6 Ultra-Low Cost Diagnostics
With the ultimate goal of improving worldwide health, there has been a push in recent years to make diagnostics readily available throughout the globe, including in resource poor settings. While stability, size, and ease of use are important factors, the key to truly democratizing diagnostics is reducing the cost. Here we take a look at 6 promising ultra-low cost diagnostic technologies, which could help take the tools to where they are most needed.
1. The Paperfuge - A 20-cent, hand-powered blood centrifuge
Centrifuges can play a critical role in diagnosing a wide range of diseases, including malaria, a disease responsible for approximately 429,000 deaths in 20151. By spinning samples at high speeds, blood components and malaria parasites can be separated into distinct layers. However, traditional centrifuges can be bulky and expensive, and require a power source, making them unsuitable for many underserved regions.
Inspired by whirlygigs, a type of spinning toy, Stanford bioengineer Dr Manu Prakash developed the Paperfuge. Made out of a paper-disc and string, the device rotates up to speeds of 125,000 rpm, and can separate malaria parasites from red blood cells in 15 minutes.
2. The Foldscope – An origami-based paper microscope for less than a dollar
Another invention from Stanford Bioengineer Dr Manu Prakash, the foldscope is an optical microscope which can provide over 2,000x magnification with submicron resolution. It starts off as a flat sheet of paper (increasing ease of transportation) and takes under 10 minutes to construct, simply by a series of folding steps. Added to this, the device is small and lightweight, and well suited to use in underserved regions with no reliable power sources, where traditional microscopes are not appropriate.
One of the main aims of the foldscope was to bring hands-on-science to people around the world, helping to encourage interest in science and the world around them. However, its potential in the future of disease diagnosis was also realised, and it is hoped that Foldscopes can be adapted and trialled for this purpose.
3. A US $2 Portable Zika Test
Current antibody-based methods of detecting Zika virus are not specific enough to discriminate between Zika and other flaviviruses such as Dengue, while PCR-based methods are very costly, time consuming, and require large equipment and skilled operators. Since detection is needed in a wide range of environments, ranging from busy airports to remote communities, there is a need for a simple, portable and low-cost method to rapidly identify infected patients.
Scientists from Florida Atlantic University are developing a device the size of a tablet, which uses saliva samples to detect Zika virus in 15 minutes, made from paper- or plastic-based materials costing just US$2. A grant from the Florida Department of Health is currently being used to establish proof-of-principle, with hopes to eventually commercialize the test.
4. A paper-based biochip to detect whooping cough
Despite being a vaccine-preventable disease, there are an estimated 16 million pertussis cases worldwide2. Characterised by a hacking (whooping) cough, pertussis shares early symptoms with the common cold, but can become very serious, especially for the very young.
In efforts to reduce the cost and turnaround time of current detection methods, researchers from the University of Texas at El Paso have developed a paper-based 3D microfluidic point-of-care biochip, which uses samples from nasal swabs to detect the presence of the bacteria in under one hour. The chip, which costs only a few dollars, uses isothermal DNA amplification technology, and has shown high sensitivity and specificity, with results comparable to PCR.
5. A one cent multifunctional Lab-on-a-chip
With the goal of democratizing diagnostics, researchers from Stanford University School of Medicine developed a lab-on-a-chip that costs just 1 cent. Made from a combination of microfluidics, electronics, and inkjet printing technology, the device requires no clean room or trained personnel to create, and can separate cells based on their intrinsic electrical properties. The label-free process saves time and money, and improves the precision of analysis.
Some of the applications that the chip can be used for include isolating rare cells, counting cells, and capturing single cells. By bringing these functions to settings where current technologies such as flow cytometry are unaffordable or unsuitable, a range of diseases could be diagnosed more easily worldwide.
6. Cell-free, paper-based sensors for molecular diagnostics at US$0.10-US$1 per test
Led by researchers from the Wyss Institute for Biologically Inspired Engineering at Harvard University, and building on previous work with Ebola virus, a paper-based diagnostic system has been developed for strain-specific detection of Zika virus.
After RNA amplification, droplets are administered to paper discs, which change colour if Zika virus is present. If Zika is detected, a CRISPR-Cas9 based step can distinguish between Zika strains. In addition to a cost of between US$0.10-$1 per test, the system can be safely freeze-dried, and be rapidly tailored to detect other emerging diseases.
These examples are just a small glimpse into some of the many innovative technologies
being developed to improve access to diagnostic tests worldwide. The use of low cost
materials such as paper seems to be a key theme in helping to push down the costs of
these diagnostics, and further advances in what can be done with this versatile material
should see a continued increase in the range and ability of future tests.
1. http://www.who.int/features/factfiles/malaria/en/ (Accessed 09 May 2017)
2. https://www.cdc.gov/pertussis/countries/ (Accessed 09 May 2017)