determine whether viral nucleic acids are present in the sample. This is currently the most widely used method for confirming positive cases.

The Relationship Between Fluorescent Quantitative PCR and Vacuum Technology

Now that we have a general understanding of the nucleic acid testing process, how is fluorescent quantitative PCR detection related to vacuum technology?

In the final machine testing step, medical staff need to observe whether fluorescent signals are produced by COVID-19 DNA sequences in the sample. How is this observed? Through a key component of fluorescent PCR nucleic acid testing equipment: the fluorescent filter.

Fluorescent filters are critical components used in biomedical and life science instruments. Their main function is to separate and select specific spectral bands of excitation light and emitted fluorescence in biomedical fluorescence analysis systems. Molecules absorb excitation light at specific absorption bands and then emit longer-wavelength radiation spectra, forming fluorescence spectra. This is the working principle of fluorescent filters. Fluorescent filters include excitation filters, emission filters, and dichroic mirrors. High-performance fluorescent filters significantly improve the accuracy and reliability of viral quantitative detection.

Since the new round of COVID-19 outbreaks in 2022, optical instrument manufacturers across China have continued to ensure the production and supply of fluorescent filter components. For example, Shenyang Instrumentation Research Institute Optical Company, a leading enterprise in PCR filter components for nucleic acid testing, activated a Level 3 emergency response plan at the end of March. They implemented closed-loop management and maintained 24/7 production to ensure the normal operation of nucleic acid testing nationwide.

The Production of Fluorescent Filters and Vacuum Technology

Fluorescent filters are an application of optical filters in the medical field. The production of optical filters is a complex engineering process involving multiple specialized technologies, including vacuum acquisition technology, vacuum measurement technology, computer-aided design technology, optical characteristic detection technology, electronic circuit technology, and material characteristic detection and preparation technology.

High-quality fluorescent filters use a single piece of colorless transparent glass as a substrate, with coatings applied on both surfaces of the glass. In the vacuum chamber of a vacuum coating machine, dielectric coating materials are evaporated through heating or electron beam bombardment, and the vapor deposits onto optical surfaces. During evaporation, parameters such as heating, vacuum level, substrate positioning, and rotation are controlled to produce optical coatings with specific thicknesses and uniformity.

If the vacuum level in the coating machine does not meet requirements, the probability of collisions between vaporized molecules and residual gas molecules increases. This significantly reduces the kinetic energy of the vaporized molecules, preventing them from reaching the substrate or overcoming the adsorbed gas layer on the substrate. Even if they勉强 break through, their adhesion to the substrate is weak. This results in loose, low-density coatings with poor mechanical strength, reducing the refractive index and hardness of the filter layers. Thus, without vacuum coating technology, fluorescent filters cannot be produced, and nucleic acid testing cannot be performed quickly and accurately.

Applications of Filter Technology

In the production of optical instruments, filter preparation processes mainly include evaporation deposition, ion beam sputtering (IBS), plasma sputtering, atomic layer deposition (ALD), and CAD downloads. All of these processes operate under vacuum conditions.

Filters are widely used in production and daily life. For example, anti-reflective filters are used in corrective lenses for vision, high-reflection filters are applied in car mirrors, and various filters are integrated into the core components of projectors widely used in business settings. Monochromators, a key component of biochemical analyzers used in medical examinations, often employ narrow-band filters. Digital cameras use long-pass and short-pass filters. Various optical instruments, liquid crystal displays, anti-counterfeiting technologies, optical communication, and laser technology are all closely related to advancements in filter technology.

It can be said that without the development of filter technology, many modern emerging technologies would not have achieved their current success. Though small in size, filters are widely used in national economy and defense construction and are increasingly valued by scientists and technicians.