Lateral flow assay manufacturing looks simple from the outside, but consistent performance depends on many tightly controlled process parameters. For POCT test strips, small changes in membrane lots, conjugate drying, dispensing volume, cutting width, humidity, and assembly pressure can affect sensitivity, background, flow time, and reproducibility. A stable manufacturing process is therefore essential for both regulatory compliance and commercial success.
Material selection and incoming inspection
The main components of a lateral flow strip include sample pad, conjugate pad, nitrocellulose membrane, absorbent pad, backing card, antibodies or antigens, labels, buffers, desiccants, pouch materials, and cassette components. Each material should be evaluated and controlled according to its impact on final product performance.
Critical raw materials such as nitrocellulose membranes, antibodies, recombinant antigens, colloidal gold, fluorescent labels, and treated pads should have defined acceptance criteria. Incoming inspection may include appearance, dimensions, flow rate, protein binding performance, moisture content, and functional testing with reference samples.
Dispensing, drying, and lamination controls
Dispensing accuracy directly influences test line intensity and control line reliability. Manufacturers should control line position, dispensing volume, line width, nozzle condition, and environmental conditions during dispensing. Drying temperature and time should be validated to preserve reagent activity while achieving adequate stability.
Lamination must ensure correct overlap between pads and membrane. Insufficient overlap can cause flow interruption, while excessive pressure may alter flow characteristics. Cutting width and blade condition should be monitored because uneven strips can create inconsistent migration and signal distribution.
Environmental control and contamination prevention
Humidity is one of the most important variables in lateral flow manufacturing. High humidity can affect conjugate release, membrane flow, and long-term stability. Temperature, dust, biological contamination, and operator handling should also be controlled. Clean production areas, appropriate gowning, regular cleaning, and line clearance procedures reduce the risk of mix-up and contamination.
Quality control strategy
A robust quality control strategy includes in-process inspection and finished product release testing. In-process controls may cover membrane dispensing, drying records, strip dimensions, assembly checks, pouch sealing, and desiccant presence. Finished product testing should include negative, weak positive, positive, and sometimes interference or matrix samples depending on product requirements.
DueBio provides POCT test strip development and manufacturing support for partners seeking consistent lateral flow assay products for global markets.