Thin film microfluidic pouches offer an innovative solution for reducing cross-contamination in chemiluminescence immunoassays through their unique structural design and fluid control technology. Their core advantage lies in combining the precise manipulation capabilities of microfluidic chips with the isolating properties of thin film materials, constructing a multi-layered anti-contamination system from multiple levels, including physical isolation, fluid control, reagent encapsulation, cleaning optimization, material selection, system integration, and operational specifications.
Physical isolation is fundamental to the reduced cross-contamination of thin film microfluidic pouches. They typically employ a multi-layered structural design, with different reagents or samples independently encapsulated in their respective microchannels or reaction chambers. The physical barrier effect of the film prevents direct contact between samples and reagents at the source. For example, in multi-item co-detection, each detection item corresponds to an independent thin film microfluidic unit. Waste or unbound markers generated during the reaction are confined to their respective areas, preventing diffusion to other channels and effectively reducing the risk of cross-contamination.
Fluid control technology further enhances the anti-contamination capability. Thin-film microfluidic pouches achieve precise control over fluid flow by meticulously manipulating the size, shape, and surface properties of microchannels. In chemiluminescence immunoassay, sample and reagent mixing, reaction, and cleaning processes are all automated via a microfluidic system according to a pre-programmed sequence, avoiding contamination that may be introduced by manual operation. For example, by designing specific flow channel structures, samples and reagents can be kept separate before mixing, achieving efficient reactions only in the reaction zone through diffusion or active mixing. After the reaction, unbound substances are immediately removed through independent cleaning channels, ensuring the independence of each step.
Pre-encapsulation and on-demand release mechanisms for reagents are another key feature of thin-film microfluidic pouches. Reagents are pre-encapsulated in specific chambers within the thin-film microfluidic pouch and released on demand via a destructible membrane or valve structure. This design not only reduces the chance of reagent exposure to the environment but also avoids contamination that may result from multiple sample additions. For example, during detection, laser or mechanical force can precisely burn through the membrane, releasing a quantitative amount of reagent into the reaction zone, ensuring accurate reagent dosage and no residue in each reaction, thereby reducing the possibility of cross-contamination.
Optimizing the cleaning process is equally important. The thin film microfluidic pouch, with its independent cleaning channels and efficient cleaning solution delivery system, ensures thorough cleaning of the reaction chamber after each reaction. Driven by a microfluidic system, the cleaning solution rinses the reaction area at a stable flow rate, effectively removing unbound markers, residual reagents, and byproducts. Furthermore, some designs incorporate reverse rinsing or pulsed cleaning techniques to further enhance cleaning effectiveness and reduce contaminant residue.
The choice of materials also significantly impacts anti-contamination performance. Thin film microfluidic pouches are typically made from biocompatible and chemically stable materials, such as polydimethylsiloxane (PDMS) and polyethylene terephthalate (PET). These materials not only do not adsorb samples and reagents but also withstand the strong acids, strong bases, or organic solvents that may be involved in chemiluminescence reactions, thus avoiding interference or contamination of the reaction by the materials themselves.
System integration and automated operation further enhance the anti-contamination capabilities of the thin film microfluidic pouch in chemiluminescence immunoassay. By integrating sample loading, reagent release, reaction control, signal detection, and data processing into a closed system, the thin film microfluidic pouch achieves fully automated operation, reducing contamination that may be introduced by human intervention. Simultaneously, the system's built-in calibration and quality control modules monitor the reaction status in real time, ensuring the accuracy and reliability of each test.
The establishment and adherence to operating procedures is the final line of defense for ensuring the thin film microfluidic pouch's anti-contamination performance. Rigorous training of operators ensures familiarity with the equipment's operating procedures and precautions, preventing contamination caused by improper operation. For example, it is stipulated that the equipment must be pre-rinsed before each test, and the microfluidic chip and thin film microfluidic pouch must be thoroughly cleaned after each test. Consumables are also replaced regularly, thereby maintaining the system's long-term stability and anti-contamination capabilities.
