Personalised sensors for medical tests
Paper-based sensor could test for multiple conditions without the need to visit the doctor.
Sensors play a vital role in monitoring the integrity of large structures such as buildings, transport and utilities infrastructure, as well as safeguarding our wellbeing at home via detection of smoke and dangerous gases, such as carbon monoxide. Of equal importance, however, is the use of sensors for routine diagnosis of a range of diseases and conditions so that patients can manage their personal healthcare at home as well as at the doctor’s surgery.
Researchers at Southampton are developing cheap paper-based sensors that will be used to test for multiple medical conditions as well as a single condition with different levels of quantification on a single test strip.
Professor Rob Eason, Associate Dean for Research in Physical Sciences and Engineering at the University, and his team use lasers to pattern multiple flow channels into paper sensors, which could diagnose a range of different conditions such as tuberculosis (TB), diabetes, high cholesterol or other tests that could be specified on a patient-by-patient basis. Rob and his team are part of Sensors@Southampton, a network of research teams across the University, which shares ideas and expertise in order to advance the science of sensors.
Global sensor market
Working with colleagues in Medicine, the Institute for Life Sciences and Health Sciences, Rob and his team – Dr Collin Sones, Dr Ioannis Katis and Peijun He – focus on developing paper sensors that should cost a few pence to produce and could be used across the world, particularly in remote settings where it is difficult to get to a doctor.
“With over seven billion people in the world, medical sensors are a global market,” says Rob. “Take the familiar pregnancy test for example – hundreds of millions are sold around the world every year and provide the user with a rapid yes or no answer to a very important question. But what if we could make a more versatile test that could detect a range of life-threatening diseases such as TB, malaria, hepatitis or other more recent problems at the same time, on just one single test strip. This would really help both in the developed and developing world.”
The paper sensors developed by the team should be printable in a matter of seconds. After soaking the paper in a monomer, a laser is used to convert sections of the monomer into a stable polymer forming channels that can be as small as 100 microns wide – the diameter of a human hair. Rob explains that a single paper sensor could have tens of separate flow channels on it, each one testing for a different condition using the familiar colorimetric indicator mechanism as in a pregnancy test.
Not only could you test for multiple conditions with one human sample such as urine or blood plasma, but you could also test for the severity of a condition.
“Not only could you test for multiple conditions with one human sample such as urine or blood plasma, but you could also test for the severity of a condition,” says Rob. “For example in a multiple test strip the colour change observed can indicate whether the disease or condition is present in a mild, moderate, severe or critical level and hence what your next actions need to be,” he adds.
Working with Dr Paul Elkington, Associate Professor in Respiratory Medicine, Rob and the team are developing a paper-based test for TB. “TB is traditionally thought to be a disease that was prevalent only in the past, but in certain countries such as India it is responsible for more than two million deaths per year, and in the UK it is making a comeback with parts of London having higher rates than countries such as Rwanda or Iraq. In addition to the active form of TB there is also a latent form where you have the disease, but no symptoms, but this can develop into active TB at a later date. We are looking at creating a sensor that can detect this severity,” says Rob.
He explains that the team’s sensor technology could be used to test for other diseases such as MRSA and clostridium difficile in hospitals, infectious diseases at home to minimise the spread of infection, or even HIV. “Detecting diseases such as HIV at home does raise important issues around a person’s reaction to a positive result. However, our paper test could be made in such a way that the result is encoded. The user would then scan the result using a smartphone, send it to their health centre where the diagnosis could be made, and the user would then receive the support needed to deal with the outcome,” says Rob.
The versatile technology could also be used in other industries such as in veterinary science. In the UK, diseases such as foot and mouth periodically arise and threaten the entire cattle population. A paper sensor could be used immediately by the farmer, the results sent by smart phone to the authorities, and the infection isolated before it had a chance to spread more widely. “The use of smart phones coupled with our test would be vital in this case as it would allow the government to know where the outbreak was, and provide information on whether the disease was spreading and how to best contain it,” says Rob.
Medical tests for all
The researchers are in the process of creating a spin-out company to manufacture the paper sensors and have also had discussions with 80 companies to establish the optimum route to commercialise a whole host of medical sensors. “Several large global diagnostic companies have expressed a keen interest in our technology and are keen to work with us on developing a range of sensors. Our paper-based platform combined with their biochemical expertise and regulatory approval could open up the possibility of rapid, cost-effective and mass-distributable medical tests available for all,” says Rob.
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