Lateral flow tests have been in broad use for human applications since the 1980s, and have helped doctors, and eventually the public, to make preliminary detection of conditions ranging from pregnancy to flu to HIV and most recently COVID-19. Over the course of more than four decades, lateral flow technology has been repeatedly honed and improved upon, making it a reliable first detection tool in the diagnosis and treatment of many communicable and infectious diseases. Importantly, demand for lateral flow technology has grown well above and beyond its most recognized uses to include novel applications in veterinary sciences, microbiology, food science, and other areas.
A Brief History of Lateral Flow Technology
Lateral flow technology is relatively young, with a history spanning fewer than 50 years. Shortly after the conclusion of World War II, membrane filters were developed for increased efficiency and accuracy in water safety testing. The application of these membranes was later expanded to include testing for the sterility of other fluids, followed by microbiological applications. These early membrane filters served as the progenitors and inspiration for the lateral flow membranes that are in use today, but it would be several decades before they would appear on the market.
In the late 1980s, lateral flow assays became widely commercially available and were used by the public primarily for the measurement of hCG, to detect pregnancy. Since then, lateral flow tests have been developed for the detection of myriad conditions, including influenza A/B, malaria, human immunodeficiency virus (HIV), respiratory syncytial virus (RSV), and likely the most well-known today, SARS-CoV-2, or COVID-19.
Because lateral flow technology originated in private industry rather than academia, it rapidly became more sophisticated. In the 1990s, immunoassay developers knew that lateral flow tests could be used for a wide variety of human applications, as well as veterinary, food science, and other applications. But no membrane manufacturer was optimized material for this. That was due, in part, to the fact that existing membrane casting technology wasn’t specifically designed to manufacture lateral flow membranes. Early that decade, MilliporeSigma, the life science business of Merck KGaA, Darmstadt, Germany, was approached to develop and produce lateral flow membranes in large quantities. To do that, a machine specific for production of lateral flow membranes had to be developed and constructed first, and that was no easy task. The equipment required to produce lateral flow membranes was, and remains, highly technical in nature, requiring years to design, develop, build, and install. But this wasn’t just about new machinery; it marked a critical increase in capacity, which at the time was a major roadblock to growth in the market and expansion to new applications. Importantly, it also led to one of the hallmarks of the industry: membranes developed with a high level of consistency in both function and design so that they could be used across many applications with confidence and without modification.
How does lateral flow technology work?
Most simply, lateral flow technology relies on the combination of a nitrocellulose membrane, nanoparticles, and capture molecules— in the case of infectious diseases, antibodies— to analyze target molecules in a sample and then produce a visible result. The sample is put into the test through a sample collection window, and capillary force moves the sample liquid through a series of porous pads containing the reactive molecules that then move through the membrane to produce a negative or positive result. Truthfully, as simple as lateral flow tests are to use and interpret, they’re not simple to manufacture or to make work at accuracy levels required in the market.
That’s why MilliporeSigma and other manufacturers have reference materials to help users really understand basic information about lateral flow technology, membranes, and test development programs. MilliporeSigma also runs workshops for test developers to help them drill deeper into the specifics of test development and gain the skills and knowledge necessary to develop and distribute functional, accurate lateral flow tests. This has become more important over recent years.
Interestingly, the basic operation of lateral flow technology hasn’t changed much over time. The tests function today in a very similar fashion to the way they functioned in the 1990s. But there have been improvements in lateral flow technology over the past three decades. Perhaps the most obvious of these improvements is the increased consistency of the materials used in the manufacture of lateral flow tests. Not far behind is increased consistency of the reagents used in the test strips.
What’s Coming Next for Lateral Flow Technology?
Despite having gone through multiple reinventions to today’s level of precision, there’s still room for additional improvements and innovation. The market continues to evolve in the direction of quantitative capabilities, allowing these tests to become more versatile in their end use application. This shift will also require the development of new raw materials and testing methodologies that can provide accurate quantitative results. These new tests will do more than detect infectious diseases, but also cancer and even concussion biomarkers. We’re looking towards a future for lateral flow tests where a soccer mom can test her child at home after being headbutted during the game to find out if he has or is at risk for a concussion, all before ever heading to the emergency room. The market has been heading towards this level of granularity and specificity for some time, and that trend is being pursued aggressively. Along with new types of conditions and specificity, there’s a push towards automation. With automation, the hope is that all lateral flow devices will someday soon be able to report results directly to mobile phones and doctor’s offices. This will essentially tie lateral flow tests in with the processes we already use in our everyday lives. Lateral flow technology has already achieved precision, accuracy, and sensitivity to levels we couldn’t have imagined more than 40 years ago. Its reliability and cost-effectiveness will carry it into new applications for the next 40 years.
This article was contributed by ALFC 2024 sponsor MilliporeSigma. See below for additional bonus content from MilliporeSigma.
Which membrane do I choose?
Given the wide range of membrane characteristics, let MilliporeSigma’s technical experts help you find the optimal membrane for your assay specifications. The lateral flow assay guide provides information on the key aspects of immunochromatographic test strip design, the materials used, their integration with reagents, and manufacturing processes. Your choice of lateral flow membrane defines much of the performance characteristics of your assay. With such diverse choice in membranes available, it’s nice to know you can discuss your specific application specifications with the technical experts who actually make the membrane.
Request your copy of the Rapid Lateral Flow Test Guide or discuss your particular assay parameters an expert today.
