If you’ve ever had a biometric screening to test your cholesterol, blood glucose, or other health metrics, you may be amazed that a tiny drop of blood can reveal so much information, so quickly. But collecting even a tiny pinprick of blood can be painful, especially for those with health conditions that require regular blood testing.
As a result, researchers are working hard to tap into an information-rich and readily available resource—sweat. From detecting dehydration to diagnosing cystic fibrosis to helping diabetics maintain a steady blood glucose level, sweat-sensing technologies are on the rise. Learn more about how flexible sweat sensors are poised to revolutionize the health technology industry.
What Sweat Can Reveal
Blood can be tested for hundreds of different hormones, enzymes, and other substances that may reveal chronic health issues. (For example, elevated levels of creatinine can be an early sign of kidney damage, while high levels of certain liver enzymes could mean it’s a good idea to cut down on one’s alcohol consumption).
But even the most sophisticated blood test only provides a picture of your health at that exact moment, and certain test results can be influenced by everything from how much sleep you got the night before to how much water you drank on the way to your appointment. As a result, blood tests may not always be the best way to monitor health conditions over the long term.
While sweat doesn’t contain all the same chemical components of blood (and therefore isn’t likely to replace blood testing any time soon), it does include electrolytes like sodium and potassium, amino acids, hormones, proteins, and other metabolites. These substances can be a treasure trove of information about dehydration, blood glucose levels, liver and kidney function, and other health metrics.
The Mechanics of Collecting and Analyzing Sweat
Currently, there are several different types of wearable sweat sensors being tested for commercial use. Researchers at UC Berkeley are working on a printing mechanism that transfers tiny spiral sensors to a thin sheet of wearable plastic, similar to a nicotine or birth control patch. These corkscrew-shaped sensors “wick up” sweat into the sensor, where it can immediately be analyzed and then transmitted via Bluetooth to a mobile device. Other startups are looking for ways to incorporate sweat sensors directly into wearable devices like wristwatches, sweatbands, and even workout wear.
But while the different paths to viable sweat-detecting technology are likely to lead to a variety of different inventions, one thing is for certain: sweat sensors must be able to reliably and consistently adjust for fluctuations in hydration levels, body temperature, diet, and a wide range of other variables. Because consumers are likely to use the information gleaned from sweat sensors to make changes to their daily habits, relying on incomplete or inaccurate data could have negative health consequences.
Development Challenges
Collecting and analyzing sweat in an accurate and replicable manner is not without some major challenges. In the past, researchers have experimented with collection receptacles ranging from absorbent pads to tiny tubes that attach to the skin. But these methods weren’t well-suited to the type of molecular analysis needed to get high-quality results. Newer technologies have shown promise when it comes to obtaining precise amounts of sweat from certain parts of the body.
And because each person’s sweat composition is as unique as a fingerprint, creating a technology that is literally “one size fits all” can sometimes seem like an insurmountable obstacle. Researchers are using exercise studies to collect sweat from participants under a variety of conditions to see whether the results they obtain can be replicated.
Finally, because the study of sweat (and, in particular, the connection between sweat data and blood data) is still relatively new, physicians and researchers are still trying to puzzle out how certain sweat measurements correlate to blood measurements and overall health. Cracking this code will be the most important step in making sweat-detecting devices available to the general public.
The Future of Sweat Technology 
Around 25 percent of all American adults regularly wear a fitness device that tracks their steps, heart rate, respiration, and even the quality of their sleep, using this data to make healthy and sustainable changes to their daily life.
With this sort of potential market share and the recent advances in sweat-detecting technology, it seems entirely possible that a sweat-detecting smartwatch or similar device will be available for purchase within the next few years. And as with all new health technology, a commitment to regulatory compliance will play a key role in bringing these devices to market—from ensuring that they securely maintain an individual’s private health data to preventing false positives or inaccurate results that could lead users down a diagnostic rabbit hole.