Scientists turn sanitary pad into life-saving disease detector

By Sola Ogundipe

Scientists have turned what is generally regarded as a monthly inconvenience into a medical marvel and unlocked a new frontier in disease detection—one that’s discreet, fast, and astonishingly powerful.

In a quiet lab nestled within ETH Zurich, Switzerland’s premier science and technology university, researchers have transformed the humble sanitary pad into a potential lifesaver. Their innovation is a paper-thin sensor embedded in the pad that can detect early signs of serious diseases long before a single symptom appears.

For centuries, menstrual blood has been dismissed as waste; however, this new technology is changing that narrative, using it as a rich source of biological data. The sanitary pad, indistinguishable from any off-the-shelf product, hides a diagnostic strip just beneath its surface. It is incredibly easy to use; the wearer simply snaps a photo of the strip and uploads it to a smartphone app. Within minutes, artificial intelligence analyses the image, comparing it against a vast database to flag potential health concerns.

The sensor, called MenstruAI, costs around £1 (N2,000) to manufacture and contains gold nanoparticles which react when a protein is detected.

The test easily detects C-reactive protein (CRP) – a marker for inflammation and infections like colds and flu. It also detected carcinoembryonic antigen (CEA), often elevated in the presence of tumours, and also CA125 – a protein linked to ovarian cancer and notoriously difficult to detect early.

The sensor works much like a COVID-19 test strip, with lines or dots appearing depending on the biomarkers present, with darker colours indicating higher concentrations. The entire process—from pad to prognosis—takes less than 10 minutes.

This breakthrough could revolutionise the monitoring of health conditions, especially those that often go undetected until they become serious. Among these are urinary tract infections (UTIs), type 2 diabetes, and ovarian cancer, which are just the beginning. The implications for global health—especially in regions with limited access to diagnostic labs—are profound.

Dr Ana Ferreira, one of the lead researchers, says the goal is to make health monitoring “as routine and effortless as brushing your teeth.” And with this pad, that future may be closer than we think.

“At the moment, we have a proof-of-concept with three biomarkers relevant for infection, gynaecological disorders and tumour development. The sensor is embedded into a soft silicone casing that protects it. It’s designed so that we can control the volume of blood that comes into contact with the paper strip,” said Lucas Dosnon, a nanotechnology researcher at ETH Zurich and lead author of the study, recently published in Advanced Science News.

The team plans to include many more protein-based markers which will be able to point to a variety of other diseases or give general health insights. Gold nanoparticles are already used in a range of diagnostic applications because of their unique optical properties, including their ability to scatter light – which means they generate visible colour changes that can be seen with the naked eye.

Women lose roughly 30 to 50 ml of blood during their monthly period, and menstrual blood sensors have been in development for the past 10 years at least. The big attraction is that samples don’t need to be collected by needle and are readily available every month.

In 2019, a team at Stanford University in California compared samples of menstrual blood with blood that circulates through the body from 20 women over two months. Results in the journal Clinical and Laboratory Medicine showed menstrual blood could reliably estimate levels of several biomarkers – including for diabetes and inflammation – as well as reproductive hormones, and so could be an alternative source for diagnosis and health monitoring.

In 2022, Paul Blumenthal, a professor emeritus of obstetrics and gynaecology at the Stanford School of Medicine, and Dr Sara Naseri, a former Stanford Medicine visiting scholar, developed a smart menstrual pad that could detect human papillomavirus, or HPV, which is linked to cervical cancer.

Naseri went on to co-found a company called Qvin and develop the first FDA-approved diagnostic menstrual pad, known as the Q-Pad. Women wear the pad as normal, then a blood collection strip is sent to a laboratory to be analysed.

Results are returned within five days and, as well as HPV, can identify biomarkers for pre-diabetes, anaemia, perimenopause, endometriosis and thyroid health.

The latest test is not designed to replace laboratory tests but to give early indications of potential problems that may require more detailed investigations. It could be used for early screening of the general female population who want to have a better overview of their health, or it could help monitor disease progression in people who have already been diagnosed.

One example might be the inflammatory bowel condition Crohn’s disease, where some patients need to do a monthly blood test to monitor their inflammation status. The next step is to test it in a larger group of participants (the field study was a small group of volunteers). Once it has approval, it could be sold over the counter.

Gold is costly, but expenses are reduced when manufacturing is scaled up and very little is needed. Gold nanoparticles are easy to use and very versatile; hopefully this project can help to break counterproductive taboos.

Dr Karen Morton, a consultant gynaecologist based in Guildford, noted, “This technology is interesting, but there is a lot more to understand about how it may be used to really help improve women’s health, if at all. The concern is that this may just encourage the worried well to spend more of their money.”

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