“If I could read your mind.” Scientists seek better and better tools to help them understand what’s going on in a person’s brain under different conditions. The problem is that most brain scanning technologies require that the subject remain absolutely still. A motion of just tenths of an inch can render the images useless. Some systems detect the tiny magnetic fields generated by electrical currents in the brain, but these can weigh a thousand pounds or more, which means that they are hardly portable.

Researchers at the University of Nottingham have created a mobile brain scanner that lets the subject move freely. This means that instead of asking subjects to think about an apple, they can hold one in their hand. The system uses quantum sensors that are small enough to be mounted directly on the scalp, and that can operate at room temperature. Initially, the developers used a custom 3D-printed mask to hold the sensors, but future iterations will look more like a bike helmet. The sensors are so sensitive that they are disrupted by the Earth’s magnetic field as the subject moves. As a result, the researchers had to devise panels that provide a magnetic shield that reduces the normal fields by a factor of about 50,000.

This new design is more sensitive than traditional scanners, and will make it possible to measure children and patients who cannot keep still due to tremors. It will make it possible to read brain activity under more natural conditions than before. This technology should help scientists expand their understanding of brain functions while giving physicians a new tool for diagnosing neurological conditions.