Explanation of the types of sterilization indicator ink
Date: Mar 04 2025 From: Star Color
In the medical, pharmaceutical, laboratory, and food industries, sterilization is a crucial aspect of ensuring product quality. Different sterilization methods have their own characteristics, and sterilization indicator inks, as a key material that can visually verify the effectiveness of the sterilization process, are constantly being improved with the development of sterilization technology. There are different
sterilization indicator inks corresponding to various sterilization methods, and we will introduce them one by one below.
I. Steam Sterilization Indicator Ink
Steam sterilization uses high-temperature and high-pressure steam (121°C for 15 minutes or 134°C for 5 minutes) to denature and inactivate microbial proteins in a humid heat environment, which is a common sterilization method. The corresponding steam sterilization indicator ink changes color through the irreversible reaction of chemical substances in the ink, such as cobalt salts and pH-sensitive dyes, triggered by the high temperature of the steam. Common color changes are from blue to gray, and from green to colorless.
In practical applications, steam sterilization indicator ink is widely used in the medical device field, such as surgical instrument packs and dressing sterilization bags, and is also commonly used for the sterilization verification of laboratory glassware and culture media. For example, the chemical indicator tape, when pasted on the outside of the instrument pack, indicates that the instrument pack has completed the sterilization operation in the steam environment when the blue color turns gray.
II. Ethylene Oxide (EO) Sterilization Indicator Ink
The conditions for ethylene oxide sterilization are EO gas (concentration 450-1200mg/L), temperature (30-60°C), and humidity (40-80%). It works by alkylating microbial DNA/RNA with EO to block their metabolism. The color change principle of ethylene oxide sterilization indicator ink is that the dye in the ink undergoes an addition reaction with EO, changing its structure, resulting in color changes such as from orange to yellow and from purple to white. And it needs to match specific sterilization parameters, such as an EO concentration of 600mg/L, a temperature of 55°C, and a duration of 4 hours.
This type of ink is suitable for medical consumables, such as catheters, respiratory masks, and electronic device packaging, as well as for sterile vial labels in the pharmaceutical field, such as vials for vaccines. Relevant standards include ISO 11140-1 Type 4 (Multi-parameter Indicator).
III. Hydrogen Peroxide Plasma Sterilization Indicator Ink: Safeguarding Precision Instruments
Hydrogen peroxide plasma sterilization relies on hydrogen peroxide gas (concentration 58-60%), a plasma field, and a temperature of 50-60°C. It uses free radical oxidation to destroy the cellular structure of microorganisms. The hydrogen peroxide plasma sterilization indicator ink changes color through the oxidation of reducing dyes in the ink, such as indigo, by hydrogen peroxide. The color changes are from red to colorless and from blue to white. Due to the strong oxidizing environment of sterilization, this ink needs to have good corrosion resistance to avoid its own degradation.
It is mainly applied to precision instruments, such as endoscopes and minimally invasive surgical tools, as well as to the sterilization of equipment in laboratories dealing with highly pathogenic microorganisms in the field of biosafety. Relevant standards include AAMI TIR16, EN ISO 14937, etc.
IV. Formalin Sterilization Indicator Ink: An Important Aid in the Field of Biosafety
The conditions for formalin sterilization are formaldehyde gas (formalin) at a temperature of 60-80°C. It achieves sterilization by cross-linking microbial proteins and nucleic acids with formaldehyde. The color change principle of formalin sterilization indicator ink is that formaldehyde reacts with amine compounds in the ink to form Schiff bases. Common color changes are from yellow to brown and from pink to colorless.
In terms of application, it is mainly used for the sterilization indication of equipment in biosafety laboratories, such as animal house instruments and equipment contaminated by pathogens, as well as for the sterilization verification of clean areas in the pharmaceutical industry.
V. Radiation Sterilization Indicator Ink: Suitable for the Sterilization Verification of Specific Products
Radiation sterilization uses γ-rays or electron beams (dose 15-50kGy) to destroy microbial DNA through ionizing radiation. The color change principle of radiation sterilization indicator ink is that radiation causes the breaking of dye molecular chains or structural rearrangement, resulting in color changes such as from purple to pink and from green to yellow. And the depth of color change is positively correlated with the radiation dose.
This ink is suitable for disposable medical supplies, such as syringes and infusion sets, as well as for irradiation preservation food labels in the food packaging field. It complies with standards such as ISO 11137 and ASTM E2304.
VI. Emerging Sterilization Methods and Ink Innovations: Exploring Future Possibilities
With the continuous development of technology, emerging sterilization methods such as ozone sterilization and low-temperature plasma sterilization are gradually emerging, and the corresponding sterilization indicator inks are also constantly being innovated. The principle of ozone sterilization indicator ink is that ozone oxidizes the double bond structure in the dye, and it can be applied to the sterilization verification of water treatment equipment and food processing lines. The characteristic of low-temperature plasma sterilization indicator ink is that it can respond to low-temperature plasma, such as nitrogen plasma, and the color change is reversible. It is suitable for the sterilization indication of medical textiles and flexible electronic devices.
Zhongzhixing sterilization indicator ink comprehensively covers a variety of sterilization methods. Whether it is steam sterilization, ethylene oxide sterilization, or hydrogen peroxide plasma sterilization, etc., it can be accurately adapted.
In terms of performance, Zhongzhixing sterilization indicator ink has extremely high sensitivity and stability. It can quickly and accurately respond to various parameter changes during the sterilization process, with distinct color changes and high contrast, allowing operators to clearly determine the sterilization effect at a glance.
Zhongzhixing sterilization indicator ink has good printing adaptability and can be applied to various common packaging materials. The printing effect is clear and durable, ensuring stable performance in different application scenarios. Whether in the fields of medical devices, pharmaceutical packaging, or food packaging, Zhongzhixing sterilization indicator ink can provide strong support for sterilization work and is an ideal choice for ensuring product quality and safety.
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