Description

The BFNC series backed nitrocellulose (NC) membranes are purpose-engineered for lateral flow immunochromatographic assays (LFIA), including rapid test strips, POCT diagnostics, and colloidal gold (GICA) assays. Each membrane is laminated onto a clear polyester backing, providing excellent mechanical strength, uniform thickness, and consistent performance across production batches, making them ideal for automated or manual test strip manufacturing.

With a range of pore sizes (8–12 μm) and capillary flow speeds, BFNC membranes allow developers to optimize assay sensitivity, flow rate, and detection time. These membranes are widely used in COVID-19 rapid test strips, pregnancy tests, drug detection strips, and other gold-labeled lateral flow assays, delivering stable fluid flow, high protein/antibody binding capacity, and sharp, reproducible test line formation for reliable diagnostic results.

Specifications

Parameters	BFNC095B	BFNC140B
Membrane Material	Nitrocellulose	Nitrocellulose
Appearance	White,Flat, No Defects and Matters, 100% Backlit Inspection	White,Flat, No Defects and Matters, 100% Backlit Inspection
Capillary Speed CFT(s/40mm)	95±25	125±30
Pore Size	12 μm	8 μm
Thickness (incl. backing)	255±15 μm	240±15 μm
Backing Material	Polyester	Polyester
Inner Dia. of ReelCore	76.2 mm	76.2 mm
Reel Core Material	Polyethylene	Polyethylene
Width	20mm / 25mm	20mm / 25mm
Length	100 m	100 m

Notes: Capillary speed, backing thickness, width, and length can be customized according to your assay requirements.

Features

Backed NC membrane: Laminated onto clear polyester backing for enhanced mechanical strength, stability, and ease of handling during automated or manual strip production.
High inter- and intra-lot consistency: Strict quality control ensures uniform thickness, smooth surface, and consistent performance between batches.
Controlled pore structure & capillary flow: Pore sizes (5–12 μm) and corresponding capillary speeds allow precise tuning of fluid migration for optimal assay sensitivity and reaction time.
Strong protein/antibody binding: Nitrocellulose ensures reliable immobilization of capture reagents for sharp and reproducible test and control lines.
Rapid and uniform wetting: Hydrophilic membrane promotes even sample absorption and consistent lateral flow.
Flexible grade selection: Smaller pores/slower flow rates enhance sensitivity; larger pores/faster flow rates enable rapid assays or accommodate viscous samples.
Smooth, defect-free surface: Produces clear, easy-to-read test lines with minimal background signal.

Applications

Diagnostic Applications

IVD & POCT rapid test manufacturers
Environmental & food safety rapid testing
Veterinary diagnostic kit developers

Research Applications

Academic and industrial protein analysis labs
Molecular biology research groups

Training & Demonstration

Teaching labs and training centers

FAQ

Q1. How do I choose the right membrane grade (pore size / capillary speed) for my lateral flow assay?
- Smaller pore size / slower capillary-flow membranes (e.g. 8 µm) provide slower fluid migration, giving more time for antibody/antigen binding — ideal for high-sensitivity assays or low-concentration analytes.
- Larger pore size / faster flow membranes (e.g. 12 µm) enable faster result times, suitable for rapid-response tests, viscous samples, or assays where speed is more important than maximum sensitivity.
- For new assays, a middle-range grade often balances flow rate and sensitivity; users can optimize from there.
Q2. Why choose backed NC membranes over unbacked membranes?

Backed NC membranes (with polyester support) offer improved mechanical strength and handling robustness, facilitating strip manufacturing, assembly, and stability — especially important in automated or high-throughput production lines. The backing also ensures a uniform, usable surface with reliable binding capacity, reducing variability compared to unbacked membranes.
Q3. What other factors beyond membrane choice affect lateral flow assay performance?
- Sample viscosity or sample type — e.g. whole blood, serum or urine — affects flow through the membrane; membrane grade and flow rate should be matched to sample characteristics.
- Compatibility of reagents, surfactants or wetting agents — membrane hydrophilicity and reagents can influence binding kinetics and flow behavior. It is recommended to test antibody/antigen with the chosen membrane under intended conditions before mass production.
- Striping/coating conditions and drying/curing process — after applying capture reagents, proper drying under controlled humidity and temperature is critical to fix reagents stably. Improper drying or storage may lead to variability or weak signal.
Q4. My assay shows weak signal or low sensitivity — what might cause this and how to troubleshoot?

Possible causes: membrane pore size too large (leading to flow too fast, insufficient binding time); insufficient antibody/antigen coating density; improper striping or drying; poor compatibility between reagents and membrane surface or wetting agents.

Recommended actions: switch to a slower-flow (smaller-pore) membrane to increase analyte–antibody interaction time; verify and adjust coating concentrations; ensure proper drying/curing after striping; optimize buffer conditions or blocking strategies to reduce non-specific binding and improve binding efficiency.
Q5. My assay is too slow — results take too long. What can I do?

If the assay run time is too long, consider using a higher flow-rate (larger pore size) membrane. That will shorten capillary flow time and speed up sample/conjugate migration, resulting in faster readout. Be aware that increasing flow rate may compromise sensitivity, so balance based on detection requirements.
Q6. How should I store and handle NC membranes to maintain performance and consistency?
- Store membranes in a low-humidity environment (preferably < ~40% RH) and avoid moisture exposure, which may degrade binding properties or cause variability.
- Keep membranes flat; avoid bending or creasing — especially backed membranes — to prevent defects that could affect flow or striping uniformity.
- After striping (application of capture antibodies or reagents), ensure proper drying/curing (e.g. by controlled temperature/humidity) to fix reagents; improper drying or storage in humid conditions may lead to unstable binding or inconsistent results.
Q7. Can assay sensitivity be enhanced beyond standard NC membranes?

Yes — for applications requiring higher sensitivity or lower detection limits, modifying the membrane (e.g. via nanofiber coatings or specialized treatments) can help improve performance while maintaining flow characteristics. For very sensitive applications, consider using such enhanced membranes or optimizing the combination of membrane, reagents, and assay conditions.
Q8. For which types of tests / analytes is NC lateral flow membrane most suitable?

NC lateral flow membranes are widely used in point-of-care diagnostic tests based on immunochromatographic format — including infectious disease antigen/antibody detection, drug-of-abuse screening, pregnancy tests, animal disease diagnostics, food safety screening (e.g. contaminants or allergens), and other rapid immuno/colorimetric/fluorescent strip tests. Membrane grade (pore size, flow rate) should be selected based on target analyte concentration, sample matrix, and required assay speed vs sensitivity.

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