If you go to the hospital or your doctor’s office with a problem, you can generally expect to get weighed, measured, and have your temperature, pulse, and blood pressure taken. If you have a complaint with no readily apparent answer, you know what comes next: you “give” some blood. Then you wait. In a hospital with its own lab, test results can come back within an hour; otherwise, it usually takes a day or more for blood test results. What if biometric testing were quicker, noninvasive, and highly accurate? That’s the promise and the possibility that University of Cincinnati engineering professor Jason Heikenfeld and grad student Zachary Sonner are working on: a better biosensor to induce and monitor sweat.

One good thing about drawing blood: stick a needle in and you’ll get some. The patient can be awake, sleeping, or anywhere in between, but blood’s ready availability has been a major advantage over other biomaterials. Heikenfeld says sweat produces essentially the same useful data as blood. The researchers’ goal has been to create a way to make people sweat whenever and for long as needed to monitor biometrics. The new approach uses the chemical carbachol with 0.2 milliamps of electricity under a sensor held in place on the skin. The device is about the size of a band-aid. The first step for the UC scientists was to obtain useful readings from a subject’s sweat for up to 30 minutes. According to Heikenfeld, in later studies, varying concentrations of carbachol induced sufficient sweating for sensor measurement for several days.

Blood tests only provide single data points in time. Monitoring hormones or other chemicals biosensors continuously holds the promises of more accurate readings over time, the ability to observe cycles or shifts, and the potential to sound alerts when the results warrant. The UC researchers published their study in Lab on a Chip on July 25, 2017.