A Northwestern University research team has developed a first-of-its-kind soft, flexible microfluidic device that easily adheres to the skin and measures the wearer’s sweat to show how his or her body is responding to exercise.   A little larger than a quarter and about the same thickness, the simple, low-cost device analyzes key biomarkers to help a person decide quickly if any adjustments, such as drinking more water or replenishing electrolytes, need to be made or if something is medically ...