Produced by researchers at the Chinese Academy of Sciences, it detects movements by patients (which can affect MRI results) in real time, thus reducing errors and the length of examinations
Having an MRI scan could be a much more comfortable experience in the future, as patients might be able to make small movements without having to redo the scan or spend a lot longer in the scanner. At present, patients have to stay completely still for minutes at a time because any shift from the optimum position affects the images, causing what are known as “motion artefacts”. However, staying completely still is far from simple and people can end up moving. It’s up to the MRI technician to notice any involuntary (or voluntary) movements by patients and interrupt examinations, when necessary, then resume when they are back in the right position. This approach relies on direct observation, so it can obviously lead to errors, delays and inaccuracies in the end results.
To resolve this issue, a group of engineers from the Chinese Academy of Sciences in Beijing have created a special sensor that goes under the part of the body being examined and sends a signal if the patient moves, automatically interrupting the scan, then starting it again when the patient is back in the right position and lying still once again. It might seem like a simple idea, but it’s tricky to put into practice with traditional sensors, because devices of this kind tend to interfere with the magnetic fields generated by the “machine” and affect the results. Consequently, they are not used.
So what have the Chinese researchers done? In the scientific journal ACS Sensors, they have explained that the new sensor uses a “triboelectric nanogenerator” (that’s the technical term for it) that can convert simple mechanical energy – such as movement or vibration – into electricity, with no need for magnetic materials. To put that in terms that are easier to grasp, in some cases, when two different materials touch each other and are then separated, there’s a transfer of electrons between the materials that creates an electric charge (for example, this is the process behind the “sparks” that are sometimes produced when you move around in synthetic clothing). Separating these charges induces a potential difference that can be used to generate an electric current.
The sensor developed by the Chinese researchers has a central layer of silicone between two layers of plastic film painted with graphite-based ink that can conduct weak electric currents. When pressure is put on the two plastic layers (for example, if a patient moves), their electrostatic charges move thanks to the conductive ink, creating a current that then flows out through a wire. The sensor can be fitted on a normal MRI table, and it does not create any interference.
During tests, when the patient turned their head or lifted it off the table, the sensor detected the movements, transmitted a signal to a computer and played an audible alert. The scan was interrupted automatically.
According to the researchers, a sensor of this kind could help to make MRI scans more efficient and less frustrating for both patients and technicians, while also producing better images.