Release date: 2018-03-23
Brain Scanner. Credit: Wellcome/Nature
This article is reproduced from "澎湃新闻".
However, Dr. Matthew Brookes from the Sir Peter Mansfield Imaging Center at the University of Nottingham in the United Kingdom and others believe that MEG still has these shortcomings and has been working to improve the MEG system in recent years. In the early morning of March 22, Beijing time, the top academic journal Nature published the latest achievement of Brookes as a communication author: a prototype of a wearable brain scanner.
The magnetoencephalogram, which is the magnetic field generated by measuring the scalp nerve current, obtains the electrophysiological data of the human brain and can be directly imaged. The brain network can be reflected in real time through a three-dimensional image formed by mathematical analysis of the magnetic field.
However, the use of magnetoencephalography to measure brain activity is currently mainly by placing a large number of superconducting sensors around the brain. These cryogenically cooled sensors are sensitive to the fT level, allowing the detection of weak magnetic fields generated by the human brain.
As mentioned in the paper, unfortunately, the requirement of cooling means that the sensor must be packaged in a vacuum liquid nitrogen dewar and kept away from the scalp. Therefore, the MEG system is very cumbersome and the position of the sensor is also fixed in a universal helmet that cannot be moved. Once the position of the head relative to the sensor is slightly changed, the quality of the resulting data will drop significantly, even if it is 5 mm.
Traditional magnetoencephalography equipment
The traditional 275-channel magnetoencephalography device, which weighs about 900 pounds, is fixed and heavy, and the tester must remain stationary relative to the fixed sensor array.
In addition, in reality, not all the distance between the tester's head and the sensor is fixed, which also hinders the measurement. This distance for adults is usually 3 cm, but if the head of the person being tested is small, such as a baby, the distance will increase and the magnetic field will decrease accordingly, resulting in fewer available signals.
Therefore, Brookes et al. believe that these characteristics of the MEG system make the technology limited in many groups, including infants, and the environment requirements are extremely high.
How to make it suitable for all groups, regardless of the occasion, became the core direction for Brookes and his colleagues to develop new system prototypes.
3D print helmet
In the end, the research team developed a helmet called the OPM-MEG system. The helmet is printed in 3D and weighs only 905 grams, less than 2 pounds, and can be "privately customized" to ensure that the sensor (which only covers the right sensory cortex in the prototype) and the scalp of each tester The surface is in direct contact. After being put on the helmet, the testee is still free to carry out head activities.
The paper mentions that the core of the OPM-MEG system is the Optical Pump Magnetometers (OPMs), a magnetic field sensor that relies on the characteristics of alkali metal atoms with extremely high sensitivity up to ±0.01 nT. Each sensor has a glass colorimetric cell containing 87Rb (铷), which produces 87Rb of steam when heated to 150°C.
Although the internal temperature rises, the sensors can still be placed on the surface of the scalp because their external surface temperature is close to body temperature.
In the first demonstration, the team tested the electrophysiological activity of the tester's right sensory cortex. In the OPM-MEG experimental group, the tester had to perform 12 tests, 6 times as far as possible to remain still, and the other 6 times to do some natural head movements, including nodding, shaking his head, stretching his head and drinking water. One camera would be responsible for tracking the head. Departmental movement. The research team also tested a static set of controlled experiments using traditional MEG techniques.
In the OPM-MEG experimental group, the range of movement while keeping it as far as possible is ±1 cm, and when the head can move, the range is expanded to ±10 cm. The experiment finally showed that the wearable system can still collect high fidelity data even in the case of large head movements.
The researchers believe that the new system will enable infants, children and people with movement disorders to test their brain activity directly for the first time. Moreover, the tester can wear the helmet for social activities in the future without any influence.
Source: 澎湃News
Injectio,Nursing Andprotective Equipment
Henan Anbang Medical Supplies Co., Ltd. , https://www.anbangmedical.com