A phenomenon called ‚oxidative stress‘ is seen in affected organs during the early stages of certain difficult-to-treat diseases like cancer and kidney dysfunction. Detecting oxidative stress could thus enable early diagnosis and preventive treatments. But, the in vivo measurement of oxidative stress caused by both oxidation and reduction has historically been difficult. Now, scientists have developed an advanced quantum sensor technology that can detect ‚oxidative stress‘ non-invasively throughout the body using fluorescent imaging and MRI.