We’ve written about sweat sensors many times in the past. Researchers have good reasons to search for biometric data from sweat; the material is readily available and does not require invasive procedures to acquire. In addition to the familiar salts, sweat contains a variety of electrolytes and metabolites that can reveal valuable health information about an individual.

A group at UC Berkeley have taken this approach to a new level. They have created a wearable patch that includes sensors to detect various chemicals. One important feature of the patch is that it is printed on a flexible plastic substrate film using roll-to-roll processes, which means that it can be produced at scale at low cost.

The patch has a spiral microfluidic channel that wicks up the sweat. The speed of the sweat through the channel provides a measure of the rate of sweating. The channel takes the sweat to sensors that detect biomarkers such as potassium, sodium, and glucose.

One interesting result from their research is that sweat glucose measurements don’t correlate well with blood glucose levels. This is a disappointment as sweat would be a convenient way for diabetics to monitor blood sugar levels, but it’s not that simple. The researchers point out that there may yet be a combination of parameters that might be a more reliable way to infer blood glucose levels, but glucose in sweat is not sufficient on its own.