Scientists in northeast China say they have developed a “rapid and ultrasensitive” wearable dopamine sensor to monitor levels of the critical neurotransmitter. The smart patch could potentially be used for at-home tracking of conditions such as Parkinson’s disease and depression, according to the research team from the Chinese Academy of Sciences’ Shenyang Institute of Automation. They said the patch – which uses microscopic needles to test fluid just beneath the skin – was painless and...