Revolutionary Sensor Detects Heavy Metals in Sweat: The Future of Toxicity Testing

Recently, researchers in Brazil developed a portable medical sensor that can identify and detect the presence of heavy metals, such as lead and cadmium, in human sweat. This new technology allows individuals to screen and diagnose themselves for exposure to potentially toxic substances, improving health outcomes. With its ability to accurately diagnose the presence of heavy metal poisoning, this new innovation is set to revolutionise how we monitor and maintain our health. What challenges do heavy metals present, what did the researchers develop, and how could self-testing systems help improve health?

What challenges do heavy metals present?

The development of new technologies has enabled mankind to survive in rapidly changing climates, fight off diseases, and even step foot on other worlds. But while all of these advances have undeniably helped humanity, they have also come with many challenges that continue to plague modern civilisation today. Capitalism combined with excess sees large amounts of non-recyclable waste, which risks polluting the environment for decades to come, the elimination of most diseases has encouraged the evolution of superbugs that are impossible to treat, and the development of agricultural industries has seen widespread destruction of habitats and loss of wildlife. 

Another one of these challenges is the prevalence of heavy metals (such as lead and cadmium) in our environment. While heavy metals exist in nature, they are often locked into the rock that remains inaccessible to life. The discovery of metalworking and mining has seen man search for precious stones deep in the earth’s crust, but the recovery of such valuable minerals has also introduced heavy metals into our environment. Large-scale industrial operations combined with poor practices have now seen heavy metal levels rise in the soil, sea, and air. 

When it comes to humans, heavy metals are problematic as they are readily absorbed by tissue, making it difficult to remove them once ingested. Once in the body, heavy metals can kill either by interfering with normal cell functions in the short term (i.e., heavy metal poisoning) or by encouraging cancer growth in the long term. While removing heavy metals in the bloodstream is possible, the symptoms from excessive levels of heavy metals can be difficult to spot at the early stages and irreversible once identified. 

For these reasons, numerous laws have been introduced worldwide to try and limit the number of heavy metals introduced into the environment. One example is the EU RoHS directive which specifically bans lead, cadmium, and other cacogenic materials from consumer electronic products. By eliminating these toxic compounds in electronics, users are not directly exposed to toxic compounds, and electronic devices that are eventually thrown into a landfill do not leach these compounds into the surrounding environment. However, heavy metals still persist in products, and their abundance in nature presents a daily risk to health.

Researchers develop portable heavy metal sensor

Recognising the challenges faced by heavy metals, researchers from the University of São Paulo (Brazil) developed a unique solution to detecting heavy metals in sweat utilising simple materials. Their sensor is manufactured by adhering a layer of copper tape over a layer of PET, creating a sensor pattern mask on top of the copper, and then exposing the copper layer to ferric chloride. Only exposed areas are etched away, leaving behind the copper sensor. Finally, the sensor is washed in distilled water to induce a degree of corrosion which help the sensor detect the presence of heavy metals when in contact with sweat.

When in contact with sweat, the presence of heavy metals results in a change in potentials across the electrodes, and this is detected by an external potentiostat. Not only can heavy metals be detected, but their concentrations can also be determined, allowing users to identify potential cases of excessive heavy metals. 

According to the researchers, the sensor developed is simple to manufacture and can be operated by untrained individuals, removing the need for professional staff and testing equipment. Thus, those in remote places or environments where medical access is unreliable can track their own health.

How could self-testing help improve health?

While doctors will be quick to warn against self-diagnosis and treatment, there is a lot of value in self-testing and gathering personal medical data. Early detection of symptoms can help improve the odds of fighting diseases in many cases, and this is especially true for cancer and diabetes. As such, frequent self-testing of sweat, urine, and blood can provide valuable medical insight into individuals and, more importantly, identify changes in health. 

If combined with AI diagnostic systems, it is even possible for health care to become entirely democratised, with the only purchases needing to be made are for low-cost test equipment, their consumables, and subscriptions to medical AI. Such an AI would unlikely offer subscription levels for diagnostic capabilities as this would arguably violate medical ethics and instead offer a single flat fee for everyone. 

Overall, the development of personal portable sensors will help accelerate developments in the medical field and, hopefully, provide low-cost medical services to everyone that are reliable, always available, and do not suffer from the many challenges faced by medical services around the world.